Add latest changes from gitlab-org/gitlab@master

29 files changed, 2627 insertions, 31 deletions

diff --git a/spec/controllers/projects/issues_controller_spec.rb b/spec/controllers/projects/issues_controller_spec.rb
index 35b43afbcf3..a2df023fe4c 100644
--- a/spec/controllers/projects/issues_controller_spec.rb
+++ b/spec/controllers/projects/issues_controller_spec.rb
@@ -243,6 +243,91 @@ describe Projects::IssuesController do
     end
   end
 
+  describe '#related_branches' do
+    subject { get :related_branches, params: params, format: :json }
+
+    before do
+      sign_in(user)
+      project.add_developer(developer)
+    end
+
+    let(:developer) { user }
+    let(:params) do
+      {
+        namespace_id: project.namespace,
+        project_id: project,
+        id: issue.iid
+      }
+    end
+
+    context 'the current user cannot download code' do
+      it 'prevents access' do
+        allow(controller).to receive(:can?).with(any_args).and_return(true)
+        allow(controller).to receive(:can?).with(user, :download_code, project).and_return(false)
+
+        subject
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
+    context 'there are no related branches' do
+      it 'assigns empty arrays', :aggregate_failures do
+        subject
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(assigns(:related_branches)).to be_empty
+        expect(response).to render_template('projects/issues/_related_branches')
+        expect(json_response).to eq('html' => '')
+      end
+    end
+
+    context 'there are related branches' do
+      let(:missing_branch) { "#{issue.to_branch_name}-missing" }
+      let(:unreadable_branch) { "#{issue.to_branch_name}-unreadable" }
+      let(:pipeline) { build(:ci_pipeline, :success, project: project) }
+      let(:master_branch) { 'master' }
+
+      let(:related_branches) do
+        [
+          branch_info(issue.to_branch_name, pipeline.detailed_status(user)),
+          branch_info(missing_branch, nil),
+          branch_info(unreadable_branch, nil)
+        ]
+      end
+
+      def branch_info(name, status)
+        {
+          name: name,
+          link: controller.project_compare_path(project, from: master_branch, to: name),
+          pipeline_status: status
+        }
+      end
+
+      before do
+        allow(controller).to receive(:find_routable!)
+          .with(Project, project.full_path, any_args).and_return(project)
+        allow(project).to receive(:default_branch).and_return(master_branch)
+        allow_next_instance_of(Issues::RelatedBranchesService) do |service|
+          allow(service).to receive(:execute).and_return(related_branches)
+        end
+      end
+
+      it 'finds and assigns the appropriate branch information', :aggregate_failures do
+        subject
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(assigns(:related_branches)).to contain_exactly(
+          branch_info(issue.to_branch_name, an_instance_of(Gitlab::Ci::Status::Success)),
+          branch_info(missing_branch, be_nil),
+          branch_info(unreadable_branch, be_nil)
+        )
+        expect(response).to render_template('projects/issues/_related_branches')
+        expect(json_response).to match('html' => String)
+      end
+    end
+  end
+
   # This spec runs as a request-style spec in order to invoke the
   # Rails router. A controller-style spec matches the wrong route, and
   # session['user_return_to'] becomes incorrect.
diff --git a/spec/factories/design_management/actions.rb b/spec/factories/design_management/actions.rb
new file mode 100644
index 00000000000..e2561f98f52
--- /dev/null
+++ b/spec/factories/design_management/actions.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :design_action, class: 'DesignManagement::Action' do
+    design
+    association :version, factory: :design_version
+    event { :creation }
+
+    trait :with_image_v432x230 do
+      image_v432x230 { fixture_file_upload('spec/fixtures/dk.png') }
+    end
+  end
+end
diff --git a/spec/factories/design_management/design_at_version.rb b/spec/factories/design_management/design_at_version.rb
new file mode 100644
index 00000000000..b73df71595c
--- /dev/null
+++ b/spec/factories/design_management/design_at_version.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :design_at_version, class: 'DesignManagement::DesignAtVersion' do
+    skip_create # This is not an Active::Record model.
+
+    design { nil }
+
+    version { nil }
+
+    transient do
+      issue { design&.issue || version&.issue || create(:issue) }
+    end
+
+    initialize_with do
+      attrs = attributes.dup
+      attrs[:design] ||= create(:design, issue: issue)
+      attrs[:version] ||= create(:design_version, issue: issue)
+
+      new(attrs)
+    end
+  end
+end
diff --git a/spec/factories/design_management/designs.rb b/spec/factories/design_management/designs.rb
new file mode 100644
index 00000000000..59d4cc56f95
--- /dev/null
+++ b/spec/factories/design_management/designs.rb
@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :design, class: 'DesignManagement::Design' do
+    issue { create(:issue) }
+    project { issue&.project || create(:project) }
+    sequence(:filename) { |n| "homescreen-#{n}.jpg" }
+
+    transient do
+      author { issue.author }
+    end
+
+    trait :importing do
+      issue { nil }
+
+      importing { true }
+      imported { false }
+    end
+
+    trait :imported do
+      importing { false }
+      imported { true }
+    end
+
+    create_versions = ->(design, evaluator, commit_version) do
+      unless evaluator.versions_count.zero?
+        project = design.project
+        issue = design.issue
+        repository = project.design_repository
+        repository.create_if_not_exists
+        dv_table_name = DesignManagement::Action.table_name
+        updates = [0, evaluator.versions_count - (evaluator.deleted ? 2 : 1)].max
+
+        run_action = ->(action) do
+          sha = commit_version[action]
+          version = DesignManagement::Version.new(sha: sha, issue: issue, author: evaluator.author)
+          version.save(validate: false) # We need it to have an ID, validate later
+          Gitlab::Database.bulk_insert(dv_table_name, [action.row_attrs(version)])
+        end
+
+        # always a creation
+        run_action[DesignManagement::DesignAction.new(design, :create, evaluator.file)]
+
+        # 0 or more updates
+        updates.times do
+          run_action[DesignManagement::DesignAction.new(design, :update, evaluator.file)]
+        end
+
+        # and maybe a deletion
+        run_action[DesignManagement::DesignAction.new(design, :delete)] if evaluator.deleted
+      end
+
+      design.clear_version_cache
+    end
+
+    # Use this trait to build designs that are backed by Git LFS, committed
+    # to the repository, and with an LfsObject correctly created for it.
+    trait :with_lfs_file do
+      with_file
+
+      transient do
+        raw_file { fixture_file_upload('spec/fixtures/dk.png', 'image/png') }
+        lfs_pointer { Gitlab::Git::LfsPointerFile.new(SecureRandom.random_bytes) }
+        file { lfs_pointer.pointer }
+      end
+
+      after :create do |design, evaluator|
+        lfs_object = create(:lfs_object, file: evaluator.raw_file, oid: evaluator.lfs_pointer.sha256, size: evaluator.lfs_pointer.size)
+        create(:lfs_objects_project, project: design.project, lfs_object: lfs_object, repository_type: :design)
+      end
+    end
+
+    # Use this trait if you want versions in a particular history, but don't
+    # want to pay for gitlay calls.
+    trait :with_versions do
+      transient do
+        deleted { false }
+        versions_count { 1 }
+        sequence(:file) { |n| "some-file-content-#{n}" }
+      end
+
+      after :create do |design, evaluator|
+        counter = (1..).lazy
+
+        # Just produce a SHA by hashing the action and a monotonic counter
+        commit_version = ->(action) do
+          Digest::SHA1.hexdigest("#{action.gitaly_action}.#{counter.next}")
+        end
+
+        create_versions[design, evaluator, commit_version]
+      end
+    end
+
+    # Use this trait to build designs that have commits in the repository
+    # and files that can be retrieved.
+    trait :with_file do
+      transient do
+        deleted { false }
+        versions_count { 1 }
+        file { File.join(Rails.root, 'spec/fixtures/dk.png') }
+      end
+
+      after :create do |design, evaluator|
+        project = design.project
+        repository = project.design_repository
+
+        commit_version = ->(action) do
+          repository.multi_action(
+            evaluator.author,
+            branch_name: 'master',
+            message: "#{action.action} for #{design.filename}",
+            actions: [action.gitaly_action]
+          )
+        end
+
+        create_versions[design, evaluator, commit_version]
+      end
+    end
+
+    trait :with_smaller_image_versions do
+      with_lfs_file
+
+      after :create do |design|
+        design.versions.each { |v| DesignManagement::GenerateImageVersionsService.new(v).execute }
+      end
+    end
+  end
+end
diff --git a/spec/factories/design_management/versions.rb b/spec/factories/design_management/versions.rb
new file mode 100644
index 00000000000..878665e02e5
--- /dev/null
+++ b/spec/factories/design_management/versions.rb
@@ -0,0 +1,142 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :design_version, class: 'DesignManagement::Version' do
+    sequence(:sha) { |n| Digest::SHA1.hexdigest("commit-like-#{n}") }
+    issue { designs.first&.issue || create(:issue) }
+    author { issue&.author || create(:user) }
+
+    transient do
+      designs_count { 1 }
+      created_designs { [] }
+      modified_designs { [] }
+      deleted_designs { [] }
+    end
+
+    # Warning: this will intentionally result in an invalid version!
+    trait :empty do
+      designs_count { 0 }
+    end
+
+    trait :importing do
+      issue { nil }
+
+      designs_count { 0 }
+      importing { true }
+      imported { false }
+    end
+
+    trait :imported do
+      importing { false }
+      imported { true }
+    end
+
+    after(:build) do |version, evaluator|
+      # By default all designs are created_designs, so just add them.
+      specific_designs = [].concat(
+        evaluator.created_designs,
+        evaluator.modified_designs,
+        evaluator.deleted_designs
+      )
+      version.designs += specific_designs
+
+      unless evaluator.designs_count.zero? || version.designs.present?
+        version.designs << create(:design, issue: version.issue)
+      end
+    end
+
+    after :create do |version, evaluator|
+      # FactoryBot does not like methods, so we use lambdas instead
+      events = DesignManagement::Action.events
+
+      version.actions
+        .where(design_id: evaluator.modified_designs.map(&:id))
+        .update_all(event: events[:modification])
+
+      version.actions
+        .where(design_id: evaluator.deleted_designs.map(&:id))
+        .update_all(event: events[:deletion])
+
+      version.designs.reload
+      # Ensure version.issue == design.issue for all version.designs
+      version.designs.update_all(issue_id: version.issue_id)
+
+      needed = evaluator.designs_count
+      have = version.designs.size
+
+      create_list(:design, [0, needed - have].max, issue: version.issue).each do |d|
+        version.designs << d
+      end
+
+      version.actions.reset
+    end
+
+    # Use this trait to build versions with designs that are backed by Git LFS, committed
+    # to the repository, and with an LfsObject correctly created for it.
+    trait :with_lfs_file do
+      committed
+
+      transient do
+        raw_file { fixture_file_upload('spec/fixtures/dk.png', 'image/png') }
+        lfs_pointer { Gitlab::Git::LfsPointerFile.new(SecureRandom.random_bytes) }
+        file { lfs_pointer.pointer }
+      end
+
+      after :create do |version, evaluator|
+        lfs_object = create(:lfs_object, file: evaluator.raw_file, oid: evaluator.lfs_pointer.sha256, size: evaluator.lfs_pointer.size)
+        create(:lfs_objects_project, project: version.project, lfs_object: lfs_object, repository_type: :design)
+      end
+    end
+
+    # This trait is for versions that must be present in the git repository.
+    trait :committed do
+      transient do
+        file { File.join(Rails.root, 'spec/fixtures/dk.png') }
+      end
+
+      after :create do |version, evaluator|
+        project = version.issue.project
+        repository = project.design_repository
+        repository.create_if_not_exists
+
+        designs = version.designs_by_event
+        base_change = { content: evaluator.file }
+
+        actions = %w[modification deletion].flat_map { |k| designs.fetch(k, []) }.map do |design|
+          base_change.merge(action: :create, file_path: design.full_path)
+        end
+
+        if actions.present?
+          repository.multi_action(
+            evaluator.author,
+            branch_name: 'master',
+            message: "created #{actions.size} files",
+            actions: actions
+          )
+        end
+
+        mapping = {
+          'creation' => :create,
+          'modification' => :update,
+          'deletion' => :delete
+        }
+
+        version_actions = designs.flat_map do |(event, designs)|
+          base = event == 'deletion' ? {} : base_change
+          designs.map do |design|
+            base.merge(action: mapping[event], file_path: design.full_path)
+          end
+        end
+
+        sha = repository.multi_action(
+          evaluator.author,
+          branch_name: 'master',
+          message: "edited #{version_actions.size} files",
+          actions: version_actions
+        )
+
+        version.update(sha: sha)
+      end
+    end
+  end
+end
diff --git a/spec/factories/notes.rb b/spec/factories/notes.rb
index fdd1a9a18b2..0868e38f70e 100644
--- a/spec/factories/notes.rb
+++ b/spec/factories/notes.rb
@@ -107,6 +107,10 @@ FactoryBot.define do
       end
     end
 
+    factory :diff_note_on_design, parent: :note, traits: [:on_design], class: 'DiffNote' do
+      position { build(:image_diff_position, file: noteable.full_path, diff_refs: noteable.diff_refs) }
+    end
+
     trait :on_commit do
       association :project, :repository
       noteable { nil }
@@ -136,6 +140,20 @@ FactoryBot.define do
       project { nil }
     end
 
+    trait :on_design do
+      transient do
+        issue { association(:issue, project: project) }
+      end
+      noteable { association(:design, :with_file, issue: issue) }
+
+      after(:build) do |note|
+        next if note.project == note.noteable.project
+
+        # note validations require consistency between these two objects
+        note.project = note.noteable.project
+      end
+    end
+
     trait :system do
       system { true }
     end
diff --git a/spec/factories/projects.rb b/spec/factories/projects.rb
index 64321c9f319..45caa7a2b6a 100644
--- a/spec/factories/projects.rb
+++ b/spec/factories/projects.rb
@@ -215,6 +215,12 @@ FactoryBot.define do
       end
     end
 
+    trait :design_repo do
+      after(:create) do |project|
+        raise 'Failed to create design repository!' unless project.design_repository.create_if_not_exists
+      end
+    end
+
     trait :remote_mirror do
       transient do
         remote_name { "remote_mirror_#{SecureRandom.hex}" }
diff --git a/spec/factories/uploads.rb b/spec/factories/uploads.rb
index a060cd7d6f8..b19af277cc3 100644
--- a/spec/factories/uploads.rb
+++ b/spec/factories/uploads.rb
@@ -65,5 +65,11 @@ FactoryBot.define do
       model { create(:note) }
       uploader { "AttachmentUploader" }
     end
+
+    trait :design_action_image_v432x230_upload do
+      mount_point { :image_v432x230 }
+      model { create(:design_action) }
+      uploader { ::DesignManagement::DesignV432x230Uploader.name }
+    end
   end
 end
diff --git a/spec/frontend/alert_management/components/alert_management_list_spec.js b/spec/frontend/alert_management/components/alert_management_list_spec.js
index a47363f4dc7..e45a9042f71 100644
--- a/spec/frontend/alert_management/components/alert_management_list_spec.js
+++ b/spec/frontend/alert_management/components/alert_management_list_spec.js
@@ -1,5 +1,5 @@
 import { mount } from '@vue/test-utils';
-import { GlEmptyState, GlTable, GlAlert, GlLoadingIcon } from '@gitlab/ui';
+import { GlEmptyState, GlTable, GlAlert, GlLoadingIcon, GlNewDropdown } from '@gitlab/ui';
 import AlertManagementList from '~/alert_management/components/alert_management_list.vue';
 
 import mockAlerts from '../mocks/alerts.json';
@@ -11,6 +11,7 @@ describe('AlertManagementList', () => {
   const findAlerts = () => wrapper.findAll('table tbody tr');
   const findAlert = () => wrapper.find(GlAlert);
   const findLoader = () => wrapper.find(GlLoadingIcon);
+  const findStatusDropdown = () => wrapper.find(GlNewDropdown);
 
   function mountComponent({
     props = {
@@ -103,5 +104,14 @@ describe('AlertManagementList', () => {
       expect(findAlertsTable().exists()).toBe(true);
       expect(findAlerts()).toHaveLength(mockAlerts.length);
     });
+
+    it('displays status dropdown', () => {
+      mountComponent({
+        props: { alertManagementEnabled: true, userCanEnableAlertManagement: true },
+        data: { alerts: mockAlerts, errored: false },
+        loading: false,
+      });
+      expect(findStatusDropdown().exists()).toBe(true);
+    });
   });
 });
diff --git a/spec/lib/gitlab/git_access_design_spec.rb b/spec/lib/gitlab/git_access_design_spec.rb
new file mode 100644
index 00000000000..b09afc67c90
--- /dev/null
+++ b/spec/lib/gitlab/git_access_design_spec.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+describe Gitlab::GitAccessDesign do
+  include DesignManagementTestHelpers
+
+  let_it_be(:project) { create(:project) }
+  let_it_be(:user) { project.owner }
+  let(:protocol) { 'web' }
+  let(:actor) { user }
+
+  subject(:access) do
+    described_class.new(actor, project, protocol, authentication_abilities: [:read_project, :download_code, :push_code])
+  end
+
+  describe '#check' do
+    subject { access.check('git-receive-pack', ::Gitlab::GitAccess::ANY) }
+
+    before do
+      enable_design_management
+    end
+
+    context 'when the user is allowed to manage designs' do
+      # TODO This test is being temporarily skipped unless run in EE,
+      # as we are in the process of moving Design Management to FOSS in 13.0
+      # in steps. In the current step the policies have not yet been moved
+      # which means that although the `GitAccessDesign` class has moved, the
+      # user will always be denied access in FOSS.
+      #
+      # See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283.
+      it do
+        skip 'See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283' unless Gitlab.ee?
+
+        is_expected.to be_a(::Gitlab::GitAccessResult::Success)
+      end
+    end
+
+    context 'when the user is not allowed to manage designs' do
+      let_it_be(:user) { create(:user) }
+
+      it 'raises an error' do
+        expect { subject }.to raise_error(::Gitlab::GitAccess::ForbiddenError)
+      end
+    end
+
+    context 'when the protocol is not web' do
+      let(:protocol) { 'https' }
+
+      it 'raises an error' do
+        expect { subject }.to raise_error(::Gitlab::GitAccess::ForbiddenError)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/gl_repository/repo_type_spec.rb b/spec/lib/gitlab/gl_repository/repo_type_spec.rb
index 6185b068d4c..bf6df55b71e 100644
--- a/spec/lib/gitlab/gl_repository/repo_type_spec.rb
+++ b/spec/lib/gitlab/gl_repository/repo_type_spec.rb
@@ -7,6 +7,7 @@ describe Gitlab::GlRepository::RepoType do
   let_it_be(:project_snippet) { create(:project_snippet, project: project, author: project.owner) }
   let(:project_path) { project.repository.full_path }
   let(:wiki_path) { project.wiki.repository.full_path }
+  let(:design_path) { project.design_repository.full_path }
   let(:personal_snippet_path) { "snippets/#{personal_snippet.id}" }
   let(:project_snippet_path) { "#{project.full_path}/snippets/#{project_snippet.id}" }
 
@@ -24,6 +25,7 @@ describe Gitlab::GlRepository::RepoType do
         expect(described_class).not_to be_wiki
         expect(described_class).to be_project
         expect(described_class).not_to be_snippet
+        expect(described_class).not_to be_design
       end
     end
 
@@ -33,6 +35,7 @@ describe Gitlab::GlRepository::RepoType do
         expect(described_class.valid?(wiki_path)).to be_truthy
         expect(described_class.valid?(personal_snippet_path)).to be_truthy
         expect(described_class.valid?(project_snippet_path)).to be_truthy
+        expect(described_class.valid?(design_path)).to be_truthy
       end
     end
   end
@@ -51,6 +54,7 @@ describe Gitlab::GlRepository::RepoType do
         expect(described_class).to be_wiki
         expect(described_class).not_to be_project
         expect(described_class).not_to be_snippet
+        expect(described_class).not_to be_design
       end
     end
 
@@ -60,6 +64,7 @@ describe Gitlab::GlRepository::RepoType do
         expect(described_class.valid?(wiki_path)).to be_truthy
         expect(described_class.valid?(personal_snippet_path)).to be_falsey
         expect(described_class.valid?(project_snippet_path)).to be_falsey
+        expect(described_class.valid?(design_path)).to be_falsey
       end
     end
   end
@@ -79,6 +84,7 @@ describe Gitlab::GlRepository::RepoType do
           expect(described_class).to be_snippet
           expect(described_class).not_to be_wiki
           expect(described_class).not_to be_project
+          expect(described_class).not_to be_design
         end
       end
 
@@ -88,6 +94,7 @@ describe Gitlab::GlRepository::RepoType do
           expect(described_class.valid?(wiki_path)).to be_falsey
           expect(described_class.valid?(personal_snippet_path)).to be_truthy
           expect(described_class.valid?(project_snippet_path)).to be_truthy
+          expect(described_class.valid?(design_path)).to be_falsey
         end
       end
     end
@@ -115,8 +122,38 @@ describe Gitlab::GlRepository::RepoType do
           expect(described_class.valid?(wiki_path)).to be_falsey
           expect(described_class.valid?(personal_snippet_path)).to be_truthy
           expect(described_class.valid?(project_snippet_path)).to be_truthy
+          expect(described_class.valid?(design_path)).to be_falsey
         end
       end
     end
   end
+
+  describe Gitlab::GlRepository::DESIGN do
+    it_behaves_like 'a repo type' do
+      let(:expected_identifier) { "design-#{project.id}" }
+      let(:expected_id) { project.id.to_s }
+      let(:expected_suffix) { '.design' }
+      let(:expected_repository) { project.design_repository }
+      let(:expected_container) { project }
+    end
+
+    it 'knows its type' do
+      aggregate_failures do
+        expect(described_class).to be_design
+        expect(described_class).not_to be_project
+        expect(described_class).not_to be_wiki
+        expect(described_class).not_to be_snippet
+      end
+    end
+
+    it 'checks if repository path is valid' do
+      aggregate_failures do
+        expect(described_class.valid?(design_path)).to be_truthy
+        expect(described_class.valid?(project_path)).to be_falsey
+        expect(described_class.valid?(wiki_path)).to be_falsey
+        expect(described_class.valid?(personal_snippet_path)).to be_falsey
+        expect(described_class.valid?(project_snippet_path)).to be_falsey
+      end
+    end
+  end
 end
diff --git a/spec/lib/gitlab/gl_repository_spec.rb b/spec/lib/gitlab/gl_repository_spec.rb
index 858f436047e..5f5244b7116 100644
--- a/spec/lib/gitlab/gl_repository_spec.rb
+++ b/spec/lib/gitlab/gl_repository_spec.rb
@@ -19,6 +19,10 @@ describe ::Gitlab::GlRepository do
       expect(described_class.parse("snippet-#{snippet.id}")).to eq([snippet, nil, Gitlab::GlRepository::SNIPPET])
     end
 
+    it 'parses a design gl_repository' do
+      expect(described_class.parse("design-#{project.id}")).to eq([project, project, Gitlab::GlRepository::DESIGN])
+    end
+
     it 'throws an argument error on an invalid gl_repository type' do
       expect { described_class.parse("badformat-#{project.id}") }.to raise_error(ArgumentError)
     end
@@ -27,4 +31,15 @@ describe ::Gitlab::GlRepository do
       expect { described_class.parse("project-foo") }.to raise_error(ArgumentError)
     end
   end
+
+  describe 'DESIGN' do
+    it 'uses the design access checker' do
+      expect(described_class::DESIGN.access_checker_class).to eq(::Gitlab::GitAccessDesign)
+    end
+
+    it 'builds a design repository' do
+      expect(described_class::DESIGN.repository_resolver.call(create(:project)))
+        .to be_a(::DesignManagement::Repository)
+    end
+  end
 end
diff --git a/spec/models/design_management/action_spec.rb b/spec/models/design_management/action_spec.rb
new file mode 100644
index 00000000000..753c31b1549
--- /dev/null
+++ b/spec/models/design_management/action_spec.rb
@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+describe DesignManagement::Action do
+  describe 'relations' do
+    it { is_expected.to belong_to(:design) }
+    it { is_expected.to belong_to(:version) }
+  end
+
+  describe 'scopes' do
+    describe '.most_recent' do
+      let_it_be(:design_a) { create(:design) }
+      let_it_be(:design_b) { create(:design) }
+      let_it_be(:design_c) { create(:design) }
+
+      let(:designs) { [design_a, design_b, design_c] }
+
+      before_all do
+        create(:design_version, designs: [design_a, design_b, design_c])
+        create(:design_version, designs: [design_a, design_b])
+        create(:design_version, designs: [design_a])
+      end
+
+      it 'finds the correct version for each design' do
+        dvs = described_class.where(design: designs)
+
+        expected = designs
+          .map(&:id)
+          .zip(dvs.order("version_id DESC").pluck(:version_id).uniq)
+
+        actual = dvs.most_recent.map { |dv| [dv.design_id, dv.version_id] }
+
+        expect(actual).to eq(expected)
+      end
+    end
+
+    describe '.up_to_version' do
+      let_it_be(:issue) { create(:issue) }
+      let_it_be(:design_a) { create(:design, issue: issue) }
+      let_it_be(:design_b) { create(:design, issue: issue) }
+
+      # let bindings are not available in before(:all) contexts,
+      # so we need to redefine the array on each construction.
+      let_it_be(:oldest) { create(:design_version, designs: [design_a, design_b]) }
+      let_it_be(:middle) { create(:design_version, designs: [design_a, design_b]) }
+      let_it_be(:newest) { create(:design_version, designs: [design_a, design_b]) }
+
+      subject { described_class.where(design: issue.designs).up_to_version(version) }
+
+      context 'the version is nil' do
+        let(:version) { nil }
+
+        it 'returns all design_versions' do
+          is_expected.to have_attributes(size: 6)
+        end
+      end
+
+      context 'when given a Version instance' do
+        context 'the version is the most current' do
+          let(:version) { newest }
+
+          it { is_expected.to have_attributes(size: 6) }
+        end
+
+        context 'the version is the oldest' do
+          let(:version) { oldest }
+
+          it { is_expected.to have_attributes(size: 2) }
+        end
+
+        context 'the version is the middle one' do
+          let(:version) { middle }
+
+          it { is_expected.to have_attributes(size: 4) }
+        end
+      end
+
+      context 'when given a commit SHA' do
+        context 'the version is the most current' do
+          let(:version) { newest.sha }
+
+          it { is_expected.to have_attributes(size: 6) }
+        end
+
+        context 'the version is the oldest' do
+          let(:version) { oldest.sha }
+
+          it { is_expected.to have_attributes(size: 2) }
+        end
+
+        context 'the version is the middle one' do
+          let(:version) { middle.sha }
+
+          it { is_expected.to have_attributes(size: 4) }
+        end
+      end
+
+      context 'when given a String that is not a commit SHA' do
+        let(:version) { 'foo' }
+
+        it { expect { subject }.to raise_error(ArgumentError) }
+      end
+    end
+  end
+end
diff --git a/spec/models/design_management/design_action_spec.rb b/spec/models/design_management/design_action_spec.rb
new file mode 100644
index 00000000000..da4ad41dfcb
--- /dev/null
+++ b/spec/models/design_management/design_action_spec.rb
@@ -0,0 +1,98 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+describe DesignManagement::DesignAction do
+  describe 'validations' do
+    describe 'the design' do
+      let(:fail_validation) { raise_error(/design/i) }
+
+      it 'must not be nil' do
+        expect { described_class.new(nil, :create, :foo) }.to fail_validation
+      end
+    end
+
+    describe 'the action' do
+      let(:fail_validation) { raise_error(/action/i) }
+
+      it 'must not be nil' do
+        expect { described_class.new(double, nil, :foo) }.to fail_validation
+      end
+
+      it 'must be a known action' do
+        expect { described_class.new(double, :wibble, :foo) }.to fail_validation
+      end
+    end
+
+    describe 'the content' do
+      context 'content is necesary' do
+        let(:fail_validation) { raise_error(/needs content/i) }
+
+        %i[create update].each do |action|
+          it "must not be nil if the action is #{action}" do
+            expect { described_class.new(double, action, nil) }.to fail_validation
+          end
+        end
+      end
+
+      context 'content is forbidden' do
+        let(:fail_validation) { raise_error(/forbids content/i) }
+
+        it "must not be nil if the action is delete" do
+          expect { described_class.new(double, :delete, :foo) }.to fail_validation
+        end
+      end
+    end
+  end
+
+  describe '#gitaly_action' do
+    let(:path) { 'some/path/somewhere' }
+    let(:design) { OpenStruct.new(full_path: path) }
+
+    subject { described_class.new(design, action, content) }
+
+    context 'the action needs content' do
+      let(:action) { :create }
+      let(:content) { :foo }
+
+      it 'produces a good gitaly action' do
+        expect(subject.gitaly_action).to eq(
+          action: action,
+          file_path: path,
+          content: content
+        )
+      end
+    end
+
+    context 'the action forbids content' do
+      let(:action) { :delete }
+      let(:content) { nil }
+
+      it 'produces a good gitaly action' do
+        expect(subject.gitaly_action).to eq(action: action, file_path: path)
+      end
+    end
+  end
+
+  describe '#issue_id' do
+    let(:issue_id) { :foo }
+    let(:design) { OpenStruct.new(issue_id: issue_id) }
+
+    subject { described_class.new(design, :delete) }
+
+    it 'delegates to the design' do
+      expect(subject.issue_id).to eq(issue_id)
+    end
+  end
+
+  describe '#performed' do
+    let(:design) { double }
+
+    subject { described_class.new(design, :delete) }
+
+    it 'calls design#clear_version_cache when the action has been performed' do
+      expect(design).to receive(:clear_version_cache)
+
+      subject.performed
+    end
+  end
+end
diff --git a/spec/models/design_management/design_at_version_spec.rb b/spec/models/design_management/design_at_version_spec.rb
new file mode 100644
index 00000000000..f6fa8df243c
--- /dev/null
+++ b/spec/models/design_management/design_at_version_spec.rb
@@ -0,0 +1,426 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DesignManagement::DesignAtVersion do
+  include DesignManagementTestHelpers
+
+  let_it_be(:issue, reload: true) { create(:issue) }
+  let_it_be(:issue_b, reload: true) { create(:issue) }
+  let_it_be(:design, reload: true) { create(:design, issue: issue) }
+  let_it_be(:version) { create(:design_version, designs: [design]) }
+
+  describe '#id' do
+    subject { described_class.new(design: design, version: version) }
+
+    it 'combines design.id and version.id' do
+      expect(subject.id).to include(design.id.to_s, version.id.to_s)
+    end
+  end
+
+  describe '#==' do
+    it 'identifies objects created with the same parameters as equal' do
+      design = build_stubbed(:design, issue: issue)
+      version = build_stubbed(:design_version, designs: [design], issue: issue)
+
+      this = build_stubbed(:design_at_version, design: design, version: version)
+      other = build_stubbed(:design_at_version, design: design, version: version)
+
+      expect(this).to eq(other)
+      expect(other).to eq(this)
+    end
+
+    it 'identifies unequal objects as unequal, by virtue of their version' do
+      design = build_stubbed(:design, issue: issue)
+      version_a = build_stubbed(:design_version, designs: [design])
+      version_b = build_stubbed(:design_version, designs: [design])
+
+      this = build_stubbed(:design_at_version, design: design, version: version_a)
+      other = build_stubbed(:design_at_version, design: design, version: version_b)
+
+      expect(this).not_to eq(nil)
+      expect(this).not_to eq(design)
+      expect(this).not_to eq(other)
+      expect(other).not_to eq(this)
+    end
+
+    it 'identifies unequal objects as unequal, by virtue of their design' do
+      design_a = build_stubbed(:design, issue: issue)
+      design_b = build_stubbed(:design, issue: issue)
+      version = build_stubbed(:design_version, designs: [design_a, design_b])
+
+      this = build_stubbed(:design_at_version, design: design_a, version: version)
+      other = build_stubbed(:design_at_version, design: design_b, version: version)
+
+      expect(this).not_to eq(other)
+      expect(other).not_to eq(this)
+    end
+
+    it 'rejects objects with the same id and the wrong class' do
+      dav = build_stubbed(:design_at_version)
+
+      expect(dav).not_to eq(OpenStruct.new(id: dav.id))
+    end
+
+    it 'expects objects to be of the same type, not subtypes' do
+      subtype = Class.new(described_class)
+      dav = build_stubbed(:design_at_version)
+      other = subtype.new(design: dav.design, version: dav.version)
+
+      expect(dav).not_to eq(other)
+    end
+  end
+
+  describe 'status methods' do
+    let!(:design_a) { create(:design, issue: issue) }
+    let!(:design_b) { create(:design, issue: issue) }
+
+    let!(:version_a) do
+      create(:design_version, designs: [design_a])
+    end
+    let!(:version_b) do
+      create(:design_version, designs: [design_b])
+    end
+    let!(:version_mod) do
+      create(:design_version, modified_designs: [design_a, design_b])
+    end
+    let!(:version_c) do
+      create(:design_version, deleted_designs: [design_a])
+    end
+    let!(:version_d) do
+      create(:design_version, deleted_designs: [design_b])
+    end
+    let!(:version_e) do
+      create(:design_version, designs: [design_a])
+    end
+
+    describe 'a design before it has been created' do
+      subject { build(:design_at_version, design: design_b, version: version_a) }
+
+      it 'is not deleted' do
+        expect(subject).not_to be_deleted
+      end
+
+      it 'has the status :not_created_yet' do
+        expect(subject).to have_attributes(status: :not_created_yet)
+      end
+    end
+
+    describe 'a design as of its creation' do
+      subject { build(:design_at_version, design: design_a, version: version_a) }
+
+      it 'is not deleted' do
+        expect(subject).not_to be_deleted
+      end
+
+      it 'has the status :current' do
+        expect(subject).to have_attributes(status: :current)
+      end
+    end
+
+    describe 'a design after it has been created, but before deletion' do
+      subject { build(:design_at_version, design: design_b, version: version_c) }
+
+      it 'is not deleted' do
+        expect(subject).not_to be_deleted
+      end
+
+      it 'has the status :current' do
+        expect(subject).to have_attributes(status: :current)
+      end
+    end
+
+    describe 'a design as of its modification' do
+      subject { build(:design_at_version, design: design_a, version: version_mod) }
+
+      it 'is not deleted' do
+        expect(subject).not_to be_deleted
+      end
+
+      it 'has the status :current' do
+        expect(subject).to have_attributes(status: :current)
+      end
+    end
+
+    describe 'a design as of its deletion' do
+      subject { build(:design_at_version, design: design_a, version: version_c) }
+
+      it 'is deleted' do
+        expect(subject).to be_deleted
+      end
+
+      it 'has the status :deleted' do
+        expect(subject).to have_attributes(status: :deleted)
+      end
+    end
+
+    describe 'a design after its deletion' do
+      subject { build(:design_at_version, design: design_b, version: version_e) }
+
+      it 'is deleted' do
+        expect(subject).to be_deleted
+      end
+
+      it 'has the status :deleted' do
+        expect(subject).to have_attributes(status: :deleted)
+      end
+    end
+
+    describe 'a design on its recreation' do
+      subject { build(:design_at_version, design: design_a, version: version_e) }
+
+      it 'is not deleted' do
+        expect(subject).not_to be_deleted
+      end
+
+      it 'has the status :current' do
+        expect(subject).to have_attributes(status: :current)
+      end
+    end
+  end
+
+  describe 'validations' do
+    subject(:design_at_version) { build(:design_at_version) }
+
+    it { is_expected.to be_valid }
+
+    describe 'a design-at-version without a design' do
+      subject { described_class.new(design: nil, version: build(:design_version)) }
+
+      it { is_expected.to be_invalid }
+
+      it 'mentions the design in the errors' do
+        subject.valid?
+
+        expect(subject.errors[:design]).to be_present
+      end
+    end
+
+    describe 'a design-at-version without a version' do
+      subject { described_class.new(design: build(:design), version: nil) }
+
+      it { is_expected.to be_invalid }
+
+      it 'mentions the version in the errors' do
+        subject.valid?
+
+        expect(subject.errors[:version]).to be_present
+      end
+    end
+
+    describe 'design_and_version_belong_to_the_same_issue' do
+      context 'both design and version are supplied' do
+        subject(:design_at_version) { build(:design_at_version, design: design, version: version) }
+
+        context 'the design belongs to the same issue as the version' do
+          it { is_expected.to be_valid }
+        end
+
+        context 'the design does not belong to the same issue as the version' do
+          let(:design) { create(:design) }
+          let(:version) { create(:design_version) }
+
+          it { is_expected.to be_invalid }
+        end
+      end
+
+      context 'the factory is just supplied with a design' do
+        let(:design) { create(:design) }
+
+        subject(:design_at_version) { build(:design_at_version, design: design) }
+
+        it { is_expected.to be_valid }
+      end
+
+      context 'the factory is just supplied with a version' do
+        let(:version) { create(:design_version) }
+
+        subject(:design_at_version) { build(:design_at_version, version: version) }
+
+        it { is_expected.to be_valid }
+      end
+    end
+
+    describe 'design_and_version_have_issue_id' do
+      subject(:design_at_version) { build(:design_at_version, design: design, version: version) }
+
+      context 'the design has no issue_id, because it is being imported' do
+        let(:design) { create(:design, :importing) }
+
+        it { is_expected.to be_invalid }
+      end
+
+      context 'the version has no issue_id, because it is being imported' do
+        let(:version) { create(:design_version, :importing) }
+
+        it { is_expected.to be_invalid }
+      end
+
+      context 'both the design and the version are being imported' do
+        let(:version) { create(:design_version, :importing) }
+        let(:design) { create(:design, :importing) }
+
+        it { is_expected.to be_invalid }
+      end
+    end
+  end
+
+  def id_of(design, version)
+    build(:design_at_version, design: design, version: version).id
+  end
+
+  describe '.instantiate' do
+    context 'when attrs are valid' do
+      subject do
+        described_class.instantiate(design: design, version: version)
+      end
+
+      it { is_expected.to be_a(described_class).and(be_valid) }
+    end
+
+    context 'when attrs are invalid' do
+      subject do
+        described_class.instantiate(
+          design: create(:design),
+          version: create(:design_version)
+        )
+      end
+
+      it 'raises a validation error' do
+        expect { subject }.to raise_error(ActiveModel::ValidationError)
+      end
+    end
+  end
+
+  describe '.lazy_find' do
+    let!(:version_a) do
+      create(:design_version, designs: create_list(:design, 3, issue: issue))
+    end
+    let!(:version_b) do
+      create(:design_version, designs: create_list(:design, 1, issue: issue))
+    end
+    let!(:version_c) do
+      create(:design_version, designs: create_list(:design, 1, issue: issue_b))
+    end
+
+    let(:id_a)   { id_of(version_a.designs.first,  version_a) }
+    let(:id_b)   { id_of(version_a.designs.second, version_a) }
+    let(:id_c)   { id_of(version_a.designs.last,   version_a) }
+    let(:id_d)   { id_of(version_b.designs.first,  version_b) }
+    let(:id_e)   { id_of(version_c.designs.first,  version_c) }
+    let(:bad_id) { id_of(version_c.designs.first,  version_a) }
+
+    def find(the_id)
+      described_class.lazy_find(the_id)
+    end
+
+    let(:db_calls) { 2 }
+
+    it 'issues fewer queries than the naive approach would' do
+      expect do
+        dav_a = find(id_a)
+        dav_b = find(id_b)
+        dav_c = find(id_c)
+        dav_d = find(id_d)
+        dav_e = find(id_e)
+        should_not_exist = find(bad_id)
+
+        expect(dav_a.version).to eq(version_a)
+        expect(dav_b.version).to eq(version_a)
+        expect(dav_c.version).to eq(version_a)
+        expect(dav_d.version).to eq(version_b)
+        expect(dav_e.version).to eq(version_c)
+        expect(should_not_exist).not_to be_present
+
+        expect(version_a.designs).to include(dav_a.design, dav_b.design, dav_c.design)
+        expect(version_b.designs).to include(dav_d.design)
+        expect(version_c.designs).to include(dav_e.design)
+      end.not_to exceed_query_limit(db_calls)
+    end
+  end
+
+  describe '.find' do
+    let(:results) { described_class.find(ids) }
+
+    # 2 versions, with 5 total designs on issue A, so 2*5 = 10
+    let!(:version_a) do
+      create(:design_version, designs: create_list(:design, 3, issue: issue))
+    end
+    let!(:version_b) do
+      create(:design_version, designs: create_list(:design, 2, issue: issue))
+    end
+    # 1 version, with 3 designs on issue B, so 1*3 = 3
+    let!(:version_c) do
+      create(:design_version, designs: create_list(:design, 3, issue: issue_b))
+    end
+
+    context 'invalid ids' do
+      let(:ids) do
+        version_b.designs.map { |d| id_of(d, version_c) }
+      end
+
+      describe '#count' do
+        it 'counts 0 records' do
+          expect(results.count).to eq(0)
+        end
+      end
+
+      describe '#empty?' do
+        it 'is empty' do
+          expect(results).to be_empty
+        end
+      end
+
+      describe '#to_a' do
+        it 'finds no records' do
+          expect(results.to_a).to eq([])
+        end
+      end
+    end
+
+    context 'valid ids' do
+      let(:red_herrings) { issue_b.designs.sample(2).map { |d| id_of(d, version_a) } }
+
+      let(:ids) do
+        a_ids = issue.designs.sample(2).map { |d| id_of(d, version_a) }
+        b_ids = issue.designs.sample(2).map { |d| id_of(d, version_b) }
+        c_ids = issue_b.designs.sample(2).map { |d| id_of(d, version_c) }
+
+        a_ids + b_ids + c_ids + red_herrings
+      end
+
+      before do
+        ids.size # force IDs
+      end
+
+      describe '#count' do
+        it 'counts 2 records' do
+          expect(results.count).to eq(6)
+        end
+
+        it 'issues at most two queries' do
+          expect { results.count }.not_to exceed_query_limit(2)
+        end
+      end
+
+      describe '#to_a' do
+        it 'finds 6 records' do
+          expect(results.size).to eq(6)
+          expect(results).to all(be_a(described_class))
+        end
+
+        it 'only returns records with matching IDs' do
+          expect(results.map(&:id)).to match_array(ids - red_herrings)
+        end
+
+        it 'only returns valid records' do
+          expect(results).to all(be_valid)
+        end
+
+        it 'issues at most two queries' do
+          expect { results.to_a }.not_to exceed_query_limit(2)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/models/design_management/design_collection_spec.rb b/spec/models/design_management/design_collection_spec.rb
new file mode 100644
index 00000000000..bd48f742042
--- /dev/null
+++ b/spec/models/design_management/design_collection_spec.rb
@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+describe DesignManagement::DesignCollection do
+  include DesignManagementTestHelpers
+
+  let_it_be(:issue, reload: true) { create(:issue) }
+
+  subject(:collection) { described_class.new(issue) }
+
+  describe ".find_or_create_design!" do
+    it "finds an existing design" do
+      design = create(:design, issue: issue, filename: 'world.png')
+
+      expect(collection.find_or_create_design!(filename: 'world.png')).to eq(design)
+    end
+
+    it "creates a new design if one didn't exist" do
+      expect(issue.designs.size).to eq(0)
+
+      new_design = collection.find_or_create_design!(filename: 'world.png')
+
+      expect(issue.designs.size).to eq(1)
+      expect(new_design.filename).to eq('world.png')
+      expect(new_design.issue).to eq(issue)
+    end
+
+    it "only queries the designs once" do
+      create(:design, issue: issue, filename: 'hello.png')
+      create(:design, issue: issue, filename: 'world.jpg')
+
+      expect do
+        collection.find_or_create_design!(filename: 'hello.png')
+        collection.find_or_create_design!(filename: 'world.jpg')
+      end.not_to exceed_query_limit(1)
+    end
+  end
+
+  describe "#versions" do
+    it "includes versions for all designs" do
+      version_1 = create(:design_version)
+      version_2 = create(:design_version)
+      other_version = create(:design_version)
+      create(:design, issue: issue, versions: [version_1])
+      create(:design, issue: issue, versions: [version_2])
+      create(:design, versions: [other_version])
+
+      expect(collection.versions).to contain_exactly(version_1, version_2)
+    end
+  end
+
+  describe "#repository" do
+    it "builds a design repository" do
+      expect(collection.repository).to be_a(DesignManagement::Repository)
+    end
+  end
+
+  describe '#designs_by_filename' do
+    let(:designs) { create_list(:design, 5, :with_file, issue: issue) }
+    let(:filenames) { designs.map(&:filename) }
+    let(:query) { subject.designs_by_filename(filenames) }
+
+    it 'finds all the designs with those filenames on this issue' do
+      expect(query).to have_attributes(size: 5)
+    end
+
+    it 'only makes a single query' do
+      designs.each(&:id)
+      expect { query }.not_to exceed_query_limit(1)
+    end
+
+    context 'some are deleted' do
+      before do
+        delete_designs(*designs.sample(2))
+      end
+
+      it 'takes deletion into account' do
+        expect(query).to have_attributes(size: 3)
+      end
+    end
+  end
+end
diff --git a/spec/models/design_management/design_spec.rb b/spec/models/design_management/design_spec.rb
new file mode 100644
index 00000000000..555b7f04f86
--- /dev/null
+++ b/spec/models/design_management/design_spec.rb
@@ -0,0 +1,582 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DesignManagement::Design do
+  include DesignManagementTestHelpers
+
+  let_it_be(:issue) { create(:issue) }
+  let_it_be(:design1) { create(:design, :with_versions, issue: issue, versions_count: 1) }
+  let_it_be(:design2) { create(:design, :with_versions, issue: issue, versions_count: 1) }
+  let_it_be(:design3) { create(:design, :with_versions, issue: issue, versions_count: 1) }
+  let_it_be(:deleted_design) { create(:design, :with_versions, deleted: true) }
+
+  describe 'relations' do
+    it { is_expected.to belong_to(:project) }
+    it { is_expected.to belong_to(:issue) }
+    it { is_expected.to have_many(:actions) }
+    it { is_expected.to have_many(:versions) }
+    it { is_expected.to have_many(:notes).dependent(:delete_all) }
+    it { is_expected.to have_many(:user_mentions) }
+  end
+
+  describe 'validations' do
+    subject(:design) { build(:design) }
+
+    it { is_expected.to be_valid }
+    it { is_expected.to validate_presence_of(:project) }
+    it { is_expected.to validate_presence_of(:issue) }
+    it { is_expected.to validate_presence_of(:filename) }
+    it { is_expected.to validate_uniqueness_of(:filename).scoped_to(:issue_id) }
+
+    it "validates that the extension is an image" do
+      design.filename = "thing.txt"
+      extensions = described_class::SAFE_IMAGE_EXT + described_class::DANGEROUS_IMAGE_EXT
+
+      expect(design).not_to be_valid
+      expect(design.errors[:filename].first).to eq(
+        "does not have a supported extension. Only #{extensions.to_sentence} are supported"
+      )
+    end
+
+    describe 'validating files with .svg extension' do
+      before do
+        design.filename = "thing.svg"
+      end
+
+      it "allows .svg files when feature flag is enabled" do
+        stub_feature_flags(design_management_allow_dangerous_images: true)
+
+        expect(design).to be_valid
+      end
+
+      it "does not allow .svg files when feature flag is disabled" do
+        stub_feature_flags(design_management_allow_dangerous_images: false)
+
+        expect(design).not_to be_valid
+        expect(design.errors[:filename].first).to eq(
+          "does not have a supported extension. Only #{described_class::SAFE_IMAGE_EXT.to_sentence} are supported"
+        )
+      end
+    end
+  end
+
+  describe 'scopes' do
+    describe '.visible_at_version' do
+      let(:versions) { DesignManagement::Version.where(issue: issue).ordered }
+      let(:found) { described_class.visible_at_version(version) }
+
+      context 'at oldest version' do
+        let(:version) { versions.last }
+
+        it 'finds the first design only' do
+          expect(found).to contain_exactly(design1)
+        end
+      end
+
+      context 'at version 2' do
+        let(:version) { versions.second }
+
+        it 'finds the first and second designs' do
+          expect(found).to contain_exactly(design1, design2)
+        end
+      end
+
+      context 'at latest version' do
+        let(:version) { versions.first }
+
+        it 'finds designs' do
+          expect(found).to contain_exactly(design1, design2, design3)
+        end
+      end
+
+      context 'when the argument is nil' do
+        let(:version) { nil }
+
+        it 'finds all undeleted designs' do
+          expect(found).to contain_exactly(design1, design2, design3)
+        end
+      end
+
+      describe 'one of the designs was deleted before the given version' do
+        before do
+          delete_designs(design2)
+        end
+
+        it 'is not returned' do
+          current_version = versions.first
+
+          expect(described_class.visible_at_version(current_version)).to contain_exactly(design1, design3)
+        end
+      end
+
+      context 'a re-created history' do
+        before do
+          delete_designs(design1, design2)
+          restore_designs(design1)
+        end
+
+        it 'is returned, though other deleted events are not' do
+          expect(described_class.visible_at_version(nil)).to contain_exactly(design1, design3)
+        end
+      end
+
+      # test that a design that has been modified at various points
+      # can be queried for correctly at different points in its history
+      describe 'dead or alive' do
+        let(:versions) { DesignManagement::Version.where(issue: issue).map { |v| [v, :alive] } }
+
+        before do
+          versions << [delete_designs(design1),          :dead]
+          versions << [modify_designs(design2),          :dead]
+          versions << [restore_designs(design1),         :alive]
+          versions << [modify_designs(design3),          :alive]
+          versions << [delete_designs(design1),          :dead]
+          versions << [modify_designs(design2, design3), :dead]
+          versions << [restore_designs(design1),         :alive]
+        end
+
+        it 'can establish the history at any point' do
+          history = versions.map(&:first).map do |v|
+            described_class.visible_at_version(v).include?(design1) ? :alive : :dead
+          end
+
+          expect(history).to eq(versions.map(&:second))
+        end
+      end
+    end
+
+    describe '.with_filename' do
+      it 'returns correct design when passed a single filename' do
+        expect(described_class.with_filename(design1.filename)).to eq([design1])
+      end
+
+      it 'returns correct designs when passed an Array of filenames' do
+        expect(
+          described_class.with_filename([design1, design2].map(&:filename))
+        ).to contain_exactly(design1, design2)
+      end
+    end
+
+    describe '.on_issue' do
+      it 'returns correct designs when passed a single issue' do
+        expect(described_class.on_issue(issue)).to match_array(issue.designs)
+      end
+
+      it 'returns correct designs when passed an Array of issues' do
+        expect(
+          described_class.on_issue([issue, deleted_design.issue])
+        ).to contain_exactly(design1, design2, design3, deleted_design)
+      end
+    end
+
+    describe '.current' do
+      it 'returns just the undeleted designs' do
+        delete_designs(design3)
+
+        expect(described_class.current).to contain_exactly(design1, design2)
+      end
+    end
+  end
+
+  describe '#visible_in?' do
+    let_it_be(:issue) { create(:issue) }
+
+    # It is expensive to re-create complex histories, so we do it once, and then
+    # assert that we can establish visibility at any given version.
+    it 'tells us when a design is visible' do
+      expected = []
+
+      first_design = create(:design, :with_versions, issue: issue, versions_count: 1)
+      prior_to_creation = first_design.versions.first
+      expected << [prior_to_creation, :not_created_yet, false]
+
+      v = modify_designs(first_design)
+      expected << [v, :not_created_yet, false]
+
+      design = create(:design, :with_versions, issue: issue, versions_count: 1)
+      created_in = design.versions.first
+      expected << [created_in, :created, true]
+
+      # The future state should not affect the result for any state, so we
+      # ensure that most states have a long future as well as a rich past
+      2.times do
+        v = modify_designs(first_design)
+        expected << [v, :unaffected_visible, true]
+
+        v = modify_designs(design)
+        expected << [v, :modified, true]
+
+        v = modify_designs(first_design)
+        expected << [v, :unaffected_visible, true]
+
+        v = delete_designs(design)
+        expected << [v, :deleted, false]
+
+        v = modify_designs(first_design)
+        expected << [v, :unaffected_nv, false]
+
+        v = restore_designs(design)
+        expected << [v, :restored, true]
+      end
+
+      delete_designs(design) # ensure visibility is not corelated with current state
+
+      got = expected.map do |(v, sym, _)|
+        [v, sym, design.visible_in?(v)]
+      end
+
+      expect(got).to eq(expected)
+    end
+  end
+
+  describe '#to_ability_name' do
+    it { expect(described_class.new.to_ability_name).to eq('design') }
+  end
+
+  describe '#status' do
+    context 'the design is new' do
+      subject { build(:design) }
+
+      it { is_expected.to have_attributes(status: :new) }
+    end
+
+    context 'the design is current' do
+      subject { design1 }
+
+      it { is_expected.to have_attributes(status: :current) }
+    end
+
+    context 'the design has been deleted' do
+      subject { deleted_design }
+
+      it { is_expected.to have_attributes(status: :deleted) }
+    end
+  end
+
+  describe '#deleted?' do
+    context 'the design is new' do
+      let(:design) { build(:design) }
+
+      it 'is falsy' do
+        expect(design).not_to be_deleted
+      end
+    end
+
+    context 'the design is current' do
+      let(:design) { design1 }
+
+      it 'is falsy' do
+        expect(design).not_to be_deleted
+      end
+    end
+
+    context 'the design has been deleted' do
+      let(:design) { deleted_design }
+
+      it 'is truthy' do
+        expect(design).to be_deleted
+      end
+    end
+
+    context 'the design has been deleted, but was then re-created' do
+      let(:design) { create(:design, :with_versions, versions_count: 1, deleted: true) }
+
+      it 'is falsy' do
+        restore_designs(design)
+
+        expect(design).not_to be_deleted
+      end
+    end
+  end
+
+  describe "#new_design?" do
+    let(:design) { design1 }
+
+    it "is false when there are versions" do
+      expect(design1).not_to be_new_design
+    end
+
+    it "is true when there are no versions" do
+      expect(build(:design)).to be_new_design
+    end
+
+    it 'is false for deleted designs' do
+      expect(deleted_design).not_to be_new_design
+    end
+
+    it "does not cause extra queries when actions are loaded" do
+      design.actions.map(&:id)
+
+      expect { design.new_design? }.not_to exceed_query_limit(0)
+    end
+
+    it "implicitly caches values" do
+      expect do
+        design.new_design?
+        design.new_design?
+      end.not_to exceed_query_limit(1)
+    end
+
+    it "queries again when the clear_version_cache trigger has been called" do
+      expect do
+        design.new_design?
+        design.clear_version_cache
+        design.new_design?
+      end.not_to exceed_query_limit(2)
+    end
+
+    it "causes a single query when there versions are not loaded" do
+      design.reload
+
+      expect { design.new_design? }.not_to exceed_query_limit(1)
+    end
+  end
+
+  describe "#full_path" do
+    it "builds the full path for a design" do
+      design = build(:design, filename: "hello.jpg")
+      expected_path = "#{DesignManagement.designs_directory}/issue-#{design.issue.iid}/hello.jpg"
+
+      expect(design.full_path).to eq(expected_path)
+    end
+  end
+
+  describe '#diff_refs' do
+    let(:design) { create(:design, :with_file, versions_count: versions_count) }
+
+    context 'there are several versions' do
+      let(:versions_count) { 3 }
+
+      it "builds diff refs based on the first commit and it's for the design" do
+        expect(design.diff_refs.base_sha).to eq(design.versions.ordered.second.sha)
+        expect(design.diff_refs.head_sha).to eq(design.versions.ordered.first.sha)
+      end
+    end
+
+    context 'there is just one version' do
+      let(:versions_count) { 1 }
+
+      it 'builds diff refs based on the empty tree if there was only one version' do
+        design = create(:design, :with_file, versions_count: 1)
+
+        expect(design.diff_refs.base_sha).to eq(Gitlab::Git::BLANK_SHA)
+        expect(design.diff_refs.head_sha).to eq(design.diff_refs.head_sha)
+      end
+    end
+
+    it 'has no diff ref if new' do
+      design = build(:design)
+
+      expect(design.diff_refs).to be_nil
+    end
+  end
+
+  describe '#repository' do
+    it 'is a design repository' do
+      design = build(:design)
+
+      expect(design.repository).to be_a(DesignManagement::Repository)
+    end
+  end
+
+  # TODO these tests are being temporarily skipped unless run in EE,
+  # as we are in the process of moving Design Management to FOSS in 13.0
+  # in steps. In the current step the routes have not yet been moved.
+  #
+  # See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283.
+  describe '#note_etag_key' do
+    it 'returns a correct etag key' do
+      skip 'See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283' unless Gitlab.ee?
+
+      design = create(:design)
+
+      expect(design.note_etag_key).to eq(
+        ::Gitlab::Routing.url_helpers.designs_project_issue_path(design.project, design.issue, { vueroute: design.filename })
+      )
+    end
+  end
+
+  describe '#user_notes_count', :use_clean_rails_memory_store_caching do
+    let_it_be(:design) { create(:design, :with_file) }
+
+    subject { design.user_notes_count }
+
+    # Note: Cache invalidation tests are in `design_user_notes_count_service_spec.rb`
+
+    it 'returns a count of user-generated notes' do
+      create(:diff_note_on_design, noteable: design)
+
+      is_expected.to eq(1)
+    end
+
+    it 'does not count notes on other designs' do
+      second_design = create(:design, :with_file)
+      create(:diff_note_on_design, noteable: second_design)
+
+      is_expected.to eq(0)
+    end
+
+    it 'does not count system notes' do
+      create(:diff_note_on_design, system: true, noteable: design)
+
+      is_expected.to eq(0)
+    end
+  end
+
+  describe '#after_note_changed' do
+    subject { build(:design) }
+
+    it 'calls #delete_cache on DesignUserNotesCountService' do
+      expect_next_instance_of(DesignManagement::DesignUserNotesCountService) do |service|
+        expect(service).to receive(:delete_cache)
+      end
+
+      subject.after_note_changed(build(:note))
+    end
+
+    it 'does not call #delete_cache on DesignUserNotesCountService when passed a system note' do
+      expect(DesignManagement::DesignUserNotesCountService).not_to receive(:new)
+
+      subject.after_note_changed(build(:note, :system))
+    end
+  end
+
+  describe '.for_reference' do
+    let_it_be(:design_a) { create(:design) }
+    let_it_be(:design_b) { create(:design) }
+
+    it 'avoids extra queries when calling to_reference' do
+      designs = described_class.for_reference.where(id: [design_a.id, design_b.id]).to_a
+
+      expect { designs.map(&:to_reference) }.not_to exceed_query_limit(0)
+    end
+  end
+
+  describe '#to_reference' do
+    let(:namespace) { build(:namespace, path: 'sample-namespace') }
+    let(:project)   { build(:project, name: 'sample-project', namespace: namespace) }
+    let(:group)     { create(:group, name: 'Group', path: 'sample-group') }
+    let(:issue)     { build(:issue, iid: 1, project: project) }
+    let(:filename)  { 'homescreen.jpg' }
+    let(:design)    { build(:design, filename: filename, issue: issue, project: project) }
+
+    context 'when nil argument' do
+      let(:reference) { design.to_reference }
+
+      it 'uses the simple format' do
+        expect(reference).to eq "#1[homescreen.jpg]"
+      end
+
+      context 'when the filename contains spaces, hyphens, periods, single-quotes, underscores and colons' do
+        let(:filename) { %q{a complex filename: containing - _ : etc., but still 'simple'.gif} }
+
+        it 'uses the simple format' do
+          expect(reference).to eq "#1[#{filename}]"
+        end
+      end
+
+      context 'when the filename contains HTML angle brackets' do
+        let(:filename) { 'a <em>great</em> filename.jpg' }
+
+        it 'uses Base64 encoding' do
+          expect(reference).to eq "#1[base64:#{Base64.strict_encode64(filename)}]"
+        end
+      end
+
+      context 'when the filename contains quotation marks' do
+        let(:filename) { %q{a "great" filename.jpg} }
+
+        it 'uses enclosing quotes, with backslash encoding' do
+          expect(reference).to eq %q{#1["a \"great\" filename.jpg"]}
+        end
+      end
+
+      context 'when the filename contains square brackets' do
+        let(:filename) { %q{a [great] filename.jpg} }
+
+        it 'uses enclosing quotes' do
+          expect(reference).to eq %q{#1["a [great] filename.jpg"]}
+        end
+      end
+    end
+
+    context 'when full is true' do
+      it 'returns complete path to the issue' do
+        refs = [
+          design.to_reference(full: true),
+          design.to_reference(project, full: true),
+          design.to_reference(group, full: true)
+        ]
+
+        expect(refs).to all(eq 'sample-namespace/sample-project#1/designs[homescreen.jpg]')
+      end
+    end
+
+    context 'when full is false' do
+      it 'returns complete path to the issue' do
+        refs = [
+          design.to_reference(build(:project), full: false),
+          design.to_reference(group, full: false)
+        ]
+
+        expect(refs).to all(eq 'sample-namespace/sample-project#1[homescreen.jpg]')
+      end
+    end
+
+    context 'when same project argument' do
+      it 'returns bare reference' do
+        expect(design.to_reference(project)).to eq("#1[homescreen.jpg]")
+      end
+    end
+  end
+
+  describe 'reference_pattern' do
+    let(:match) { described_class.reference_pattern.match(ref) }
+    let(:ref) { design.to_reference }
+    let(:design) { build(:design, filename: filename) }
+
+    context 'simple_file_name' do
+      let(:filename) { 'simple-file-name.jpg' }
+
+      it 'matches :simple_file_name' do
+        expect(match[:simple_file_name]).to eq(filename)
+      end
+    end
+
+    context 'quoted_file_name' do
+      let(:filename) { 'simple "file" name.jpg' }
+
+      it 'matches :simple_file_name' do
+        expect(match[:escaped_filename].gsub(/\\"/, '"')).to eq(filename)
+      end
+    end
+
+    context 'Base64 name' do
+      let(:filename) { '<>.png' }
+
+      it 'matches base_64_encoded_name' do
+        expect(Base64.decode64(match[:base_64_encoded_name])).to eq(filename)
+      end
+    end
+  end
+
+  describe '.by_issue_id_and_filename' do
+    let_it_be(:issue_a) { create(:issue) }
+    let_it_be(:issue_b) { create(:issue) }
+
+    let_it_be(:design_a) { create(:design, issue: issue_a) }
+    let_it_be(:design_b) { create(:design, issue: issue_a) }
+    let_it_be(:design_c) { create(:design, issue: issue_b, filename: design_a.filename) }
+    let_it_be(:design_d) { create(:design, issue: issue_b, filename: design_b.filename) }
+
+    it_behaves_like 'a where_composite scope', :by_issue_id_and_filename do
+      let(:all_results) { [design_a, design_b, design_c, design_d] }
+      let(:first_result) { design_a }
+
+      let(:composite_ids) do
+        all_results.map { |design| { issue_id: design.issue_id, filename: design.filename } }
+      end
+    end
+  end
+end
diff --git a/spec/models/design_management/repository_spec.rb b/spec/models/design_management/repository_spec.rb
new file mode 100644
index 00000000000..996316eeec9
--- /dev/null
+++ b/spec/models/design_management/repository_spec.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DesignManagement::Repository do
+  let(:project) { create(:project) }
+  let(:repository) { described_class.new(project) }
+
+  shared_examples 'returns parsed git attributes that enable LFS for all file types' do
+    it do
+      expect(subject.patterns).to be_a_kind_of(Hash)
+      expect(subject.patterns).to have_key('/designs/*')
+      expect(subject.patterns['/designs/*']).to eql(
+        { "filter" => "lfs", "diff" => "lfs", "merge" => "lfs", "text" => false }
+      )
+    end
+  end
+
+  describe "#info_attributes" do
+    subject { repository.info_attributes }
+
+    include_examples 'returns parsed git attributes that enable LFS for all file types'
+  end
+
+  describe '#attributes_at' do
+    subject { repository.attributes_at }
+
+    include_examples 'returns parsed git attributes that enable LFS for all file types'
+  end
+
+  describe '#gitattribute' do
+    it 'returns a gitattribute when path has gitattributes' do
+      expect(repository.gitattribute('/designs/file.txt', 'filter')).to eq('lfs')
+    end
+
+    it 'returns nil when path has no gitattributes' do
+      expect(repository.gitattribute('/invalid/file.txt', 'filter')).to be_nil
+    end
+  end
+
+  describe '#copy_gitattributes' do
+    it 'always returns regardless of whether given a valid or invalid ref' do
+      expect(repository.copy_gitattributes('master')).to be true
+      expect(repository.copy_gitattributes('invalid')).to be true
+    end
+  end
+
+  describe '#attributes' do
+    it 'confirms that all files are LFS enabled' do
+      %w(png zip anything).each do |filetype|
+        path = "/#{DesignManagement.designs_directory}/file.#{filetype}"
+        attributes = repository.attributes(path)
+
+        expect(attributes['filter']).to eq('lfs')
+      end
+    end
+  end
+end
diff --git a/spec/models/design_management/version_spec.rb b/spec/models/design_management/version_spec.rb
new file mode 100644
index 00000000000..ab6958ea94a
--- /dev/null
+++ b/spec/models/design_management/version_spec.rb
@@ -0,0 +1,342 @@
+# frozen_string_literal: true
+require 'spec_helper'
+
+describe DesignManagement::Version do
+  let_it_be(:issue) { create(:issue) }
+
+  describe 'relations' do
+    it { is_expected.to have_many(:actions) }
+    it { is_expected.to have_many(:designs).through(:actions) }
+
+    it 'constrains the designs relation correctly' do
+      design = create(:design)
+      version = create(:design_version, designs: [design])
+
+      expect { version.designs << design }.to raise_error(ActiveRecord::RecordNotUnique)
+    end
+
+    it 'allows adding multiple versions to a single design' do
+      design = create(:design)
+      versions = create_list(:design_version, 2)
+
+      expect { versions.each { |v| design.versions << v } }
+        .not_to raise_error
+    end
+  end
+
+  describe 'validations' do
+    subject(:design_version) { build(:design_version) }
+
+    it { is_expected.to be_valid }
+    it { is_expected.to validate_presence_of(:author) }
+    it { is_expected.to validate_presence_of(:sha) }
+    it { is_expected.to validate_presence_of(:designs) }
+    it { is_expected.to validate_presence_of(:issue_id) }
+    it { is_expected.to validate_uniqueness_of(:sha).scoped_to(:issue_id).case_insensitive }
+  end
+
+  describe "scopes" do
+    let_it_be(:version_1) { create(:design_version) }
+    let_it_be(:version_2) { create(:design_version) }
+
+    describe ".for_designs" do
+      it "only returns versions related to the specified designs" do
+        _other_version = create(:design_version)
+        designs = [create(:design, versions: [version_1]),
+                   create(:design, versions: [version_2])]
+
+        expect(described_class.for_designs(designs))
+          .to contain_exactly(version_1, version_2)
+      end
+    end
+
+    describe '.earlier_or_equal_to' do
+      it 'only returns versions created earlier or later than the given version' do
+        expect(described_class.earlier_or_equal_to(version_1)).to eq([version_1])
+        expect(described_class.earlier_or_equal_to(version_2)).to contain_exactly(version_1, version_2)
+      end
+
+      it 'can be passed either a DesignManagement::Version or an ID' do
+        [version_1, version_1.id].each do |arg|
+          expect(described_class.earlier_or_equal_to(arg)).to eq([version_1])
+        end
+      end
+    end
+
+    describe '.by_sha' do
+      it 'can find versions by sha' do
+        [version_1, version_2].each do |version|
+          expect(described_class.by_sha(version.sha)).to contain_exactly(version)
+        end
+      end
+    end
+  end
+
+  describe ".create_for_designs" do
+    def current_version_id(design)
+      design.send(:head_version).try(:id)
+    end
+
+    def as_actions(designs, action = :create)
+      designs.map do |d|
+        DesignManagement::DesignAction.new(d, action, action == :delete ? nil : :content)
+      end
+    end
+
+    let_it_be(:author) { create(:user) }
+    let_it_be(:design_a) { create(:design, issue: issue) }
+    let_it_be(:design_b) { create(:design, issue: issue) }
+    let_it_be(:designs) { [design_a, design_b] }
+
+    describe 'the error raised when there are no actions' do
+      let_it_be(:sha) { 'f00' }
+
+      def call_with_empty_actions
+        described_class.create_for_designs([], sha, author)
+      end
+
+      it 'raises CouldNotCreateVersion' do
+        expect { call_with_empty_actions }
+          .to raise_error(described_class::CouldNotCreateVersion)
+      end
+
+      it 'has an appropriate cause' do
+        expect { call_with_empty_actions }
+          .to raise_error(have_attributes(cause: ActiveRecord::RecordInvalid))
+      end
+
+      it 'provides extra data sentry can consume' do
+        extra_info = a_hash_including(sha: sha)
+
+        expect { call_with_empty_actions }
+          .to raise_error(have_attributes(sentry_extra_data: extra_info))
+      end
+    end
+
+    describe 'the error raised when the designs come from different issues' do
+      let_it_be(:sha) { 'f00' }
+      let_it_be(:designs) { create_list(:design, 2) }
+      let_it_be(:actions) { as_actions(designs) }
+
+      def call_with_mismatched_designs
+        described_class.create_for_designs(actions, sha, author)
+      end
+
+      it 'raises CouldNotCreateVersion' do
+        expect { call_with_mismatched_designs }
+          .to raise_error(described_class::CouldNotCreateVersion)
+      end
+
+      it 'has an appropriate cause' do
+        expect { call_with_mismatched_designs }
+          .to raise_error(have_attributes(cause: described_class::NotSameIssue))
+      end
+
+      it 'provides extra data sentry can consume' do
+        extra_info = a_hash_including(design_ids: designs.map(&:id))
+
+        expect { call_with_mismatched_designs }
+          .to raise_error(have_attributes(sentry_extra_data: extra_info))
+      end
+    end
+
+    it 'does not leave invalid versions around if creation fails' do
+      expect do
+        described_class.create_for_designs([], 'abcdef', author) rescue nil
+      end.not_to change { described_class.count }
+    end
+
+    it 'does not leave orphaned design-versions around if creation fails' do
+      actions = as_actions(designs)
+      expect do
+        described_class.create_for_designs(actions, '', author) rescue nil
+      end.not_to change { DesignManagement::Action.count }
+    end
+
+    it 'creates a version and links it to multiple designs' do
+      actions = as_actions(designs, :create)
+
+      version = described_class.create_for_designs(actions, 'abc', author)
+
+      expect(version.designs).to contain_exactly(*designs)
+      expect(designs.map(&method(:current_version_id))).to all(eq version.id)
+    end
+
+    it 'creates designs if they are new to git' do
+      actions = as_actions(designs, :create)
+
+      described_class.create_for_designs(actions, 'abc', author)
+
+      expect(designs.map(&:most_recent_action)).to all(be_creation)
+    end
+
+    it 'correctly associates the version with the issue' do
+      actions = as_actions(designs)
+
+      version = described_class.create_for_designs(actions, 'abc', author)
+
+      expect(version.issue).to eq(issue)
+    end
+
+    it 'correctly associates the version with the author' do
+      actions = as_actions(designs)
+
+      version = described_class.create_for_designs(actions, 'abc', author)
+
+      expect(version.author).to eq(author)
+    end
+
+    it 'modifies designs if git updated them' do
+      actions = as_actions(designs, :update)
+
+      described_class.create_for_designs(actions, 'abc', author)
+
+      expect(designs.map(&:most_recent_action)).to all(be_modification)
+    end
+
+    it 'deletes designs when the git action was delete' do
+      actions = as_actions(designs, :delete)
+
+      described_class.create_for_designs(actions, 'def', author)
+
+      expect(designs).to all(be_deleted)
+    end
+
+    it 're-creates designs if they are deleted' do
+      described_class.create_for_designs(as_actions(designs, :create), 'abc', author)
+      described_class.create_for_designs(as_actions(designs, :delete), 'def', author)
+
+      expect(designs).to all(be_deleted)
+
+      described_class.create_for_designs(as_actions(designs, :create), 'ghi', author)
+
+      expect(designs.map(&:most_recent_action)).to all(be_creation)
+      expect(designs).not_to include(be_deleted)
+    end
+
+    it 'changes the version of the designs' do
+      actions = as_actions([design_a])
+      described_class.create_for_designs(actions, 'before', author)
+
+      expect do
+        described_class.create_for_designs(actions, 'after', author)
+      end.to change { current_version_id(design_a) }
+    end
+  end
+
+  describe '#designs_by_event' do
+    context 'there is a single design' do
+      let_it_be(:design) { create(:design) }
+
+      shared_examples :a_correctly_categorised_design do |kind, category|
+        let_it_be(:version) { create(:design_version, kind => [design]) }
+
+        it 'returns a hash with a single key and the single design in that bucket' do
+          expect(version.designs_by_event).to eq(category => [design])
+        end
+      end
+
+      it_behaves_like :a_correctly_categorised_design, :created_designs, 'creation'
+      it_behaves_like :a_correctly_categorised_design, :modified_designs, 'modification'
+      it_behaves_like :a_correctly_categorised_design, :deleted_designs, 'deletion'
+    end
+
+    context 'there are a bunch of different designs in a variety of states' do
+      let_it_be(:version) do
+        create(:design_version,
+               created_designs: create_list(:design, 3),
+               modified_designs: create_list(:design, 4),
+               deleted_designs: create_list(:design, 5))
+      end
+
+      it 'puts them in the right buckets' do
+        expect(version.designs_by_event).to match(
+          a_hash_including(
+            'creation' =>  have_attributes(size: 3),
+            'modification' => have_attributes(size: 4),
+            'deletion' => have_attributes(size: 5)
+          )
+        )
+      end
+
+      it 'does not suffer from N+1 queries' do
+        version.designs.map(&:id) # we don't care about the set-up queries
+        expect { version.designs_by_event }.not_to exceed_query_limit(2)
+      end
+    end
+  end
+
+  describe '#author' do
+    it 'returns the author' do
+      author = build(:user)
+      version = build(:design_version, author: author)
+
+      expect(version.author).to eq(author)
+    end
+
+    it 'returns nil if author_id is nil and version is not persisted' do
+      version = build(:design_version, author: nil)
+
+      expect(version.author).to eq(nil)
+    end
+
+    it 'retrieves author from the Commit if author_id is nil and version has been persisted' do
+      author = create(:user)
+      version = create(:design_version, :committed, author: author)
+      author.destroy
+      version.reload
+      commit = version.issue.project.design_repository.commit(version.sha)
+      commit_user = create(:user, email: commit.author_email, name: commit.author_name)
+
+      expect(version.author_id).to eq(nil)
+      expect(version.author).to eq(commit_user)
+    end
+  end
+
+  describe '#diff_refs' do
+    let(:project) { issue.project }
+
+    before do
+      expect(project.design_repository).to receive(:commit)
+        .once
+        .with(sha)
+        .and_return(commit)
+    end
+
+    subject { create(:design_version, issue: issue, sha: sha) }
+
+    context 'there is a commit in the repo by the SHA' do
+      let(:commit) { build(:commit) }
+      let(:sha) { commit.id }
+
+      it { is_expected.to have_attributes(diff_refs: commit.diff_refs) }
+
+      it 'memoizes calls to #diff_refs' do
+        expect(subject.diff_refs).to eq(subject.diff_refs)
+      end
+    end
+
+    context 'there is no commit in the repo by the SHA' do
+      let(:commit) { nil }
+      let(:sha) { Digest::SHA1.hexdigest("points to nothing") }
+
+      it { is_expected.to have_attributes(diff_refs: be_nil) }
+    end
+  end
+
+  describe '#reset' do
+    subject { create(:design_version, issue: issue) }
+
+    it 'removes memoized values' do
+      expect(subject).to receive(:commit).twice.and_return(nil)
+
+      subject.diff_refs
+      subject.diff_refs
+
+      subject.reset
+
+      subject.diff_refs
+      subject.diff_refs
+    end
+  end
+end
diff --git a/spec/models/design_user_mention_spec.rb b/spec/models/design_user_mention_spec.rb
new file mode 100644
index 00000000000..03c77c73c8d
--- /dev/null
+++ b/spec/models/design_user_mention_spec.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DesignUserMention do
+  describe 'associations' do
+    it { is_expected.to belong_to(:design) }
+    it { is_expected.to belong_to(:note) }
+  end
+
+  it_behaves_like 'has user mentions'
+end
diff --git a/spec/models/diff_note_spec.rb b/spec/models/diff_note_spec.rb
index b802c8ba506..65f06a5b270 100644
--- a/spec/models/diff_note_spec.rb
+++ b/spec/models/diff_note_spec.rb
@@ -287,6 +287,24 @@ describe DiffNote do
         reply_diff_note.reload.diff_file
       end
     end
+
+    context 'when noteable is a Design' do
+      it 'does not return a diff file' do
+        diff_note = create(:diff_note_on_design)
+
+        expect(diff_note.diff_file).to be_nil
+      end
+    end
+  end
+
+  describe '#latest_diff_file' do
+    context 'when noteable is a Design' do
+      it 'does not return a diff file' do
+        diff_note = create(:diff_note_on_design)
+
+        expect(diff_note.latest_diff_file).to be_nil
+      end
+    end
   end
 
   describe "#diff_line" do
diff --git a/spec/models/issue_spec.rb b/spec/models/issue_spec.rb
index 375c8c1546f..cc7dffb93d2 100644
--- a/spec/models/issue_spec.rb
+++ b/spec/models/issue_spec.rb
@@ -15,8 +15,20 @@ describe Issue do
     it { is_expected.to belong_to(:closed_by).class_name('User') }
     it { is_expected.to have_many(:assignees) }
     it { is_expected.to have_many(:user_mentions).class_name("IssueUserMention") }
+    it { is_expected.to have_many(:designs) }
+    it { is_expected.to have_many(:design_versions) }
     it { is_expected.to have_one(:sentry_issue) }
     it { is_expected.to have_one(:alert_management_alert) }
+
+    describe 'versions.most_recent' do
+      it 'returns the most recent version' do
+        issue = create(:issue)
+        create_list(:design_version, 2, issue: issue)
+        last_version = create(:design_version, issue: issue)
+
+        expect(issue.design_versions.most_recent).to eq(last_version)
+      end
+    end
   end
 
   describe 'modules' do
@@ -970,4 +982,48 @@ describe Issue do
       expect(issue.previous_updated_at).to eq(Time.new(2013, 02, 06))
     end
   end
+
+  describe '#design_collection' do
+    it 'returns a design collection' do
+      issue = build(:issue)
+      collection = issue.design_collection
+
+      expect(collection).to be_a(DesignManagement::DesignCollection)
+      expect(collection.issue).to eq(issue)
+    end
+  end
+
+  describe 'current designs' do
+    let(:issue) { create(:issue) }
+
+    subject { issue.designs.current }
+
+    context 'an issue has no designs' do
+      it { is_expected.to be_empty }
+    end
+
+    context 'an issue only has current designs' do
+      let!(:design_a) { create(:design, :with_file, issue: issue) }
+      let!(:design_b) { create(:design, :with_file, issue: issue) }
+      let!(:design_c) { create(:design, :with_file, issue: issue) }
+
+      it { is_expected.to include(design_a, design_b, design_c) }
+    end
+
+    context 'an issue only has deleted designs' do
+      let!(:design_a) { create(:design, :with_file, issue: issue, deleted: true) }
+      let!(:design_b) { create(:design, :with_file, issue: issue, deleted: true) }
+      let!(:design_c) { create(:design, :with_file, issue: issue, deleted: true) }
+
+      it { is_expected.to be_empty }
+    end
+
+    context 'an issue has a mixture of current and deleted designs' do
+      let!(:design_a) { create(:design, :with_file, issue: issue) }
+      let!(:design_b) { create(:design, :with_file, issue: issue, deleted: true) }
+      let!(:design_c) { create(:design, :with_file, issue: issue) }
+
+      it { is_expected.to contain_exactly(design_a, design_c) }
+    end
+  end
 end
diff --git a/spec/models/note_spec.rb b/spec/models/note_spec.rb
index 74ec74e0def..4900743ccb5 100644
--- a/spec/models/note_spec.rb
+++ b/spec/models/note_spec.rb
@@ -751,6 +751,14 @@ describe Note do
     end
   end
 
+  describe '#for_design' do
+    it 'is true when the noteable is a design' do
+      note = build(:note, noteable: build(:design))
+
+      expect(note).to be_for_design
+    end
+  end
+
   describe '#to_ability_name' do
     it 'returns note' do
       expect(build(:note).to_ability_name).to eq('note')
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 78c0e8aef1a..bcd28538e2c 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -6,6 +6,7 @@ describe Project do
   include ProjectForksHelper
   include GitHelpers
   include ExternalAuthorizationServiceHelpers
+  using RSpec::Parameterized::TableSyntax
 
   it_behaves_like 'having unique enum values'
 
@@ -6058,6 +6059,28 @@ describe Project do
     end
   end
 
+  describe '#design_management_enabled?' do
+    let(:project) { build(:project) }
+
+    where(:lfs_enabled, :hashed_storage_enabled, :expectation) do
+      false | false | false
+      true  | false | false
+      false | true  | false
+      true  | true  | true
+    end
+
+    with_them do
+      before do
+        expect(project).to receive(:lfs_enabled?).and_return(lfs_enabled)
+        allow(project).to receive(:hashed_storage?).with(:repository).and_return(hashed_storage_enabled)
+      end
+
+      it do
+        expect(project.design_management_enabled?).to be(expectation)
+      end
+    end
+  end
+
   def finish_job(export_job)
     export_job.start
     export_job.finish
diff --git a/spec/services/design_management/design_user_notes_count_service_spec.rb b/spec/services/design_management/design_user_notes_count_service_spec.rb
new file mode 100644
index 00000000000..f4808542995
--- /dev/null
+++ b/spec/services/design_management/design_user_notes_count_service_spec.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DesignManagement::DesignUserNotesCountService, :use_clean_rails_memory_store_caching do
+  let_it_be(:design) { create(:design, :with_file) }
+
+  subject { described_class.new(design) }
+
+  it_behaves_like 'a counter caching service'
+
+  describe '#count' do
+    it 'returns the count of notes' do
+      create_list(:diff_note_on_design, 3, noteable: design)
+
+      expect(subject.count).to eq(3)
+    end
+  end
+
+  describe '#cache_key' do
+    it 'contains the `VERSION` and `design.id`' do
+      expect(subject.cache_key).to eq(['designs', 'notes_count', DesignManagement::DesignUserNotesCountService::VERSION, design.id])
+    end
+  end
+
+  # TODO These tests are being temporarily skipped unless run in EE,
+  # as we are in the process of moving Design Management to FOSS in 13.0
+  # in steps. In the current step the services have not yet been moved.
+  #
+  # See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283.
+  describe 'cache invalidation' do
+    it 'changes when a new note is created' do
+      skip 'See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283' unless Gitlab.ee?
+
+      new_note_attrs = attributes_for(:diff_note_on_design, noteable: design)
+
+      expect do
+        Notes::CreateService.new(design.project, create(:user), new_note_attrs).execute
+      end.to change { subject.count }.by(1)
+    end
+
+    it 'changes when a note is destroyed' do
+      skip 'See https://gitlab.com/gitlab-org/gitlab/-/issues/212566#note_327724283' unless Gitlab.ee?
+
+      note = create(:diff_note_on_design, noteable: design)
+
+      expect do
+        Notes::DestroyService.new(note.project, note.author).execute(note)
+      end.to change { subject.count }.by(-1)
+    end
+  end
+end
diff --git a/spec/services/issues/related_branches_service_spec.rb b/spec/services/issues/related_branches_service_spec.rb
index eae35f12560..9f72e499414 100644
--- a/spec/services/issues/related_branches_service_spec.rb
+++ b/spec/services/issues/related_branches_service_spec.rb
@@ -3,39 +3,103 @@
 require 'spec_helper'
 
 describe Issues::RelatedBranchesService do
-  let(:user) { create(:admin) }
-  let(:issue) { create(:issue) }
+  let_it_be(:developer) { create(:user) }
+  let_it_be(:issue) { create(:issue) }
+  let(:user) { developer }
 
   subject { described_class.new(issue.project, user) }
 
+  before do
+    issue.project.add_developer(developer)
+  end
+
   describe '#execute' do
+    let(:sha) { 'abcdef' }
+    let(:repo) { issue.project.repository }
+    let(:project) { issue.project }
+    let(:branch_info) { subject.execute(issue) }
+
+    def make_branch
+      double('Branch', dereferenced_target: double('Target', sha: sha))
+    end
+
     before do
-      allow(issue.project.repository).to receive(:branch_names).and_return(["mpempe", "#{issue.iid}mepmep", issue.to_branch_name, "#{issue.iid}-branch"])
+      allow(repo).to receive(:branch_names).and_return(branch_names)
     end
 
-    it "selects the right branches when there are no referenced merge requests" do
-      expect(subject.execute(issue)).to eq([issue.to_branch_name, "#{issue.iid}-branch"])
+    context 'no branches are available' do
+      let(:branch_names) { [] }
+
+      it 'returns an empty array' do
+        expect(branch_info).to be_empty
+      end
     end
 
-    it "selects the right branches when there is a referenced merge request" do
-      merge_request = create(:merge_request, { description: "Closes ##{issue.iid}",
-                                               source_project: issue.project,
-                                               source_branch: "#{issue.iid}-branch" })
-      merge_request.create_cross_references!(user)
+    context 'branches are available' do
+      let(:missing_branch) { "#{issue.to_branch_name}-missing" }
+      let(:unreadable_branch_name) { "#{issue.to_branch_name}-unreadable" }
+      let(:pipeline) { build(:ci_pipeline, :success, project: project) }
+      let(:unreadable_pipeline) { build(:ci_pipeline, :running) }
+
+      let(:branch_names) do
+        [
+          generate(:branch),
+          "#{issue.iid}doesnt-match",
+          issue.to_branch_name,
+          missing_branch,
+          unreadable_branch_name
+        ]
+      end
+
+      before do
+        {
+          issue.to_branch_name => pipeline,
+          unreadable_branch_name => unreadable_pipeline
+        }.each do |name, pipeline|
+          allow(repo).to receive(:find_branch).with(name).and_return(make_branch)
+          allow(project).to receive(:pipeline_for).with(name, sha).and_return(pipeline)
+        end
+
+        allow(repo).to receive(:find_branch).with(missing_branch).and_return(nil)
+      end
+
+      it 'selects relevant branches, along with pipeline status where available' do
+        expect(branch_info).to contain_exactly(
+          { name: issue.to_branch_name, pipeline_status: an_instance_of(Gitlab::Ci::Status::Success) },
+          { name: missing_branch, pipeline_status: be_nil },
+          { name: unreadable_branch_name, pipeline_status: be_nil }
+        )
+      end
+
+      context 'the user has access to otherwise unreadable pipelines' do
+        let(:user) { create(:admin) }
+
+        it 'returns info a developer could not see' do
+          expect(branch_info.pluck(:pipeline_status)).to include(an_instance_of(Gitlab::Ci::Status::Running))
+        end
+      end
+
+      it 'excludes branches referenced in merge requests' do
+        merge_request = create(:merge_request, { description: "Closes #{issue.to_reference}",
+                                                 source_project: issue.project,
+                                                 source_branch: issue.to_branch_name })
+        merge_request.create_cross_references!(user)
 
-      referenced_merge_requests = Issues::ReferencedMergeRequestsService
-                                    .new(issue.project, user)
-                                    .referenced_merge_requests(issue)
+        referenced_merge_requests = Issues::ReferencedMergeRequestsService
+                                      .new(issue.project, user)
+                                      .referenced_merge_requests(issue)
 
-      expect(referenced_merge_requests).not_to be_empty
-      expect(subject.execute(issue)).to eq([issue.to_branch_name])
+        expect(referenced_merge_requests).not_to be_empty
+        expect(branch_info.pluck(:name)).not_to include(merge_request.source_branch)
+      end
     end
 
-    it 'excludes stable branches from the related branches' do
-      allow(issue.project.repository).to receive(:branch_names)
-        .and_return(["#{issue.iid}-0-stable"])
+    context 'one of the branches is stable' do
+      let(:branch_names) { ["#{issue.iid}-0-stable"] }
 
-      expect(subject.execute(issue)).to eq []
+      it 'is excluded' do
+        expect(branch_info).to be_empty
+      end
     end
   end
 end
diff --git a/spec/support/helpers/design_management_test_helpers.rb b/spec/support/helpers/design_management_test_helpers.rb
new file mode 100644
index 00000000000..bf41e2f5079
--- /dev/null
+++ b/spec/support/helpers/design_management_test_helpers.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module DesignManagementTestHelpers
+  def enable_design_management(enabled = true, ref_filter = true)
+    stub_lfs_setting(enabled: enabled)
+    stub_feature_flags(design_management_reference_filter_gfm_pipeline: ref_filter)
+  end
+
+  def delete_designs(*designs)
+    act_on_designs(designs) { ::DesignManagement::Action.deletion }
+  end
+
+  def restore_designs(*designs)
+    act_on_designs(designs) { ::DesignManagement::Action.creation }
+  end
+
+  def modify_designs(*designs)
+    act_on_designs(designs) { ::DesignManagement::Action.modification }
+  end
+
+  def path_for_design(design)
+    path_options = { vueroute: design.filename }
+    Gitlab::Routing.url_helpers.designs_project_issue_path(design.project, design.issue, path_options)
+  end
+
+  def url_for_design(design)
+    path_options = { vueroute: design.filename }
+    Gitlab::Routing.url_helpers.designs_project_issue_url(design.project, design.issue, path_options)
+  end
+
+  def url_for_designs(issue)
+    Gitlab::Routing.url_helpers.designs_project_issue_url(issue.project, issue)
+  end
+
+  private
+
+  def act_on_designs(designs, &block)
+    issue = designs.first.issue
+    version = build(:design_version, :empty, issue: issue).tap { |v| v.save(validate: false) }
+    designs.each do |d|
+      yield.create(design: d, version: version)
+    end
+    version
+  end
+end
diff --git a/spec/uploaders/design_management/design_v432x230_uploader_spec.rb b/spec/uploaders/design_management/design_v432x230_uploader_spec.rb
new file mode 100644
index 00000000000..8c62b6ad6a8
--- /dev/null
+++ b/spec/uploaders/design_management/design_v432x230_uploader_spec.rb
@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DesignManagement::DesignV432x230Uploader do
+  include CarrierWave::Test::Matchers
+
+  let(:model) { create(:design_action, :with_image_v432x230) }
+  let(:upload) { create(:upload, :design_action_image_v432x230_upload, model: model) }
+
+  subject(:uploader) { described_class.new(model, :image_v432x230) }
+
+  it_behaves_like 'builds correct paths',
+                  store_dir: %r[uploads/-/system/design_management/action/image_v432x230/],
+                  upload_path: %r[uploads/-/system/design_management/action/image_v432x230/],
+                  relative_path: %r[uploads/-/system/design_management/action/image_v432x230/],
+                  absolute_path: %r[#{CarrierWave.root}/uploads/-/system/design_management/action/image_v432x230/]
+
+  context 'object_store is REMOTE' do
+    before do
+      stub_uploads_object_storage
+    end
+
+    include_context 'with storage', described_class::Store::REMOTE
+
+    it_behaves_like 'builds correct paths',
+                    store_dir: %r[design_management/action/image_v432x230/],
+                    upload_path: %r[design_management/action/image_v432x230/],
+                    relative_path: %r[design_management/action/image_v432x230/]
+  end
+
+  describe "#migrate!" do
+    before do
+      uploader.store!(fixture_file_upload('spec/fixtures/dk.png'))
+      stub_uploads_object_storage
+    end
+
+    it_behaves_like 'migrates', to_store: described_class::Store::REMOTE
+    it_behaves_like 'migrates', from_store: described_class::Store::REMOTE, to_store: described_class::Store::LOCAL
+  end
+
+  it 'resizes images', :aggregate_failures do
+    image_loader = CarrierWave::Test::Matchers::ImageLoader
+    original_file = fixture_file_upload('spec/fixtures/dk.png')
+    uploader.store!(original_file)
+
+    expect(
+      image_loader.load_image(original_file.tempfile.path)
+    ).to have_attributes(
+      width: 460,
+      height: 322
+    )
+    expect(
+      image_loader.load_image(uploader.file.file)
+    ).to have_attributes(
+      width: 329,
+      height: 230
+    )
+  end
+
+  context 'accept whitelist file content type' do
+    # We need to feed through a valid path, but we force the parsed mime type
+    # in a stub below so we can set any path.
+    let_it_be(:path) { File.join('spec', 'fixtures', 'dk.png') }
+
+    where(:mime_type) { described_class::MIME_TYPE_WHITELIST }
+
+    with_them do
+      include_context 'force content type detection to mime_type'
+
+      it_behaves_like 'accepted carrierwave upload'
+    end
+  end
+
+  context 'upload non-whitelisted file content type' do
+    let_it_be(:path) { File.join('spec', 'fixtures', 'logo_sample.svg') }
+
+    it_behaves_like 'denied carrierwave upload'
+  end
+
+  context 'upload misnamed non-whitelisted file content type' do
+    let_it_be(:path) { File.join('spec', 'fixtures', 'not_a_png.png') }
+
+    it_behaves_like 'denied carrierwave upload'
+  end
+end
diff --git a/spec/views/projects/issues/_related_branches.html.haml_spec.rb b/spec/views/projects/issues/_related_branches.html.haml_spec.rb
index a6817e3fdbf..6c9bbaea38c 100644
--- a/spec/views/projects/issues/_related_branches.html.haml_spec.rb
+++ b/spec/views/projects/issues/_related_branches.html.haml_spec.rb
@@ -5,23 +5,25 @@ require 'spec_helper'
 describe 'projects/issues/_related_branches' do
   include Devise::Test::ControllerHelpers
 
-  let(:user) { create(:user) }
-  let(:project) { create(:project, :repository) }
-  let(:branch) { project.repository.find_branch('feature') }
-  let!(:pipeline) { create(:ci_pipeline, project: project, sha: branch.dereferenced_target.id, ref: 'feature') }
+  let(:pipeline) { build(:ci_pipeline, :success) }
+  let(:status) { pipeline.detailed_status(build(:user)) }
 
   before do
-    assign(:project, project)
-    assign(:related_branches, ['feature'])
-
-    project.add_developer(user)
-    allow(view).to receive(:current_user).and_return(user)
+    assign(:related_branches, [
+      { name: 'other', link: 'link-to-other', pipeline_status: nil },
+      { name: 'feature', link: 'link-to-feature', pipeline_status: status }
+    ])
 
     render
   end
 
-  it 'shows the related branches with their build status' do
-    expect(rendered).to match('feature')
+  it 'shows the related branches with their build status', :aggregate_failures do
+    expect(rendered).to have_text('feature')
+    expect(rendered).to have_text('other')
+    expect(rendered).to have_link(href: 'link-to-feature')
+    expect(rendered).to have_link(href: 'link-to-other')
     expect(rendered).to have_css('.related-branch-ci-status')
+    expect(rendered).to have_css('.ci-status-icon')
+    expect(rendered).to have_css('.related-branch-info')
   end
 end