Use CTEs for nested groups and authorizations

This commit introduces the usage of Common Table Expressions (CTEs) to
efficiently retrieve nested group hierarchies, without having to rely on
the "routes" table (which is an _incredibly_ inefficient way of getting
the data). This requires a patch to ActiveRecord (found in the added
initializer) to work properly as ActiveRecord doesn't support WITH
statements properly out of the box.

Unfortunately MySQL provides no efficient way of getting nested groups.
For example, the old routes setup could easily take 5-10 seconds
depending on the amount of "routes" in a database. Providing vastly
different logic for both MySQL and PostgreSQL will negatively impact the
development process. Because of this the various nested groups related
methods return empty relations when used in combination with MySQL.

For project authorizations the logic is split up into two classes:

* Gitlab::ProjectAuthorizations::WithNestedGroups
* Gitlab::ProjectAuthorizations::WithoutNestedGroups

Both classes get the fresh project authorizations (= as they should be
in the "project_authorizations" table), including nested groups if
PostgreSQL is used. The logic of these two classes is quite different
apart from their public interface. This complicates development a bit,
but unfortunately there is no way around this.

This commit also introduces Gitlab::GroupHierarchy. This class can be
used to get the ancestors and descendants of a base relation, or both by
using a UNION. This in turn is used by methods such as:

* Namespace#ancestors
* Namespace#descendants
* User#all_expanded_groups

Again this class relies on CTEs and thus only works on PostgreSQL. The
Namespace methods will return an empty relation when MySQL is used,
while User#all_expanded_groups will return only the groups a user is a
direct member of.

Performance wise the impact is quite large. For example, on GitLab.com
Namespace#descendants used to take around 580 ms to retrieve data for a
particular user. Using CTEs we are able to reduce this down to roughly 1
millisecond, returning the exact same data.

== On The Fly Refreshing

Refreshing of authorizations on the fly (= when
users.authorized_projects_populated was not set) is removed with this
commit. This simplifies the code, and ensures any queries used for
authorizations are not mutated because they are executed in a Rails
scope (e.g. Project.visible_to_user).

This commit includes a migration to schedule refreshing authorizations
for all users, ensuring all of them have their authorizations in place.
Said migration schedules users in batches of 5000, with 5 minutes
between every batch to smear the load around a bit.

== Spec Changes

This commit also introduces some changes to various specs. For example,
some specs for ProjectTeam assumed that creating a personal project
would _not_ lead to the owner having access, which is incorrect. Because
we also no longer refresh authorizations on the fly for new users some
code had to be added to the "empty_project" factory. This chunk of code
ensures that the owner's permissions are refreshed after creating the
project, something that is normally done in Projects::CreateService.

36 files changed, 386 insertions, 309 deletions

diff --git a/spec/controllers/autocomplete_controller_spec.rb b/spec/controllers/autocomplete_controller_spec.rb
index 7d2f6dd9d0a..8247f81b7d0 100644
--- a/spec/controllers/autocomplete_controller_spec.rb
+++ b/spec/controllers/autocomplete_controller_spec.rb
@@ -22,7 +22,7 @@ describe AutocompleteController do
         let(:body) { JSON.parse(response.body) }
 
         it { expect(body).to be_kind_of(Array) }
-        it { expect(body.size).to eq 1 }
+        it { expect(body.size).to eq 2 }
         it { expect(body.map { |u| u["username"] }).to include(user.username) }
       end
 
@@ -80,8 +80,8 @@ describe AutocompleteController do
         end
 
         it { expect(body).to be_kind_of(Array) }
-        it { expect(body.size).to eq 2 }
-        it { expect(body.map { |u| u['username'] }).to match_array([user.username, non_member.username]) }
+        it { expect(body.size).to eq 3 }
+        it { expect(body.map { |u| u['username'] }).to include(user.username, non_member.username) }
       end
     end
 
@@ -108,7 +108,7 @@ describe AutocompleteController do
         end
 
         it { expect(body).to be_kind_of(Array) }
-        it { expect(body.size).to eq 1 }
+        it { expect(body.size).to eq 2 }
       end
 
       describe 'GET #users with project' do
diff --git a/spec/controllers/projects/merge_requests_controller_spec.rb b/spec/controllers/projects/merge_requests_controller_spec.rb
index 0b3492a8fed..85062c93a58 100644
--- a/spec/controllers/projects/merge_requests_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests_controller_spec.rb
@@ -2,7 +2,7 @@ require 'spec_helper'
 
 describe Projects::MergeRequestsController do
   let(:project) { create(:project) }
-  let(:user)    { create(:user) }
+  let(:user)    { project.owner }
   let(:merge_request) { create(:merge_request_with_diffs, target_project: project, source_project: project) }
   let(:merge_request_with_conflicts) do
     create(:merge_request, source_branch: 'conflict-resolvable', target_branch: 'conflict-start', source_project: project) do |mr|
@@ -12,7 +12,6 @@ describe Projects::MergeRequestsController do
 
   before do
     sign_in(user)
-    project.team << [user, :master]
   end
 
   describe 'GET new' do
@@ -292,6 +291,8 @@ describe Projects::MergeRequestsController do
     end
 
     context 'when user cannot access' do
+      let(:user) { create(:user) }
+
       before do
         project.add_reporter(user)
         xhr :post, :merge, base_params
@@ -448,6 +449,8 @@ describe Projects::MergeRequestsController do
   end
 
   describe "DELETE destroy" do
+    let(:user) { create(:user) }
+
     it "denies access to users unless they're admin or project owner" do
       delete :destroy, namespace_id: project.namespace, project_id: project, id: merge_request.iid
 
diff --git a/spec/factories/projects.rb b/spec/factories/projects.rb
index 3580752a805..574b52e760d 100644
--- a/spec/factories/projects.rb
+++ b/spec/factories/projects.rb
@@ -107,6 +107,18 @@ FactoryGirl.define do
           merge_requests_access_level: merge_requests_access_level,
           repository_access_level: evaluator.repository_access_level
         )
+
+      # Normally the class Projects::CreateService is used for creating
+      # projects, and this class takes care of making sure the owner and current
+      # user have access to the project. Our specs don't use said service class,
+      # thus we must manually refresh things here.
+      owner = project.owner
+
+      if owner && owner.is_a?(User) && !project.pending_delete
+        project.members.create!(user: owner, access_level: Gitlab::Access::MASTER)
+      end
+
+      project.group&.refresh_members_authorized_projects
     end
   end
 
diff --git a/spec/features/groups/group_name_toggle_spec.rb b/spec/features/groups/group_name_toggle_spec.rb
index 8a1d415c4f1..dfc3c84f29a 100644
--- a/spec/features/groups/group_name_toggle_spec.rb
+++ b/spec/features/groups/group_name_toggle_spec.rb
@@ -22,7 +22,7 @@ feature 'Group name toggle', feature: true, js: true do
     expect(page).not_to have_css('.group-name-toggle')
   end
 
-  it 'is present if the title is longer than the container' do
+  it 'is present if the title is longer than the container', :nested_groups do
     visit group_path(nested_group_3)
     title_width = page.evaluate_script("$('.title')[0].offsetWidth")
 
@@ -35,7 +35,7 @@ feature 'Group name toggle', feature: true, js: true do
     expect(title_width).to be > container_width
   end
 
-  it 'should show the full group namespace when toggled' do
+  it 'should show the full group namespace when toggled', :nested_groups do
     page_height = page.current_window.size[1]
     page.current_window.resize_to(SMALL_SCREEN, page_height)
     visit group_path(nested_group_3)
diff --git a/spec/features/groups/members/list_spec.rb b/spec/features/groups/members/list_spec.rb
index 543879bd21d..f654fa16a06 100644
--- a/spec/features/groups/members/list_spec.rb
+++ b/spec/features/groups/members/list_spec.rb
@@ -12,7 +12,7 @@ feature 'Groups members list', feature: true do
     login_as(user1)
   end
 
-  scenario 'show members from current group and parent' do
+  scenario 'show members from current group and parent', :nested_groups do
     group.add_developer(user1)
     nested_group.add_developer(user2)
 
@@ -22,7 +22,7 @@ feature 'Groups members list', feature: true do
     expect(second_row.text).to include(user2.name)
   end
 
-  scenario 'show user once if member of both current group and parent' do
+  scenario 'show user once if member of both current group and parent', :nested_groups do
     group.add_developer(user1)
     nested_group.add_developer(user1)
 
diff --git a/spec/features/groups_spec.rb b/spec/features/groups_spec.rb
index 3d32c47bf09..24ea7aba0cc 100644
--- a/spec/features/groups_spec.rb
+++ b/spec/features/groups_spec.rb
@@ -83,7 +83,7 @@ feature 'Group', feature: true do
     end
   end
 
-  describe 'create a nested group', js: true do
+  describe 'create a nested group', :nested_groups, js: true do
     let(:group) { create(:group, path: 'foo') }
 
     context 'as admin' do
@@ -196,7 +196,7 @@ feature 'Group', feature: true do
     end
   end
 
-  describe 'group page with nested groups', js: true do
+  describe 'group page with nested groups', :nested_groups, js: true do
     let!(:group) { create(:group) }
     let!(:nested_group) { create(:group, parent: group) }
     let!(:path)  { group_path(group) }
diff --git a/spec/features/issues/filtered_search/dropdown_assignee_spec.rb b/spec/features/issues/filtered_search/dropdown_assignee_spec.rb
index 0b573d7cef4..4d38df05928 100644
--- a/spec/features/issues/filtered_search/dropdown_assignee_spec.rb
+++ b/spec/features/issues/filtered_search/dropdown_assignee_spec.rb
@@ -58,7 +58,7 @@ describe 'Dropdown assignee', :feature, :js do
     it 'should load all the assignees when opened' do
       filtered_search.set('assignee:')
 
-      expect(dropdown_assignee_size).to eq(3)
+      expect(dropdown_assignee_size).to eq(4)
     end
 
     it 'shows current user at top of dropdown' do
diff --git a/spec/features/issues/filtered_search/dropdown_author_spec.rb b/spec/features/issues/filtered_search/dropdown_author_spec.rb
index 0579d6c80ab..8a43512fa3f 100644
--- a/spec/features/issues/filtered_search/dropdown_author_spec.rb
+++ b/spec/features/issues/filtered_search/dropdown_author_spec.rb
@@ -65,7 +65,7 @@ describe 'Dropdown author', js: true, feature: true do
     it 'should load all the authors when opened' do
       send_keys_to_filtered_search('author:')
 
-      expect(dropdown_author_size).to eq(3)
+      expect(dropdown_author_size).to eq(4)
     end
 
     it 'shows current user at top of dropdown' do
diff --git a/spec/features/projects/group_links_spec.rb b/spec/features/projects/group_links_spec.rb
index c969acc9140..4e5682c8636 100644
--- a/spec/features/projects/group_links_spec.rb
+++ b/spec/features/projects/group_links_spec.rb
@@ -40,7 +40,7 @@ feature 'Project group links', :feature, :js do
       another_group.add_master(master)
     end
 
-    it 'does not show ancestors' do
+    it 'does not show ancestors', :nested_groups do
       visit namespace_project_settings_members_path(project.namespace, project)
 
       click_link 'Search for a group'
diff --git a/spec/features/projects/members/sorting_spec.rb b/spec/features/projects/members/sorting_spec.rb
index b7ae5f0b925..d428f6fcf22 100644
--- a/spec/features/projects/members/sorting_spec.rb
+++ b/spec/features/projects/members/sorting_spec.rb
@@ -3,10 +3,9 @@ require 'spec_helper'
 feature 'Projects > Members > Sorting', feature: true do
   let(:master)    { create(:user, name: 'John Doe') }
   let(:developer) { create(:user, name: 'Mary Jane', last_sign_in_at: 5.days.ago) }
-  let(:project)   { create(:empty_project) }
+  let(:project)   { create(:empty_project, namespace: master.namespace, creator: master) }
 
   background do
-    create(:project_member, :master, user: master, project: project, created_at: 5.days.ago)
     create(:project_member, :developer, user: developer, project: project, created_at: 3.days.ago)
 
     login_as(master)
@@ -39,16 +38,16 @@ feature 'Projects > Members > Sorting', feature: true do
   scenario 'sorts by last joined' do
     visit_members_list(sort: :last_joined)
 
-    expect(first_member).to include(developer.name)
-    expect(second_member).to include(master.name)
+    expect(first_member).to include(master.name)
+    expect(second_member).to include(developer.name)
     expect(page).to have_css('.member-sort-dropdown .dropdown-toggle-text', text: 'Last joined')
   end
 
   scenario 'sorts by oldest joined' do
     visit_members_list(sort: :oldest_joined)
 
-    expect(first_member).to include(master.name)
-    expect(second_member).to include(developer.name)
+    expect(first_member).to include(developer.name)
+    expect(second_member).to include(master.name)
     expect(page).to have_css('.member-sort-dropdown .dropdown-toggle-text', text: 'Oldest joined')
   end
 
diff --git a/spec/features/projects/members/user_requests_access_spec.rb b/spec/features/projects/members/user_requests_access_spec.rb
index 1bf8f710b9f..ec48a4bd726 100644
--- a/spec/features/projects/members/user_requests_access_spec.rb
+++ b/spec/features/projects/members/user_requests_access_spec.rb
@@ -2,11 +2,10 @@ require 'spec_helper'
 
 feature 'Projects > Members > User requests access', feature: true do
   let(:user) { create(:user) }
-  let(:master) { create(:user) }
   let(:project) { create(:project, :public, :access_requestable) }
+  let(:master) { project.owner }
 
   background do
-    project.team << [master, :master]
     login_as(user)
     visit namespace_project_path(project.namespace, project)
   end
diff --git a/spec/finders/group_members_finder_spec.rb b/spec/finders/group_members_finder_spec.rb
index b762756f9ce..db3fcc23475 100644
--- a/spec/finders/group_members_finder_spec.rb
+++ b/spec/finders/group_members_finder_spec.rb
@@ -18,7 +18,7 @@ describe GroupMembersFinder, '#execute' do
     expect(result.to_a).to eq([member3, member2, member1])
   end
 
-  it 'returns members for nested group' do
+  it 'returns members for nested group', :nested_groups do
     group.add_master(user2)
     nested_group.request_access(user4)
     member1 = group.add_master(user1)
diff --git a/spec/finders/members_finder_spec.rb b/spec/finders/members_finder_spec.rb
index cf691cf684b..300ba8422e8 100644
--- a/spec/finders/members_finder_spec.rb
+++ b/spec/finders/members_finder_spec.rb
@@ -9,7 +9,7 @@ describe MembersFinder, '#execute' do
   let(:user3)        { create(:user) }
   let(:user4)        { create(:user) }
 
-  it 'returns members for project and parent groups' do
+  it 'returns members for project and parent groups', :nested_groups do
     nested_group.request_access(user1)
     member1 = group.add_master(user2)
     member2 = nested_group.add_master(user3)
diff --git a/spec/lib/gitlab/cache/ci/project_pipeline_status_spec.rb b/spec/lib/gitlab/cache/ci/project_pipeline_status_spec.rb
index b386852b196..cfb5cba054e 100644
--- a/spec/lib/gitlab/cache/ci/project_pipeline_status_spec.rb
+++ b/spec/lib/gitlab/cache/ci/project_pipeline_status_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Gitlab::Cache::Ci::ProjectPipelineStatus, :redis do
-  let(:project) { create(:project) }
+  let!(:project) { create(:project) }
   let(:pipeline_status) { described_class.new(project) }
   let(:cache_key) { "projects/#{project.id}/pipeline_status" }
 
@@ -18,7 +18,7 @@ describe Gitlab::Cache::Ci::ProjectPipelineStatus, :redis do
     let(:sha) { '424d1b73bc0d3cb726eb7dc4ce17a4d48552f8c6' }
     let(:ref) { 'master' }
     let(:pipeline_info) { { sha: sha, status: status, ref: ref } }
-    let(:project_without_status) { create(:project) }
+    let!(:project_without_status) { create(:project) }
 
     describe '.load_in_batch_for_projects' do
       it 'preloads pipeline_status on projects' do
diff --git a/spec/lib/gitlab/group_hierarchy_spec.rb b/spec/lib/gitlab/group_hierarchy_spec.rb
new file mode 100644
index 00000000000..5d0ed1522b3
--- /dev/null
+++ b/spec/lib/gitlab/group_hierarchy_spec.rb
@@ -0,0 +1,53 @@
+require 'spec_helper'
+
+describe Gitlab::GroupHierarchy, :postgresql do
+  let!(:parent) { create(:group) }
+  let!(:child1) { create(:group, parent: parent) }
+  let!(:child2) { create(:group, parent: child1) }
+
+  describe '#base_and_ancestors' do
+    let(:relation) do
+      described_class.new(Group.where(id: child2.id)).base_and_ancestors
+    end
+
+    it 'includes the base rows' do
+      expect(relation).to include(child2)
+    end
+
+    it 'includes all of the ancestors' do
+      expect(relation).to include(parent, child1)
+    end
+  end
+
+  describe '#base_and_descendants' do
+    let(:relation) do
+      described_class.new(Group.where(id: parent.id)).base_and_descendants
+    end
+
+    it 'includes the base rows' do
+      expect(relation).to include(parent)
+    end
+
+    it 'includes all the descendants' do
+      expect(relation).to include(child1, child2)
+    end
+  end
+
+  describe '#all_groups' do
+    let(:relation) do
+      described_class.new(Group.where(id: child1.id)).all_groups
+    end
+
+    it 'includes the base rows' do
+      expect(relation).to include(child1)
+    end
+
+    it 'includes the ancestors' do
+      expect(relation).to include(parent)
+    end
+
+    it 'includes the descendants' do
+      expect(relation).to include(child2)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/import_export/members_mapper_spec.rb b/spec/lib/gitlab/import_export/members_mapper_spec.rb
index b9d4e59e770..3e0291c9ae9 100644
--- a/spec/lib/gitlab/import_export/members_mapper_spec.rb
+++ b/spec/lib/gitlab/import_export/members_mapper_spec.rb
@@ -2,9 +2,9 @@ require 'spec_helper'
 
 describe Gitlab::ImportExport::MembersMapper, services: true do
   describe 'map members' do
-    let(:user) { create(:admin, authorized_projects_populated: true) }
+    let(:user) { create(:admin) }
     let(:project) { create(:empty_project, :public, name: 'searchable_project') }
-    let(:user2) { create(:user, authorized_projects_populated: true) }
+    let(:user2) { create(:user) }
     let(:exported_user_id) { 99 }
     let(:exported_members) do
       [{
@@ -74,7 +74,7 @@ describe Gitlab::ImportExport::MembersMapper, services: true do
     end
 
     context 'user is not an admin' do
-      let(:user) { create(:user, authorized_projects_populated: true) }
+      let(:user) { create(:user) }
 
       it 'does not map a project member' do
         expect(members_mapper.map[exported_user_id]).to eq(user.id)
@@ -94,7 +94,7 @@ describe Gitlab::ImportExport::MembersMapper, services: true do
     end
 
     context 'importer same as group member' do
-      let(:user2) { create(:admin, authorized_projects_populated: true) }
+      let(:user2) { create(:admin) }
       let(:group) { create(:group) }
       let(:project) { create(:empty_project, :public, name: 'searchable_project', namespace: group) }
       let(:members_mapper) do
diff --git a/spec/lib/gitlab/project_authorizations_spec.rb b/spec/lib/gitlab/project_authorizations_spec.rb
new file mode 100644
index 00000000000..67321f43710
--- /dev/null
+++ b/spec/lib/gitlab/project_authorizations_spec.rb
@@ -0,0 +1,73 @@
+require 'spec_helper'
+
+describe Gitlab::ProjectAuthorizations do
+  let(:group) { create(:group) }
+  let!(:owned_project) { create(:empty_project) }
+  let!(:other_project) { create(:empty_project) }
+  let!(:group_project) { create(:empty_project, namespace: group) }
+
+  let(:user) { owned_project.namespace.owner }
+
+  def map_access_levels(rows)
+    rows.each_with_object({}) do |row, hash|
+      hash[row.project_id] = row.access_level
+    end
+  end
+
+  before do
+    other_project.team << [user, :reporter]
+    group.add_developer(user)
+  end
+
+  let(:authorizations) do
+    klass = if Group.supports_nested_groups?
+              Gitlab::ProjectAuthorizations::WithNestedGroups
+            else
+              Gitlab::ProjectAuthorizations::WithoutNestedGroups
+            end
+
+    klass.new(user).calculate
+  end
+
+  it 'returns the correct number of authorizations' do
+    expect(authorizations.length).to eq(3)
+  end
+
+  it 'includes the correct projects' do
+    expect(authorizations.pluck(:project_id)).
+      to include(owned_project.id, other_project.id, group_project.id)
+  end
+
+  it 'includes the correct access levels' do
+    mapping = map_access_levels(authorizations)
+
+    expect(mapping[owned_project.id]).to eq(Gitlab::Access::MASTER)
+    expect(mapping[other_project.id]).to eq(Gitlab::Access::REPORTER)
+    expect(mapping[group_project.id]).to eq(Gitlab::Access::DEVELOPER)
+  end
+
+  if Group.supports_nested_groups?
+    context 'with nested groups' do
+      let!(:nested_group) { create(:group, parent: group) }
+      let!(:nested_project) { create(:empty_project, namespace: nested_group) }
+
+      it 'includes nested groups' do
+        expect(authorizations.pluck(:project_id)).to include(nested_project.id)
+      end
+
+      it 'inherits access levels when the user is not a member of a nested group' do
+        mapping = map_access_levels(authorizations)
+
+        expect(mapping[nested_project.id]).to eq(Gitlab::Access::DEVELOPER)
+      end
+
+      it 'uses the greatest access level when a user is a member of a nested group' do
+        nested_group.add_master(user)
+
+        mapping = map_access_levels(authorizations)
+
+        expect(mapping[nested_project.id]).to eq(Gitlab::Access::MASTER)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/sql/recursive_cte_spec.rb b/spec/lib/gitlab/sql/recursive_cte_spec.rb
new file mode 100644
index 00000000000..25146860615
--- /dev/null
+++ b/spec/lib/gitlab/sql/recursive_cte_spec.rb
@@ -0,0 +1,49 @@
+require 'spec_helper'
+
+describe Gitlab::SQL::RecursiveCTE, :postgresql do
+  let(:cte) { described_class.new(:cte_name) }
+
+  describe '#to_arel' do
+    it 'generates an Arel relation for the CTE body' do
+      rel1 = User.where(id: 1)
+      rel2 = User.where(id: 2)
+
+      cte << rel1
+      cte << rel2
+
+      sql = cte.to_arel.to_sql
+      name = ActiveRecord::Base.connection.quote_table_name(:cte_name)
+
+      sql1, sql2 = ActiveRecord::Base.connection.unprepared_statement do
+        [rel1.except(:order).to_sql, rel2.except(:order).to_sql]
+      end
+
+      expect(sql).to eq("#{name} AS (#{sql1}\nUNION\n#{sql2})")
+    end
+  end
+
+  describe '#alias_to' do
+    it 'returns an alias for the CTE' do
+      table = Arel::Table.new(:kittens)
+
+      source_name = ActiveRecord::Base.connection.quote_table_name(:cte_name)
+      alias_name = ActiveRecord::Base.connection.quote_table_name(:kittens)
+
+      expect(cte.alias_to(table).to_sql).to eq("#{source_name} AS #{alias_name}")
+    end
+  end
+
+  describe '#apply_to' do
+    it 'applies a CTE to an ActiveRecord::Relation' do
+      user = create(:user)
+      cte = described_class.new(:cte_name)
+
+      cte << User.where(id: user.id)
+
+      relation = cte.apply_to(User.all)
+
+      expect(relation.to_sql).to match(/WITH RECURSIVE.+cte_name/)
+      expect(relation.to_a).to eq(User.where(id: user.id).to_a)
+    end
+  end
+end
diff --git a/spec/migrations/fill_authorized_projects_spec.rb b/spec/migrations/fill_authorized_projects_spec.rb
deleted file mode 100644
index 99dc4195818..00000000000
--- a/spec/migrations/fill_authorized_projects_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require 'spec_helper'
-require Rails.root.join('db', 'post_migrate', '20170106142508_fill_authorized_projects.rb')
-
-describe FillAuthorizedProjects do
-  describe '#up' do
-    it 'schedules the jobs in batches' do
-      user1 = create(:user)
-      user2 = create(:user)
-
-      expect(Sidekiq::Client).to receive(:push_bulk).with(
-        'class' => 'AuthorizedProjectsWorker',
-        'args'  => [[user1.id], [user2.id]]
-      )
-
-      described_class.new.up
-    end
-  end
-end
diff --git a/spec/models/concerns/routable_spec.rb b/spec/models/concerns/routable_spec.rb
index 49a4132f763..0e10d91836d 100644
--- a/spec/models/concerns/routable_spec.rb
+++ b/spec/models/concerns/routable_spec.rb
@@ -115,123 +115,6 @@ describe Group, 'Routable' do
     end
   end
 
-  describe '.member_descendants' do
-    let!(:user) { create(:user) }
-    let!(:nested_group) { create(:group, parent: group) }
-
-    before { group.add_owner(user) }
-    subject { described_class.member_descendants(user.id) }
-
-    it { is_expected.to eq([nested_group]) }
-  end
-
-  describe '.member_self_and_descendants' do
-    let!(:user) { create(:user) }
-    let!(:nested_group) { create(:group, parent: group) }
-
-    before { group.add_owner(user) }
-    subject { described_class.member_self_and_descendants(user.id) }
-
-    it { is_expected.to match_array [group, nested_group] }
-  end
-
-  describe '.member_hierarchy' do
-    # foo/bar would also match foo/barbaz instead of just foo/bar and foo/bar/baz
-    let!(:user) { create(:user) }
-
-    #                group
-    #        _______ (foo) _______
-    #       |                     |
-    #       |                     |
-    # nested_group_1        nested_group_2
-    # (bar)                 (barbaz)
-    #       |                     |
-    #       |                     |
-    # nested_group_1_1      nested_group_2_1
-    # (baz)                 (baz)
-    #
-    let!(:nested_group_1) { create :group, parent: group, name: 'bar' }
-    let!(:nested_group_1_1) { create :group, parent: nested_group_1, name: 'baz' }
-    let!(:nested_group_2) { create :group, parent: group, name: 'barbaz' }
-    let!(:nested_group_2_1) { create :group, parent: nested_group_2, name: 'baz' }
-
-    context 'user is not a member of any group' do
-      subject { described_class.member_hierarchy(user.id) }
-
-      it 'returns an empty array' do
-        is_expected.to eq []
-      end
-    end
-
-    context 'user is member of all groups' do
-      before do
-        group.add_owner(user)
-        nested_group_1.add_owner(user)
-        nested_group_1_1.add_owner(user)
-        nested_group_2.add_owner(user)
-        nested_group_2_1.add_owner(user)
-      end
-      subject { described_class.member_hierarchy(user.id) }
-
-      it 'returns all groups' do
-        is_expected.to match_array [
-          group,
-          nested_group_1, nested_group_1_1,
-          nested_group_2, nested_group_2_1
-        ]
-      end
-    end
-
-    context 'user is member of the top group' do
-      before { group.add_owner(user) }
-      subject { described_class.member_hierarchy(user.id) }
-
-      it 'returns all groups' do
-        is_expected.to match_array [
-          group,
-          nested_group_1, nested_group_1_1,
-          nested_group_2, nested_group_2_1
-        ]
-      end
-    end
-
-    context 'user is member of the first child (internal node), branch 1' do
-      before { nested_group_1.add_owner(user) }
-      subject { described_class.member_hierarchy(user.id) }
-
-      it 'returns the groups in the hierarchy' do
-        is_expected.to match_array [
-          group,
-          nested_group_1, nested_group_1_1
-        ]
-      end
-    end
-
-    context 'user is member of the first child (internal node), branch 2' do
-      before { nested_group_2.add_owner(user) }
-      subject { described_class.member_hierarchy(user.id) }
-
-      it 'returns the groups in the hierarchy' do
-        is_expected.to match_array [
-          group,
-          nested_group_2, nested_group_2_1
-        ]
-      end
-    end
-
-    context 'user is member of the last child (leaf node)' do
-      before { nested_group_1_1.add_owner(user) }
-      subject { described_class.member_hierarchy(user.id) }
-
-      it 'returns the groups in the hierarchy' do
-        is_expected.to match_array [
-          group,
-          nested_group_1, nested_group_1_1
-        ]
-      end
-    end
-  end
-
   describe '#full_path' do
     let(:group) { create(:group) }
     let(:nested_group) { create(:group, parent: group) }
diff --git a/spec/models/group_spec.rb b/spec/models/group_spec.rb
index 6ca1eb0374d..316bf153660 100644
--- a/spec/models/group_spec.rb
+++ b/spec/models/group_spec.rb
@@ -340,7 +340,7 @@ describe Group, models: true do
     it { expect(subject.parent).to be_kind_of(Group) }
   end
 
-  describe '#members_with_parents' do
+  describe '#members_with_parents', :nested_groups do
     let!(:group) { create(:group, :nested) }
     let!(:master) { group.parent.add_user(create(:user), GroupMember::MASTER) }
     let!(:developer) { group.add_user(create(:user), GroupMember::DEVELOPER) }
diff --git a/spec/models/members/project_member_spec.rb b/spec/models/members/project_member_spec.rb
index 87ea2e70680..cf9c701e8c5 100644
--- a/spec/models/members/project_member_spec.rb
+++ b/spec/models/members/project_member_spec.rb
@@ -22,16 +22,15 @@ describe ProjectMember, models: true do
   end
 
   describe '.add_user' do
-    context 'when called with the project owner' do
-      it 'adds the user as a member' do
-        project = create(:empty_project)
+    it 'adds the user as a member' do
+      user = create(:user)
+      project = create(:empty_project)
 
-        expect(project.users).not_to include(project.owner)
+      expect(project.users).not_to include(user)
 
-        described_class.add_user(project, project.owner, :master, current_user: project.owner)
+      described_class.add_user(project, user, :master, current_user: project.owner)
 
-        expect(project.users.reload).to include(project.owner)
-      end
+      expect(project.users.reload).to include(user)
     end
   end
 
diff --git a/spec/models/namespace_spec.rb b/spec/models/namespace_spec.rb
index 8624616316c..99abb1f896c 100644
--- a/spec/models/namespace_spec.rb
+++ b/spec/models/namespace_spec.rb
@@ -287,21 +287,21 @@ describe Namespace, models: true do
     end
   end
 
-  describe '#ancestors' do
+  describe '#ancestors', :nested_groups do
     let(:group) { create(:group) }
     let(:nested_group) { create(:group, parent: group) }
     let(:deep_nested_group) { create(:group, parent: nested_group) }
     let(:very_deep_nested_group) { create(:group, parent: deep_nested_group) }
 
     it 'returns the correct ancestors' do
-      expect(very_deep_nested_group.ancestors).to eq([group, nested_group, deep_nested_group])
-      expect(deep_nested_group.ancestors).to eq([group, nested_group])
-      expect(nested_group.ancestors).to eq([group])
+      expect(very_deep_nested_group.ancestors).to include(group, nested_group, deep_nested_group)
+      expect(deep_nested_group.ancestors).to include(group, nested_group)
+      expect(nested_group.ancestors).to include(group)
       expect(group.ancestors).to eq([])
     end
   end
 
-  describe '#descendants' do
+  describe '#descendants', :nested_groups do
     let!(:group) { create(:group, path: 'git_lab') }
     let!(:nested_group) { create(:group, parent: group) }
     let!(:deep_nested_group) { create(:group, parent: nested_group) }
@@ -311,9 +311,9 @@ describe Namespace, models: true do
 
     it 'returns the correct descendants' do
       expect(very_deep_nested_group.descendants.to_a).to eq([])
-      expect(deep_nested_group.descendants.to_a).to eq([very_deep_nested_group])
-      expect(nested_group.descendants.to_a).to eq([deep_nested_group, very_deep_nested_group])
-      expect(group.descendants.to_a).to eq([nested_group, deep_nested_group, very_deep_nested_group])
+      expect(deep_nested_group.descendants.to_a).to include(very_deep_nested_group)
+      expect(nested_group.descendants.to_a).to include(deep_nested_group, very_deep_nested_group)
+      expect(group.descendants.to_a).to include(nested_group, deep_nested_group, very_deep_nested_group)
     end
   end
 
diff --git a/spec/models/project_group_link_spec.rb b/spec/models/project_group_link_spec.rb
index 9b711bfc007..4161b9158b1 100644
--- a/spec/models/project_group_link_spec.rb
+++ b/spec/models/project_group_link_spec.rb
@@ -23,7 +23,7 @@ describe ProjectGroupLink do
       expect(project_group_link).not_to be_valid
     end
 
-    it "doesn't allow a project to be shared with an ancestor of the group it is in" do
+    it "doesn't allow a project to be shared with an ancestor of the group it is in", :nested_groups do
       project_group_link.group = parent_group
 
       expect(project_group_link).not_to be_valid
diff --git a/spec/models/project_team_spec.rb b/spec/models/project_team_spec.rb
index 942eeab251d..fb2d5f60009 100644
--- a/spec/models/project_team_spec.rb
+++ b/spec/models/project_team_spec.rb
@@ -81,7 +81,7 @@ describe ProjectTeam, models: true do
         user = create(:user)
         project.add_guest(user)
 
-        expect(project.team.members).to contain_exactly(user)
+        expect(project.team.members).to contain_exactly(user, project.owner)
       end
 
       it 'returns project members of a specified level' do
@@ -100,7 +100,8 @@ describe ProjectTeam, models: true do
           group_access: Gitlab::Access::GUEST
         )
 
-        expect(project.team.members).to contain_exactly(group_member.user)
+        expect(project.team.members).
+          to contain_exactly(group_member.user, project.owner)
       end
 
       it 'returns invited members of a group of a specified level' do
@@ -137,7 +138,10 @@ describe ProjectTeam, models: true do
 
   describe '#find_member' do
     context 'personal project' do
-      let(:project) { create(:empty_project, :public, :access_requestable) }
+      let(:project) do
+        create(:empty_project, :public, :access_requestable)
+      end
+
       let(:requester) { create(:user) }
 
       before do
@@ -200,7 +204,9 @@ describe ProjectTeam, models: true do
     let(:requester) { create(:user) }
 
     context 'personal project' do
-      let(:project) { create(:empty_project, :public, :access_requestable) }
+      let(:project) do
+        create(:empty_project, :public, :access_requestable)
+      end
 
       context 'when project is not shared with group' do
         before do
@@ -244,7 +250,9 @@ describe ProjectTeam, models: true do
 
     context 'group project' do
       let(:group) { create(:group, :access_requestable) }
-      let!(:project) { create(:empty_project, group: group) }
+      let!(:project) do
+        create(:empty_project, group: group)
+      end
 
       before do
         group.add_master(master)
@@ -265,8 +273,15 @@ describe ProjectTeam, models: true do
     let(:group) { create(:group) }
     let(:developer) { create(:user) }
     let(:master) { create(:user) }
-    let(:personal_project) { create(:empty_project, namespace: developer.namespace) }
-    let(:group_project) { create(:empty_project, namespace: group) }
+
+    let(:personal_project) do
+      create(:empty_project, namespace: developer.namespace)
+    end
+
+    let(:group_project) do
+      create(:empty_project, namespace: group)
+    end
+
     let(:members_project) { create(:empty_project) }
     let(:shared_project) { create(:empty_project) }
 
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index f2c059010f4..e880651b091 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -611,16 +611,6 @@ describe User, models: true do
     it { expect(User.without_projects).to include user_without_project2 }
   end
 
-  describe '.not_in_project' do
-    before do
-      User.delete_all
-      @user = create :user
-      @project = create(:empty_project)
-    end
-
-    it { expect(User.not_in_project(@project)).to include(@user, @project.owner) }
-  end
-
   describe 'user creation' do
     describe 'normal user' do
       let(:user) { create(:user, name: 'John Smith') }
@@ -1535,48 +1525,103 @@ describe User, models: true do
     end
   end
 
-  describe '#nested_groups' do
+  describe '#all_expanded_groups' do
+    # foo/bar would also match foo/barbaz instead of just foo/bar and foo/bar/baz
     let!(:user) { create(:user) }
-    let!(:group) { create(:group) }
-    let!(:nested_group) { create(:group, parent: group) }
 
-    before do
-      group.add_owner(user)
+    #                group
+    #        _______ (foo) _______
+    #       |                     |
+    #       |                     |
+    # nested_group_1        nested_group_2
+    # (bar)                 (barbaz)
+    #       |                     |
+    #       |                     |
+    # nested_group_1_1      nested_group_2_1
+    # (baz)                 (baz)
+    #
+    let!(:group) { create :group }
+    let!(:nested_group_1) { create :group, parent: group, name: 'bar' }
+    let!(:nested_group_1_1) { create :group, parent: nested_group_1, name: 'baz' }
+    let!(:nested_group_2) { create :group, parent: group, name: 'barbaz' }
+    let!(:nested_group_2_1) { create :group, parent: nested_group_2, name: 'baz' }
 
-      # Add more data to ensure method does not include wrong groups
-      create(:group).add_owner(create(:user))
+    subject { user.all_expanded_groups }
+
+    context 'user is not a member of any group' do
+      it 'returns an empty array' do
+        is_expected.to eq([])
+      end
     end
 
-    it { expect(user.nested_groups).to eq([nested_group]) }
-  end
+    context 'user is member of all groups' do
+      before do
+        group.add_owner(user)
+        nested_group_1.add_owner(user)
+        nested_group_1_1.add_owner(user)
+        nested_group_2.add_owner(user)
+        nested_group_2_1.add_owner(user)
+      end
 
-  describe '#all_expanded_groups' do
-    let!(:user) { create(:user) }
-    let!(:group) { create(:group) }
-    let!(:nested_group_1) { create(:group, parent: group) }
-    let!(:nested_group_2) { create(:group, parent: group) }
+      it 'returns all groups' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1,
+          nested_group_2, nested_group_2_1
+        ]
+      end
+    end
 
-    before { nested_group_1.add_owner(user) }
+    context 'user is member of the top group' do
+      before { group.add_owner(user) }
 
-    it { expect(user.all_expanded_groups).to match_array [group, nested_group_1] }
-  end
+      if Group.supports_nested_groups?
+        it 'returns all groups' do
+          is_expected.to match_array [
+            group,
+            nested_group_1, nested_group_1_1,
+            nested_group_2, nested_group_2_1
+          ]
+        end
+      else
+        it 'returns the top-level groups' do
+          is_expected.to match_array [group]
+        end
+      end
+    end
 
-  describe '#nested_groups_projects' do
-    let!(:user) { create(:user) }
-    let!(:group) { create(:group) }
-    let!(:nested_group) { create(:group, parent: group) }
-    let!(:project) { create(:empty_project, namespace: group) }
-    let!(:nested_project) { create(:empty_project, namespace: nested_group) }
+    context 'user is member of the first child (internal node), branch 1', :nested_groups do
+      before { nested_group_1.add_owner(user) }
 
-    before do
-      group.add_owner(user)
+      it 'returns the groups in the hierarchy' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1
+        ]
+      end
+    end
+
+    context 'user is member of the first child (internal node), branch 2', :nested_groups do
+      before { nested_group_2.add_owner(user) }
 
-      # Add more data to ensure method does not include wrong projects
-      other_project = create(:empty_project, namespace: create(:group, :nested))
-      other_project.add_developer(create(:user))
+      it 'returns the groups in the hierarchy' do
+        is_expected.to match_array [
+          group,
+          nested_group_2, nested_group_2_1
+        ]
+      end
     end
 
-    it { expect(user.nested_groups_projects).to eq([nested_project]) }
+    context 'user is member of the last child (leaf node)', :nested_groups do
+      before { nested_group_1_1.add_owner(user) }
+
+      it 'returns the groups in the hierarchy' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1
+        ]
+      end
+    end
   end
 
   describe '#refresh_authorized_projects', redis: true do
@@ -1596,10 +1641,6 @@ describe User, models: true do
       expect(user.project_authorizations.count).to eq(2)
     end
 
-    it 'sets the authorized_projects_populated column' do
-      expect(user.authorized_projects_populated).to eq(true)
-    end
-
     it 'stores the correct access levels' do
       expect(user.project_authorizations.where(access_level: Gitlab::Access::GUEST).exists?).to eq(true)
       expect(user.project_authorizations.where(access_level: Gitlab::Access::REPORTER).exists?).to eq(true)
@@ -1709,7 +1750,7 @@ describe User, models: true do
       end
     end
 
-    context 'with 2FA requirement on nested parent group' do
+    context 'with 2FA requirement on nested parent group', :nested_groups do
       let!(:group1) { create :group, require_two_factor_authentication: true }
       let!(:group1a) { create :group, require_two_factor_authentication: false, parent: group1 }
 
@@ -1724,7 +1765,7 @@ describe User, models: true do
       end
     end
 
-    context 'with 2FA requirement on nested child group' do
+    context 'with 2FA requirement on nested child group', :nested_groups do
       let!(:group1) { create :group, require_two_factor_authentication: false }
       let!(:group1a) { create :group, require_two_factor_authentication: true, parent: group1 }
 
diff --git a/spec/policies/group_policy_spec.rb b/spec/policies/group_policy_spec.rb
index 2077c14ff7a..4c37a553227 100644
--- a/spec/policies/group_policy_spec.rb
+++ b/spec/policies/group_policy_spec.rb
@@ -107,7 +107,7 @@ describe GroupPolicy, models: true do
     end
   end
 
-  describe 'private nested group inherit permissions' do
+  describe 'private nested group inherit permissions', :nested_groups do
     let(:nested_group) { create(:group, :private, parent: group) }
 
     subject { described_class.abilities(current_user, nested_group).to_set }
diff --git a/spec/requests/api/commits_spec.rb b/spec/requests/api/commits_spec.rb
index 0b0e4c2b112..b84361d3abd 100644
--- a/spec/requests/api/commits_spec.rb
+++ b/spec/requests/api/commits_spec.rb
@@ -5,7 +5,6 @@ describe API::Commits do
   let(:user) { create(:user) }
   let(:user2) { create(:user) }
   let!(:project) { create(:project, :repository, creator: user, namespace: user.namespace) }
-  let!(:master) { create(:project_member, :master, user: user, project: project) }
   let!(:guest) { create(:project_member, :guest, user: user2, project: project) }
   let!(:note) { create(:note_on_commit, author: user, project: project, commit_id: project.repository.commit.id, note: 'a comment on a commit') }
   let!(:another_note) { create(:note_on_commit, author: user, project: project, commit_id: project.repository.commit.id, note: 'another comment on a commit') }
diff --git a/spec/requests/api/groups_spec.rb b/spec/requests/api/groups_spec.rb
index 90b36374ded..bb53796cbd7 100644
--- a/spec/requests/api/groups_spec.rb
+++ b/spec/requests/api/groups_spec.rb
@@ -429,7 +429,7 @@ describe API::Groups do
         expect(json_response["request_access_enabled"]).to eq(group[:request_access_enabled])
       end
 
-      it "creates a nested group" do
+      it "creates a nested group", :nested_groups do
         parent = create(:group)
         parent.add_owner(user3)
         group = attributes_for(:group, { parent_id: parent.id })
diff --git a/spec/requests/api/projects_spec.rb b/spec/requests/api/projects_spec.rb
index d5c3b5b34ad..f95a287a184 100644
--- a/spec/requests/api/projects_spec.rb
+++ b/spec/requests/api/projects_spec.rb
@@ -11,8 +11,7 @@ describe API::Projects do
   let(:project) { create(:empty_project, creator_id: user.id, namespace: user.namespace) }
   let(:project2) { create(:empty_project, path: 'project2', creator_id: user.id, namespace: user.namespace) }
   let(:snippet) { create(:project_snippet, :public, author: user, project: project, title: 'example') }
-  let(:project_member) { create(:project_member, :master, user: user, project: project) }
-  let(:project_member2) { create(:project_member, :developer, user: user3, project: project) }
+  let(:project_member) { create(:project_member, :developer, user: user3, project: project) }
   let(:user4) { create(:user) }
   let(:project3) do
     create(:project,
@@ -27,7 +26,7 @@ describe API::Projects do
     builds_enabled: false,
     snippets_enabled: false)
   end
-  let(:project_member3) do
+  let(:project_member2) do
     create(:project_member,
     user: user4,
     project: project3,
@@ -210,7 +209,7 @@ describe API::Projects do
         let(:public_project) { create(:empty_project, :public) }
 
         before do
-          project_member2
+          project_member
           user3.update_attributes(starred_projects: [project, project2, project3, public_project])
         end
 
@@ -784,19 +783,18 @@ describe API::Projects do
   describe 'GET /projects/:id/users' do
     shared_examples_for 'project users response' do
       it 'returns the project users' do
-        member = create(:user)
-        create(:project_member, :developer, user: member, project: project)
-
         get api("/projects/#{project.id}/users", current_user)
 
+        user = project.namespace.owner
+
         expect(response).to have_http_status(200)
         expect(response).to include_pagination_headers
         expect(json_response).to be_an Array
         expect(json_response.size).to eq(1)
 
         first_user = json_response.first
-        expect(first_user['username']).to eq(member.username)
-        expect(first_user['name']).to eq(member.name)
+        expect(first_user['username']).to eq(user.username)
+        expect(first_user['name']).to eq(user.name)
         expect(first_user.keys).to contain_exactly(*%w[name username id state avatar_url web_url])
       end
     end
@@ -1091,8 +1089,8 @@ describe API::Projects do
     before { user4 }
     before { project3 }
     before { project4 }
-    before { project_member3 }
     before { project_member2 }
+    before { project_member }
 
     it 'returns 400 when nothing sent' do
       project_param = {}
@@ -1573,7 +1571,7 @@ describe API::Projects do
 
     context 'when authenticated as developer' do
       before do
-        project_member2
+        project_member
       end
 
       it 'returns forbidden error' do
diff --git a/spec/requests/api/v3/commits_spec.rb b/spec/requests/api/v3/commits_spec.rb
index c2e8c3ae6f7..386f60065ad 100644
--- a/spec/requests/api/v3/commits_spec.rb
+++ b/spec/requests/api/v3/commits_spec.rb
@@ -5,7 +5,6 @@ describe API::V3::Commits do
   let(:user) { create(:user) }
   let(:user2) { create(:user) }
   let!(:project) { create(:project, :repository, creator: user, namespace: user.namespace) }
-  let!(:master) { create(:project_member, :master, user: user, project: project) }
   let!(:guest) { create(:project_member, :guest, user: user2, project: project) }
   let!(:note) { create(:note_on_commit, author: user, project: project, commit_id: project.repository.commit.id, note: 'a comment on a commit') }
   let!(:another_note) { create(:note_on_commit, author: user, project: project, commit_id: project.repository.commit.id, note: 'another comment on a commit') }
diff --git a/spec/requests/api/v3/groups_spec.rb b/spec/requests/api/v3/groups_spec.rb
index bc261b5e07c..98e8c954909 100644
--- a/spec/requests/api/v3/groups_spec.rb
+++ b/spec/requests/api/v3/groups_spec.rb
@@ -421,7 +421,7 @@ describe API::V3::Groups do
         expect(json_response["request_access_enabled"]).to eq(group[:request_access_enabled])
       end
 
-      it "creates a nested group" do
+      it "creates a nested group", :nested_groups do
         parent = create(:group)
         parent.add_owner(user3)
         group = attributes_for(:group, { parent_id: parent.id })
diff --git a/spec/requests/api/v3/projects_spec.rb b/spec/requests/api/v3/projects_spec.rb
index dc7c3d125b1..bc591b2eb37 100644
--- a/spec/requests/api/v3/projects_spec.rb
+++ b/spec/requests/api/v3/projects_spec.rb
@@ -10,8 +10,7 @@ describe API::V3::Projects do
   let(:project) { create(:empty_project, creator_id: user.id, namespace: user.namespace) }
   let(:project2) { create(:empty_project, path: 'project2', creator_id: user.id, namespace: user.namespace) }
   let(:snippet) { create(:project_snippet, :public, author: user, project: project, title: 'example') }
-  let(:project_member) { create(:project_member, :master, user: user, project: project) }
-  let(:project_member2) { create(:project_member, :developer, user: user3, project: project) }
+  let(:project_member) { create(:project_member, :developer, user: user3, project: project) }
   let(:user4) { create(:user) }
   let(:project3) do
     create(:project,
@@ -25,7 +24,7 @@ describe API::V3::Projects do
     issues_enabled: false, wiki_enabled: false,
     snippets_enabled: false)
   end
-  let(:project_member3) do
+  let(:project_member2) do
     create(:project_member,
     user: user4,
     project: project3,
@@ -286,7 +285,7 @@ describe API::V3::Projects do
     let(:public_project) { create(:empty_project, :public) }
 
     before do
-      project_member2
+      project_member
       user3.update_attributes(starred_projects: [project, project2, project3, public_project])
     end
 
@@ -622,7 +621,6 @@ describe API::V3::Projects do
     context 'when authenticated' do
       before do
         project
-        project_member
       end
 
       it 'returns a project by id' do
@@ -814,8 +812,7 @@ describe API::V3::Projects do
   describe 'GET /projects/:id/users' do
     shared_examples_for 'project users response' do
       it 'returns the project users' do
-        member = create(:user)
-        create(:project_member, :developer, user: member, project: project)
+        member = project.owner
 
         get v3_api("/projects/#{project.id}/users", current_user)
 
@@ -1163,8 +1160,8 @@ describe API::V3::Projects do
     before { user4 }
     before { project3 }
     before { project4 }
-    before { project_member3 }
     before { project_member2 }
+    before { project_member }
 
     context 'when unauthenticated' do
       it 'returns authentication error' do
diff --git a/spec/services/projects/destroy_service_spec.rb b/spec/services/projects/destroy_service_spec.rb
index 4b8589b2736..0d6dd28e332 100644
--- a/spec/services/projects/destroy_service_spec.rb
+++ b/spec/services/projects/destroy_service_spec.rb
@@ -70,7 +70,7 @@ describe Projects::DestroyService, services: true do
         end
       end
 
-      expect(project.team.members.count).to eq 1
+      expect(project.team.members.count).to eq 2
     end
   end
 
diff --git a/spec/services/users/refresh_authorized_projects_service_spec.rb b/spec/services/users/refresh_authorized_projects_service_spec.rb
index b19374ef1a2..8c40d25e00c 100644
--- a/spec/services/users/refresh_authorized_projects_service_spec.rb
+++ b/spec/services/users/refresh_authorized_projects_service_spec.rb
@@ -1,15 +1,13 @@
 require 'spec_helper'
 
 describe Users::RefreshAuthorizedProjectsService do
-  let(:project) { create(:empty_project) }
+  # We're using let! here so that any expectations for the service class are not
+  # triggered twice.
+  let!(:project) { create(:empty_project) }
+
   let(:user) { project.namespace.owner }
   let(:service) { described_class.new(user) }
 
-  def create_authorization(project, user, access_level = Gitlab::Access::MASTER)
-    ProjectAuthorization.
-      create!(project: project, user: user, access_level: access_level)
-  end
-
   describe '#execute', :redis do
     it 'refreshes the authorizations using a lease' do
       expect_any_instance_of(Gitlab::ExclusiveLease).to receive(:try_obtain).
@@ -31,7 +29,8 @@ describe Users::RefreshAuthorizedProjectsService do
 
     it 'updates the authorized projects of the user' do
       project2 = create(:empty_project)
-      to_remove = create_authorization(project2, user)
+      to_remove = user.project_authorizations.
+        create!(project: project2, access_level: Gitlab::Access::MASTER)
 
       expect(service).to receive(:update_authorizations).
         with([to_remove.project_id], [[user.id, project.id, Gitlab::Access::MASTER]])
@@ -40,7 +39,10 @@ describe Users::RefreshAuthorizedProjectsService do
     end
 
     it 'sets the access level of a project to the highest available level' do
-      to_remove = create_authorization(project, user, Gitlab::Access::DEVELOPER)
+      user.project_authorizations.delete_all
+
+      to_remove = user.project_authorizations.
+        create!(project: project, access_level: Gitlab::Access::DEVELOPER)
 
       expect(service).to receive(:update_authorizations).
         with([to_remove.project_id], [[user.id, project.id, Gitlab::Access::MASTER]])
@@ -61,34 +63,10 @@ describe Users::RefreshAuthorizedProjectsService do
 
         service.update_authorizations([], [])
       end
-
-      context 'when the authorized projects column is not set' do
-        before do
-          user.update!(authorized_projects_populated: nil)
-        end
-
-        it 'populates the authorized projects column' do
-          service.update_authorizations([], [])
-
-          expect(user.authorized_projects_populated).to eq true
-        end
-      end
-
-      context 'when the authorized projects column is set' do
-        before do
-          user.update!(authorized_projects_populated: true)
-        end
-
-        it 'does nothing' do
-          expect(user).not_to receive(:set_authorized_projects_column)
-
-          service.update_authorizations([], [])
-        end
-      end
     end
 
     it 'removes authorizations that should be removed' do
-      authorization = create_authorization(project, user)
+      authorization = user.project_authorizations.find_by(project_id: project.id)
 
       service.update_authorizations([authorization.project_id])
 
@@ -96,6 +74,8 @@ describe Users::RefreshAuthorizedProjectsService do
     end
 
     it 'inserts authorizations that should be added' do
+      user.project_authorizations.delete_all
+
       service.update_authorizations([], [[user.id, project.id, Gitlab::Access::MASTER]])
 
       authorizations = user.project_authorizations
@@ -105,16 +85,6 @@ describe Users::RefreshAuthorizedProjectsService do
       expect(authorizations[0].project_id).to eq(project.id)
       expect(authorizations[0].access_level).to eq(Gitlab::Access::MASTER)
     end
-
-    it 'populates the authorized projects column' do
-      # make sure we start with a nil value no matter what the default in the
-      # factory may be.
-      user.update!(authorized_projects_populated: nil)
-
-      service.update_authorizations([], [[user.id, project.id, Gitlab::Access::MASTER]])
-
-      expect(user.authorized_projects_populated).to eq(true)
-    end
   end
 
   describe '#fresh_access_levels_per_project' do
@@ -163,7 +133,7 @@ describe Users::RefreshAuthorizedProjectsService do
       end
     end
 
-    context 'projects of subgroups of groups the user is a member of' do
+    context 'projects of subgroups of groups the user is a member of', :nested_groups do
       let(:group) { create(:group) }
       let(:nested_group) { create(:group, parent: group) }
       let!(:other_project) { create(:empty_project, group: nested_group) }
@@ -191,7 +161,7 @@ describe Users::RefreshAuthorizedProjectsService do
       end
     end
 
-    context 'projects shared with subgroups of groups the user is a member of' do
+    context 'projects shared with subgroups of groups the user is a member of', :nested_groups do
       let(:group) { create(:group) }
       let(:nested_group) { create(:group, parent: group) }
       let(:other_project) { create(:empty_project) }
@@ -208,8 +178,6 @@ describe Users::RefreshAuthorizedProjectsService do
   end
 
   describe '#current_authorizations_per_project' do
-    before { create_authorization(project, user) }
-
     let(:hash) { service.current_authorizations_per_project }
 
     it 'returns a Hash' do
@@ -233,13 +201,13 @@ describe Users::RefreshAuthorizedProjectsService do
   describe '#current_authorizations' do
     context 'without authorizations' do
       it 'returns an empty list' do
+        user.project_authorizations.delete_all
+
         expect(service.current_authorizations.empty?).to eq(true)
       end
     end
 
     context 'with an authorization' do
-      before { create_authorization(project, user) }
-
       let(:row) { service.current_authorizations.take }
 
       it 'returns the currently authorized projects' do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index e2d5928e5b2..8db141247c2 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -93,6 +93,14 @@ RSpec.configure do |config|
     Gitlab::Redis.with(&:flushall)
     Sidekiq.redis(&:flushall)
   end
+
+  config.around(:each, :nested_groups) do |example|
+    example.run if Gitlab::GroupHierarchy.supports_nested_groups?
+  end
+
+  config.around(:each, :postgresql) do |example|
+    example.run if Gitlab::Database.postgresql?
+  end
 end
 
 FactoryGirl::SyntaxRunner.class_eval do