Add latest changes from gitlab-org/gitlab@master

16 files changed, 651 insertions, 1 deletions

diff --git a/app/graphql/mutations/merge_requests/set_assignees.rb b/app/graphql/mutations/merge_requests/set_assignees.rb
new file mode 100644
index 00000000000..8f0025f0a58
--- /dev/null
+++ b/app/graphql/mutations/merge_requests/set_assignees.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Mutations
+  module MergeRequests
+    class SetAssignees < Base
+      graphql_name 'MergeRequestSetAssignees'
+
+      argument :assignee_usernames,
+               [GraphQL::STRING_TYPE],
+               required: true,
+               description: <<~DESC
+                            The usernames to assign to the merge request. Replaces existing assignees by default.
+               DESC
+
+      argument :operation_mode,
+               Types::MutationOperationModeEnum,
+               required: false,
+               description: <<~DESC
+                            The operation to perform. Defaults to REPLACE.
+               DESC
+
+      def resolve(project_path:, iid:, assignee_usernames:, operation_mode: Types::MutationOperationModeEnum.enum[:replace])
+        Gitlab::QueryLimiting.whitelist('https://gitlab.com/gitlab-org/gitlab/issues/36098')
+
+        merge_request = authorized_find!(project_path: project_path, iid: iid)
+        project = merge_request.project
+
+        assignee_ids = []
+        assignee_ids += merge_request.assignees.map(&:id) if Types::MutationOperationModeEnum.enum.values_at(:remove, :append).include?(operation_mode)
+        user_ids = UsersFinder.new(current_user, username: assignee_usernames).execute.map(&:id)
+
+        if operation_mode == Types::MutationOperationModeEnum.enum[:remove]
+          assignee_ids -= user_ids
+        else
+          assignee_ids |= user_ids
+        end
+
+        ::MergeRequests::UpdateService.new(project, current_user, assignee_ids: assignee_ids)
+          .execute(merge_request)
+
+        {
+          merge_request: merge_request,
+          errors: merge_request.errors.full_messages
+        }
+      end
+    end
+  end
+end
diff --git a/app/graphql/types/mutation_operation_mode_enum.rb b/app/graphql/types/mutation_operation_mode_enum.rb
new file mode 100644
index 00000000000..90a29d2b0e5
--- /dev/null
+++ b/app/graphql/types/mutation_operation_mode_enum.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module Types
+  class MutationOperationModeEnum < BaseEnum
+    graphql_name 'MutationOperationMode'
+    description 'Different toggles for changing mutator behavior.'
+
+    # Suggested param name for the enum: `operation_mode`
+
+    value 'REPLACE', 'Performs a replace operation'
+    value 'APPEND', 'Performs an append operation'
+    value 'REMOVE', 'Performs a removal operation'
+  end
+end
diff --git a/app/graphql/types/mutation_type.rb b/app/graphql/types/mutation_type.rb
index 632e1fdc2df..56e724292d5 100644
--- a/app/graphql/types/mutation_type.rb
+++ b/app/graphql/types/mutation_type.rb
@@ -11,6 +11,7 @@ module Types
     mount_mutation Mutations::AwardEmojis::Toggle
     mount_mutation Mutations::MergeRequests::SetMilestone
     mount_mutation Mutations::MergeRequests::SetWip, calls_gitaly: true
+    mount_mutation Mutations::MergeRequests::SetAssignees
     mount_mutation Mutations::Notes::Create::Note, calls_gitaly: true
     mount_mutation Mutations::Notes::Create::DiffNote, calls_gitaly: true
     mount_mutation Mutations::Notes::Create::ImageDiffNote, calls_gitaly: true
diff --git a/app/models/milestone.rb b/app/models/milestone.rb
index 3552efbdd7b..d0be54eed02 100644
--- a/app/models/milestone.rb
+++ b/app/models/milestone.rb
@@ -60,6 +60,7 @@ class Milestone < ApplicationRecord
 
   validates :group, presence: true, unless: :project
   validates :project, presence: true, unless: :group
+  validates :title, presence: true
 
   validate :uniqueness_of_title, if: :title_changed?
   validate :milestone_type_check
diff --git a/changelogs/unreleased/12769-milestone-blank-name-causes-issues.yml b/changelogs/unreleased/12769-milestone-blank-name-causes-issues.yml
new file mode 100644
index 00000000000..44ec08e611b
--- /dev/null
+++ b/changelogs/unreleased/12769-milestone-blank-name-causes-issues.yml
@@ -0,0 +1,5 @@
+---
+title: Ensure milestone titles are never empty
+merge_request: 19985
+author:
+type: fixed
diff --git a/changelogs/unreleased/31919-graphql-MR-assignee-mutation.yml b/changelogs/unreleased/31919-graphql-MR-assignee-mutation.yml
new file mode 100644
index 00000000000..02c2e4421dc
--- /dev/null
+++ b/changelogs/unreleased/31919-graphql-MR-assignee-mutation.yml
@@ -0,0 +1,5 @@
+---
+title: Add MergeRequestSetAssignees GraphQL mutation
+merge_request: 19272
+author:
+type: added
diff --git a/db/migrate/20191112232338_ensure_no_empty_milestone_titles.rb b/db/migrate/20191112232338_ensure_no_empty_milestone_titles.rb
new file mode 100644
index 00000000000..76cb511424e
--- /dev/null
+++ b/db/migrate/20191112232338_ensure_no_empty_milestone_titles.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class EnsureNoEmptyMilestoneTitles < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    loop do
+      rows_updated = exec_update <<~SQL
+        UPDATE milestones SET title = '%BLANK' WHERE id IN (SELECT id FROM milestones WHERE title = '' LIMIT 500)
+      SQL
+      break if rows_updated < 500
+    end
+  end
+
+  def down; end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 36883130b78..72d1d957d6b 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_11_12_221821) do
+ActiveRecord::Schema.define(version: 2019_11_12_232338) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"
diff --git a/doc/api/graphql/reference/gitlab_schema.graphql b/doc/api/graphql/reference/gitlab_schema.graphql
index c75d9f236f9..2023f135550 100644
--- a/doc/api/graphql/reference/gitlab_schema.graphql
+++ b/doc/api/graphql/reference/gitlab_schema.graphql
@@ -3358,6 +3358,56 @@ type MergeRequestPermissions {
 }
 
 """
+Autogenerated input type of MergeRequestSetAssignees
+"""
+input MergeRequestSetAssigneesInput {
+  """
+  The usernames to assign to the merge request. Replaces existing assignees by default.
+  """
+  assigneeUsernames: [String!]!
+
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  The iid of the merge request to mutate
+  """
+  iid: String!
+
+  """
+  The operation to perform. Defaults to REPLACE.
+  """
+  operationMode: MutationOperationMode
+
+  """
+  The project the merge request to mutate is in
+  """
+  projectPath: ID!
+}
+
+"""
+Autogenerated return type of MergeRequestSetAssignees
+"""
+type MergeRequestSetAssigneesPayload {
+  """
+  A unique identifier for the client performing the mutation.
+  """
+  clientMutationId: String
+
+  """
+  Reasons why the mutation failed.
+  """
+  errors: [String!]!
+
+  """
+  The merge request after mutation
+  """
+  mergeRequest: MergeRequest
+}
+
+"""
 Autogenerated input type of MergeRequestSetMilestone
 """
 input MergeRequestSetMilestoneInput {
@@ -3537,6 +3587,7 @@ type Mutation {
   destroyNote(input: DestroyNoteInput!): DestroyNotePayload
   epicSetSubscription(input: EpicSetSubscriptionInput!): EpicSetSubscriptionPayload
   epicTreeReorder(input: EpicTreeReorderInput!): EpicTreeReorderPayload
+  mergeRequestSetAssignees(input: MergeRequestSetAssigneesInput!): MergeRequestSetAssigneesPayload
   mergeRequestSetMilestone(input: MergeRequestSetMilestoneInput!): MergeRequestSetMilestonePayload
   mergeRequestSetWip(input: MergeRequestSetWipInput!): MergeRequestSetWipPayload
   removeAwardEmoji(input: RemoveAwardEmojiInput!): RemoveAwardEmojiPayload
@@ -3546,6 +3597,26 @@ type Mutation {
   updateNote(input: UpdateNoteInput!): UpdateNotePayload
 }
 
+"""
+Different toggles for changing mutator behavior.
+"""
+enum MutationOperationMode {
+  """
+  Performs an append operation
+  """
+  APPEND
+
+  """
+  Performs a removal operation
+  """
+  REMOVE
+
+  """
+  Performs a replace operation
+  """
+  REPLACE
+}
+
 type Namespace {
   """
   Description of the namespace
diff --git a/doc/api/graphql/reference/gitlab_schema.json b/doc/api/graphql/reference/gitlab_schema.json
index 629c18629cf..420b20919a7 100644
--- a/doc/api/graphql/reference/gitlab_schema.json
+++ b/doc/api/graphql/reference/gitlab_schema.json
@@ -14737,6 +14737,33 @@
               "deprecationReason": null
             },
             {
+              "name": "mergeRequestSetAssignees",
+              "description": null,
+              "args": [
+                {
+                  "name": "input",
+                  "description": null,
+                  "type": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "INPUT_OBJECT",
+                      "name": "MergeRequestSetAssigneesInput",
+                      "ofType": null
+                    }
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "MergeRequestSetAssigneesPayload",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
               "name": "mergeRequestSetMilestone",
               "description": null,
               "args": [
@@ -15678,6 +15705,183 @@
         },
         {
           "kind": "OBJECT",
+          "name": "MergeRequestSetAssigneesPayload",
+          "description": "Autogenerated return type of MergeRequestSetAssignees",
+          "fields": [
+            {
+              "name": "clientMutationId",
+              "description": "A unique identifier for the client performing the mutation.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "errors",
+              "description": "Reasons why the mutation failed.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "LIST",
+                  "name": null,
+                  "ofType": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "SCALAR",
+                      "name": "String",
+                      "ofType": null
+                    }
+                  }
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "mergeRequest",
+              "description": "The merge request after mutation",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "MergeRequest",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            }
+          ],
+          "inputFields": null,
+          "interfaces": [
+
+          ],
+          "enumValues": null,
+          "possibleTypes": null
+        },
+        {
+          "kind": "INPUT_OBJECT",
+          "name": "MergeRequestSetAssigneesInput",
+          "description": "Autogenerated input type of MergeRequestSetAssignees",
+          "fields": null,
+          "inputFields": [
+            {
+              "name": "projectPath",
+              "description": "The project the merge request to mutate is in",
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "ID",
+                  "ofType": null
+                }
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "iid",
+              "description": "The iid of the merge request to mutate",
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "String",
+                  "ofType": null
+                }
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "assigneeUsernames",
+              "description": "The usernames to assign to the merge request. Replaces existing assignees by default.\n",
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "LIST",
+                  "name": null,
+                  "ofType": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "SCALAR",
+                      "name": "String",
+                      "ofType": null
+                    }
+                  }
+                }
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "operationMode",
+              "description": "The operation to perform. Defaults to REPLACE.\n",
+              "type": {
+                "kind": "ENUM",
+                "name": "MutationOperationMode",
+                "ofType": null
+              },
+              "defaultValue": null
+            },
+            {
+              "name": "clientMutationId",
+              "description": "A unique identifier for the client performing the mutation.",
+              "type": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              },
+              "defaultValue": null
+            }
+          ],
+          "interfaces": null,
+          "enumValues": null,
+          "possibleTypes": null
+        },
+        {
+          "kind": "ENUM",
+          "name": "MutationOperationMode",
+          "description": "Different toggles for changing mutator behavior.",
+          "fields": null,
+          "inputFields": null,
+          "interfaces": null,
+          "enumValues": [
+            {
+              "name": "REPLACE",
+              "description": "Performs a replace operation",
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "APPEND",
+              "description": "Performs an append operation",
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "REMOVE",
+              "description": "Performs a removal operation",
+              "isDeprecated": false,
+              "deprecationReason": null
+            }
+          ],
+          "possibleTypes": null
+        },
+        {
+          "kind": "OBJECT",
           "name": "CreateNotePayload",
           "description": "Autogenerated return type of CreateNote",
           "fields": [
diff --git a/doc/api/graphql/reference/index.md b/doc/api/graphql/reference/index.md
index 7ad698ee0b5..957ea489dac 100644
--- a/doc/api/graphql/reference/index.md
+++ b/doc/api/graphql/reference/index.md
@@ -483,6 +483,14 @@ The API can be explored interactively using the [GraphiQL IDE](../index.md#graph
 | `cherryPickOnCurrentMergeRequest` | Boolean! | Whether or not a user can perform `cherry_pick_on_current_merge_request` on this resource |
 | `revertOnCurrentMergeRequest` | Boolean! | Whether or not a user can perform `revert_on_current_merge_request` on this resource |
 
+### MergeRequestSetAssigneesPayload
+
+| Name  | Type  | Description |
+| ---   |  ---- | ----------  |
+| `clientMutationId` | String | A unique identifier for the client performing the mutation. |
+| `errors` | String! => Array | Reasons why the mutation failed. |
+| `mergeRequest` | MergeRequest | The merge request after mutation |
+
 ### MergeRequestSetMilestonePayload
 
 | Name  | Type  | Description |
diff --git a/doc/ci/img/junit_test_report_ui.png b/doc/ci/img/junit_test_report_ui.png
new file mode 100644
index 00000000000..380c6bbb89c
--- /dev/null
+++ b/doc/ci/img/junit_test_report_ui.png
diff --git a/doc/ci/junit_test_reports.md b/doc/ci/junit_test_reports.md
index bc30e007393..3a94e9725e7 100644
--- a/doc/ci/junit_test_reports.md
+++ b/doc/ci/junit_test_reports.md
@@ -178,3 +178,27 @@ Currently, the following tools might not work because their XML formats are unsu
 |Case|Tool|Issue|
 |---|---|---|
 |`<testcase>` does not have `classname` attribute|ESlint, sass-lint|<https://gitlab.com/gitlab-org/gitlab-foss/issues/50964>|
+
+## Viewing JUnit test reports on GitLab
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/24792) in GitLab 12.5.
+
+If JUnit XML files are generated and uploaded as part of a pipeline, these reports
+can be viewed inside the pipelines details page. The **Tests** tab on this page will
+display a list of test suites and cases reported from the XML file.
+
+![Test Reports Widget](img/junit_test_report_ui.png)
+
+You can view all the known test suites and click on each of these to see further
+details, including the cases that makeup the suite. Cases are ordered by status,
+with failed showing at the top, skipped next and successful cases last.
+
+### Enabling the feature
+
+This feature comes with the `:junit_pipeline_view` feature flag disabled by default.
+To enable this feature, ask a GitLab administrator with Rails console access to run the
+following command:
+
+```ruby
+Feature.enable(:junit_pipeline_view)
+```
diff --git a/spec/graphql/mutations/merge_requests/set_assignees_spec.rb b/spec/graphql/mutations/merge_requests/set_assignees_spec.rb
new file mode 100644
index 00000000000..e8da0e25b7d
--- /dev/null
+++ b/spec/graphql/mutations/merge_requests/set_assignees_spec.rb
@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Mutations::MergeRequests::SetAssignees do
+  let(:merge_request) { create(:merge_request) }
+  let(:user) { create(:user) }
+  subject(:mutation) { described_class.new(object: nil, context: { current_user: user }) }
+
+  describe '#resolve' do
+    let(:assignee) { create(:user) }
+    let(:assignee2) { create(:user) }
+    let(:assignee_usernames) { [assignee.username] }
+    let(:mutated_merge_request) { subject[:merge_request] }
+    subject { mutation.resolve(project_path: merge_request.project.full_path, iid: merge_request.iid, assignee_usernames: assignee_usernames) }
+
+    before do
+      merge_request.project.add_developer(assignee)
+      merge_request.project.add_developer(assignee2)
+    end
+
+    it 'raises an error if the resource is not accessible to the user' do
+      expect { subject }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+    end
+
+    context 'when the user can update the merge request' do
+      before do
+        merge_request.project.add_developer(user)
+      end
+
+      it 'replaces the assignee' do
+        merge_request.assignees = [assignee2]
+        merge_request.save!
+
+        expect(mutated_merge_request).to eq(merge_request)
+        expect(mutated_merge_request.assignees).to contain_exactly(assignee)
+        expect(subject[:errors]).to be_empty
+      end
+
+      it 'returns errors merge request could not be updated' do
+        # Make the merge request invalid
+        merge_request.allow_broken = true
+        merge_request.update!(source_project: nil)
+
+        expect(subject[:errors]).not_to be_empty
+      end
+
+      context 'when passing an empty assignee list' do
+        let(:assignee_usernames) { [] }
+
+        before do
+          merge_request.assignees = [assignee]
+          merge_request.save!
+        end
+
+        it 'removes all assignees' do
+          expect(mutated_merge_request).to eq(merge_request)
+          expect(mutated_merge_request.assignees).to eq([])
+          expect(subject[:errors]).to be_empty
+        end
+      end
+
+      context 'when passing "append" as true' do
+        subject { mutation.resolve(project_path: merge_request.project.full_path, iid: merge_request.iid, assignee_usernames: assignee_usernames, operation_mode: Types::MutationOperationModeEnum.enum[:append]) }
+
+        before do
+          merge_request.assignees = [assignee2]
+          merge_request.save!
+
+          # In CE, APPEND is a NOOP as you can't have multiple assignees
+          # We test multiple assignment in EE specs
+          stub_licensed_features(multiple_merge_request_assignees: false)
+        end
+
+        it 'is a NO-OP in FOSS' do
+          expect(mutated_merge_request).to eq(merge_request)
+          expect(mutated_merge_request.assignees).to contain_exactly(assignee2)
+          expect(subject[:errors]).to be_empty
+        end
+      end
+
+      context 'when passing "remove" as true' do
+        before do
+          merge_request.assignees = [assignee]
+          merge_request.save!
+        end
+
+        it 'removes named assignee' do
+          mutated_merge_request = mutation.resolve(project_path: merge_request.project.full_path, iid: merge_request.iid, assignee_usernames: assignee_usernames, operation_mode: Types::MutationOperationModeEnum.enum[:remove])[:merge_request]
+
+          expect(mutated_merge_request).to eq(merge_request)
+          expect(mutated_merge_request.assignees).to eq([])
+          expect(subject[:errors]).to be_empty
+        end
+
+        it 'does not remove unnamed assignee' do
+          mutated_merge_request = mutation.resolve(project_path: merge_request.project.full_path, iid: merge_request.iid, assignee_usernames: [assignee2.username], operation_mode: Types::MutationOperationModeEnum.enum[:remove])[:merge_request]
+
+          expect(mutated_merge_request).to eq(merge_request)
+          expect(mutated_merge_request.assignees).to contain_exactly(assignee)
+          expect(subject[:errors]).to be_empty
+        end
+      end
+    end
+  end
+end
diff --git a/spec/models/milestone_spec.rb b/spec/models/milestone_spec.rb
index 120ba67f328..45cd2768708 100644
--- a/spec/models/milestone_spec.rb
+++ b/spec/models/milestone_spec.rb
@@ -55,6 +55,17 @@ describe Milestone do
       end
     end
 
+    describe 'title' do
+      it { is_expected.to validate_presence_of(:title) }
+
+      it 'is invalid if title would be empty after sanitation' do
+        milestone = build(:milestone, project: project, title: '<img src=x onerror=prompt(1)>')
+
+        expect(milestone).not_to be_valid
+        expect(milestone.errors[:title]).to include("can't be blank")
+      end
+    end
+
     describe 'milestone_releases' do
       let(:milestone) { build(:milestone, project: project) }
 
diff --git a/spec/requests/api/graphql/mutations/merge_requests/set_assignees_spec.rb b/spec/requests/api/graphql/mutations/merge_requests/set_assignees_spec.rb
new file mode 100644
index 00000000000..8f908b7bf88
--- /dev/null
+++ b/spec/requests/api/graphql/mutations/merge_requests/set_assignees_spec.rb
@@ -0,0 +1,134 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Setting assignees of a merge request' do
+  include GraphqlHelpers
+
+  let(:current_user) { create(:user) }
+  let(:merge_request) { create(:merge_request) }
+  let(:project) { merge_request.project }
+  let(:assignee) { create(:user) }
+  let(:assignee2) { create(:user) }
+  let(:input) { { assignee_usernames: [assignee.username] } }
+  let(:expected_result) do
+    [{ 'username' => assignee.username }]
+  end
+
+  let(:mutation) do
+    variables = {
+      project_path: project.full_path,
+      iid: merge_request.iid.to_s
+    }
+    graphql_mutation(:merge_request_set_assignees, variables.merge(input),
+                     <<-QL.strip_heredoc
+                       clientMutationId
+                       errors
+                       mergeRequest {
+                         id
+                         assignees {
+                           nodes {
+                             username
+                           }
+                         }
+                       }
+    QL
+    )
+  end
+
+  def mutation_response
+    graphql_mutation_response(:merge_request_set_assignees)
+  end
+
+  def mutation_assignee_nodes
+    mutation_response['mergeRequest']['assignees']['nodes']
+  end
+
+  before do
+    project.add_developer(current_user)
+    project.add_developer(assignee)
+    project.add_developer(assignee2)
+  end
+
+  it 'returns an error if the user is not allowed to update the merge request' do
+    post_graphql_mutation(mutation, current_user: create(:user))
+
+    expect(graphql_errors).not_to be_empty
+  end
+
+  it 'does not allow members without the right permission to add assignees' do
+    user = create(:user)
+    project.add_guest(user)
+
+    post_graphql_mutation(mutation, current_user: user)
+
+    expect(graphql_errors).not_to be_empty
+  end
+
+  context 'with assignees already assigned' do
+    before do
+      merge_request.assignees = [assignee2]
+      merge_request.save!
+    end
+
+    it 'replaces the assignee' do
+      post_graphql_mutation(mutation, current_user: current_user)
+
+      expect(response).to have_gitlab_http_status(:success)
+      expect(mutation_assignee_nodes).to match_array(expected_result)
+    end
+  end
+
+  context 'when passing an empty list of assignees' do
+    let(:input) { { assignee_usernames: [] } }
+
+    before do
+      merge_request.assignees = [assignee2]
+      merge_request.save!
+    end
+
+    it 'removes assignee' do
+      post_graphql_mutation(mutation, current_user: current_user)
+
+      expect(response).to have_gitlab_http_status(:success)
+      expect(mutation_assignee_nodes).to eq([])
+    end
+  end
+
+  context 'when passing append as true' do
+    let(:input) { { assignee_usernames: [assignee2.username], operation_mode: Types::MutationOperationModeEnum.enum[:append] } }
+
+    before do
+      # In CE, APPEND is a NOOP as you can't have multiple assignees
+      # We test multiple assignment in EE specs
+      stub_licensed_features(multiple_merge_request_assignees: false)
+
+      merge_request.assignees = [assignee]
+      merge_request.save!
+    end
+
+    it 'does not replace the assignee in CE' do
+      post_graphql_mutation(mutation, current_user: current_user)
+
+      expect(response).to have_gitlab_http_status(:success)
+      expect(mutation_assignee_nodes).to match_array(expected_result)
+    end
+  end
+
+  context 'when passing remove as true' do
+    let(:input) { { assignee_usernames: [assignee.username], operation_mode: Types::MutationOperationModeEnum.enum[:remove] } }
+    let(:expected_result) { [] }
+
+    before do
+      merge_request.assignees = [assignee]
+      merge_request.save!
+    end
+
+    it 'removes the users in the list, while adding none' do
+      post_graphql_mutation(mutation, current_user: current_user)
+
+      expect(response).to have_gitlab_http_status(:success)
+      expect(mutation_assignee_nodes).to match_array(expected_result)
+    end
+  end
+end