Expose a list of projects starred by the user to GraphQL API

Previously it was possible to get projects starred by user with
REST API, but it was impossible with GraphQL API.
Now starredProjects field was added to User GraphQL type.

app/graphql/resolvers/user_starred_projects_resolver.rb

+# frozen_string_literal: true
+
+module Resolvers
+  class UserStarredProjectsResolver < BaseResolver
+    type Types::ProjectType, null: true
+
+    argument :search, GraphQL::STRING_TYPE,
+              required: false,
+              description: 'Search query'
+
+    alias_method :user, :object
+
+    def resolve(**args)
+      StarredProjectsFinder.new(user, params: args, current_user: current_user).execute
+    end
+  end
+end

app/graphql/types/user_type.rb

@@ -37,6 +37,9 @@ module Types
     field :project_memberships, Types::ProjectMemberType.connection_type, null: true,
           description: 'Project memberships of the user',
           method: :project_members
+    field :starred_projects, Types::ProjectType.connection_type, null: true,
+          description: 'Projects starred by the user',
+          resolver: Resolvers::UserStarredProjectsResolver
 
     # Merge request field: MRs can be either authored or assigned:
     field :authored_merge_requests, Types::MergeRequestType.connection_type, null: true,

changelogs/unreleased/239562-graphql-add-starredprojects-to-user.yml

+---
+title: Expose a list of projects starred by the user to GraphQL API
+author: Pavel Kuznetsov
+merge_request: 41076
+type: added

doc/api/graphql/reference/gitlab_schema.graphql

@@ -17557,6 +17557,36 @@ type User {
     visibility: VisibilityScopesEnum
   ): SnippetConnection
 
+  """
+  Projects starred by the user
+  """
+  starredProjects(
+    """
+    Returns the elements in the list that come after the specified cursor.
+    """
+    after: String
+
+    """
+    Returns the elements in the list that come before the specified cursor.
+    """
+    before: String
+
+    """
+    Returns the first _n_ elements from the list.
+    """
+    first: Int
+
+    """
+    Returns the last _n_ elements from the list.
+    """
+    last: Int
+
+    """
+    Search query
+    """
+    search: String
+  ): ProjectConnection
+
   """
   State of the user
   """

doc/api/graphql/reference/gitlab_schema.json

@@ -51381,6 +51381,69 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "starredProjects",
+              "description": "Projects starred by the user",
+              "args": [
+                {
+                  "name": "search",
+                  "description": "Search query",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "after",
+                  "description": "Returns the elements in the list that come after the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "before",
+                  "description": "Returns the elements in the list that come before the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "first",
+                  "description": "Returns the first _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "last",
+                  "description": "Returns the last _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "ProjectConnection",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "state",
               "description": "State of the user",

spec/graphql/types/user_type_spec.rb

@@ -25,6 +25,7 @@ RSpec.describe GitlabSchema.types['User'] do
       assignedMergeRequests
       groupMemberships
       projectMemberships
+      starredProjects
     ]
 
     expect(described_class).to have_graphql_fields(*expected_fields)

spec/requests/api/graphql/user/starred_projects_query_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Getting starredProjects of the user' do
+  include GraphqlHelpers
+
+  let(:query) do
+    graphql_query_for(:user, user_params, user_fields)
+  end
+
+  let(:user_params) { { username: user.username } }
+
+  let_it_be(:project_a) { create(:project, :public) }
+  let_it_be(:project_b) { create(:project, :private) }
+  let_it_be(:project_c) { create(:project, :private) }
+  let_it_be(:user, reload: true) { create(:user) }
+
+  let(:user_fields) { 'starredProjects { nodes { id } }' }
+  let(:starred_projects) { graphql_data_at(:user, :starred_projects, :nodes) }
+
+  before do
+    project_b.add_reporter(user)
+    project_c.add_reporter(user)
+
+    user.toggle_star(project_a)
+    user.toggle_star(project_b)
+    user.toggle_star(project_c)
+
+    post_graphql(query)
+  end
+
+  it_behaves_like 'a working graphql query'
+
+  it 'found only public project' do
+    expect(starred_projects).to contain_exactly(
+      a_hash_including('id' => global_id_of(project_a))
+    )
+  end
+
+  context 'the current user is the user' do
+    let(:current_user) { user }
+
+    before do
+      post_graphql(query, current_user: current_user)
+    end
+
+    it 'found all projects' do
+      expect(starred_projects).to contain_exactly(
+        a_hash_including('id' => global_id_of(project_a)),
+        a_hash_including('id' => global_id_of(project_b)),
+        a_hash_including('id' => global_id_of(project_c))
+      )
+    end
+  end
+
+  context 'the current user is a member of a private project the user starred' do
+    let_it_be(:other_user) { create(:user) }
+
+    before do
+      project_b.add_reporter(other_user)
+
+      post_graphql(query, current_user: other_user)
+    end
+
+    it 'finds public and member projects' do
+      expect(starred_projects).to contain_exactly(
+        a_hash_including('id' => global_id_of(project_a)),
+        a_hash_including('id' => global_id_of(project_b))
+      )
+    end
+  end
+end