Add project topic to graphql

Add topics to project resolver to allow project filtering by topics.
So we have a feature parity with projects API.

Changelog: added
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/graphql/resolvers/projects_resolver.rb

@@ -24,6 +24,10 @@ module Resolvers
              required: false,
              description: 'Sort order of results.'
 
+    argument :topics, type: [GraphQL::STRING_TYPE],
+             required: false,
+             description: 'Filters projects by topics.'
+
     def resolve(**args)
       ProjectsFinder
         .new(current_user: current_user, params: project_finder_params(args), project_ids_relation: parse_gids(args[:ids]))
@@ -38,7 +42,8 @@ module Resolvers
         non_public: params[:membership],
         search: params[:search],
         search_namespaces: params[:search_namespaces],
-        sort: params[:sort]
+        sort: params[:sort],
+        topic: params[:topics]
       }.compact
     end
 

doc/api/graphql/reference/index.md

@@ -283,6 +283,7 @@ four standard [pagination arguments](#connection-pagination-arguments):
 | <a id="queryprojectssearch"></a>`search` | [`String`](#string) | Search query for project name, path, or description. |
 | <a id="queryprojectssearchnamespaces"></a>`searchNamespaces` | [`Boolean`](#boolean) | Include namespace in project search. |
 | <a id="queryprojectssort"></a>`sort` | [`String`](#string) | Sort order of results. |
+| <a id="queryprojectstopics"></a>`topics` | [`[String!]`](#string) | Filters projects by topics. |
 
 ### `Query.runner`
 

spec/finders/projects_finder_spec.rb

@@ -150,13 +150,33 @@ RSpec.describe ProjectsFinder do
 
       describe 'filter by topics' do
         before do
-          public_project.topic_list = 'foo'
+          public_project.topic_list = 'foo, bar'
           public_project.save!
         end
 
-        let(:params) { { topic: 'foo' } }
+        context 'single topic' do
+          let(:params) { { topic: 'foo' } }
 
-        it { is_expected.to eq([public_project]) }
+          it { is_expected.to eq([public_project]) }
+        end
+
+        context 'multiple topics' do
+          let(:params) { { topic: 'bar, foo' } }
+
+          it { is_expected.to eq([public_project]) }
+        end
+
+        context 'one topic matches, other one does not' do
+          let(:params) { { topic: 'foo, xyz' } }
+
+          it { is_expected.to eq([]) }
+        end
+
+        context 'no matching topic' do
+          let(:params) { { topic: 'xyz' } }
+
+          it { is_expected.to eq([]) }
+        end
       end
 
       describe 'filter by personal' do

spec/graphql/resolvers/projects_resolver_spec.rb

@@ -10,7 +10,7 @@ RSpec.describe Resolvers::ProjectsResolver do
 
     let_it_be(:group) { create(:group, name: 'public-group') }
     let_it_be(:private_group) { create(:group, name: 'private-group') }
-    let_it_be(:project) { create(:project, :public) }
+    let_it_be(:project) { create(:project, :public, tag_list: %w(ruby javascript)) }
     let_it_be(:other_project) { create(:project, :public) }
     let_it_be(:group_project) { create(:project, :public, group: group) }
     let_it_be(:private_project) { create(:project, :private) }
@@ -70,6 +70,14 @@ RSpec.describe Resolvers::ProjectsResolver do
             is_expected.to be_empty
           end
         end
+
+        context 'when topics filter is provided' do
+          let(:filters) { { topics: %w(ruby) } }
+
+          it 'returns matching project' do
+            is_expected.to contain_exactly(project)
+          end
+        end
       end
     end
 
@@ -138,6 +146,14 @@ RSpec.describe Resolvers::ProjectsResolver do
             is_expected.to match_array([named_project3, named_project1, named_project2])
           end
         end
+
+        context 'when topics filter is provided' do
+          let(:filters) { { topics: %w(ruby) } }
+
+          it 'returns matching project' do
+            is_expected.to contain_exactly(project)
+          end
+        end
       end
     end
   end