Send only defined dependencies

In APIv1 we've been sending all jobs from previous stages and
a `dependencies` list with names of jobs that user want to download
artifacts from. This was selected on Runners side.

In APIv1 we've planned to send only jobs that were defined (if any; and
all previous jobs by default). However I've missed the fact that
it was Runner who selected jobs, not GitLab. And now current version
of APIV4 sends all jobs everytime.

This commit fixes this. If user will define `dependencies` in his job,
then GitLab will send only selected jobs.

app/models/ci/build.rb

@@ -539,6 +539,21 @@ module Ci
       Gitlab::Ci::Build::Credentials::Factory.new(self).create!
     end
 
+    def dependencies
+      depended_jobs = depends_on_builds
+
+      return depended_jobs unless options[:dependencies] && !options[:dependencies].empty?
+
+      selected = []
+      depended_jobs.each do |job|
+        options[:dependencies].each do |job_name|
+          selected << job if job.name == job_name
+        end
+      end
+
+      selected
+    end
+
     private
 
     def update_artifacts_size

lib/api/entities.rb

@@ -796,7 +796,7 @@ module API
         expose :artifacts, using: Artifacts
         expose :cache, using: Cache
         expose :credentials, using: Credentials
-        expose :depends_on_builds, as: :dependencies, using: Dependency
+        expose :dependencies, using: Dependency
       end
     end
   end

spec/requests/api/runner_spec.rb

@@ -417,10 +417,39 @@ describe API::Runner do
           end
 
           context 'when project and pipeline have multiple jobs' do
-            let!(:job) { create(:ci_build_tag, pipeline: pipeline, token: 'job-token', name: 'spinach', stage: 'test', stage_idx: 0) }
-            let!(:test_job) { create(:ci_build, pipeline: pipeline, token: 'test-job-token', name: 'deploy', stage: 'deploy', stage_idx: 1) }
+            let!(:job) { create(:ci_build_tag, pipeline: pipeline, name: 'spinach', stage: 'test', stage_idx: 0) }
+            let!(:job2) { create(:ci_build_tag, pipeline: pipeline, name: 'rubocop', stage: 'test', stage_idx: 0) }
+            let!(:test_job) { create(:ci_build, pipeline: pipeline, name: 'deploy', stage: 'deploy', stage_idx: 1) }
 
-            before { job.success }
+            before do
+              job.success
+              job2.success
+            end
+
+            it 'returns dependent jobs' do
+              request_job
+
+              expect(response).to have_http_status(201)
+              expect(json_response['id']).to eq(test_job.id)
+              expect(json_response['dependencies'].count).to eq(2)
+              expect(json_response['dependencies']).to include({ 'id' => job.id, 'name' => job.name, 'token' => job.token },
+                                                               { 'id' => job2.id, 'name' => job2.name, 'token' => job2.token })
+            end
+          end
+
+          context 'when explicit dependencies are defined' do
+            let!(:job) { create(:ci_build_tag, pipeline: pipeline, name: 'spinach', stage: 'test', stage_idx: 0) }
+            let!(:job2) { create(:ci_build_tag, pipeline: pipeline, name: 'rubocop', stage: 'test', stage_idx: 0) }
+            let!(:test_job) do
+              create(:ci_build, pipeline: pipeline, token: 'test-job-token', name: 'deploy',
+                                stage: 'deploy', stage_idx: 1,
+                                options: { dependencies: [job2.name] })
+            end
+
+            before do
+              job.success
+              job2.success
+            end
 
             it 'returns dependent jobs' do
               request_job
@@ -428,7 +457,7 @@ describe API::Runner do
               expect(response).to have_http_status(201)
               expect(json_response['id']).to eq(test_job.id)
               expect(json_response['dependencies'].count).to eq(1)
-              expect(json_response['dependencies'][0]).to include('id' => job.id, 'name' => 'spinach', 'token' => job.token)
+              expect(json_response['dependencies'][0]).to include('id' => job2.id, 'name' => job2.name, 'token' => job2.token)
             end
           end