Add list_projects endpoint to error tracking

app/controllers/projects/error_tracking_controller.rb

@@ -15,6 +15,14 @@ class Projects::ErrorTrackingController < Projects::ApplicationController
     end
   end
 
+  def list_projects
+    respond_to do |format|
+      format.json do
+        render_project_list_json
+      end
+    end
+  end
+
   private
 
   def render_index_json
@@ -32,6 +40,32 @@ class Projects::ErrorTrackingController < Projects::ApplicationController
     }
   end
 
+  def render_project_list_json
+    service = ErrorTracking::ListProjectsService.new(
+      project,
+      current_user,
+      list_projects_params
+    )
+    result = service.execute
+
+    if result[:status] == :success
+      render json: {
+        projects: serialize_projects(result[:projects])
+      }
+    else
+      return render(
+        status: result[:http_status] || :bad_request,
+        json: {
+          message: result[:message]
+        }
+      )
+    end
+  end
+
+  def list_projects_params
+    params.require(:error_tracking_setting).permit([:api_host, :token])
+  end
+
   def set_polling_interval
     Gitlab::PollingInterval.set_header(response, interval: POLLING_INTERVAL)
   end
@@ -41,4 +75,10 @@ class Projects::ErrorTrackingController < Projects::ApplicationController
       .new(project: project, user: current_user)
       .represent(errors)
   end
+
+  def serialize_projects(projects)
+    ErrorTracking::ProjectSerializer
+      .new(project: project, user: current_user)
+      .represent(projects)
+  end
 end

app/serializers/error_tracking/project_serializer.rb

@@ -2,6 +2,6 @@
 
 module ErrorTracking
   class ProjectSerializer < BaseSerializer
-    entity ProjectEntity
+    entity ErrorTracking::ProjectEntity
   end
 end

config/routes/project.rb

@@ -444,7 +444,11 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
         end
       end
 
-      resources :error_tracking, only: [:index], controller: :error_tracking
+      resources :error_tracking, only: [:index], controller: :error_tracking do
+        collection do
+          post :list_projects
+        end
+      end
 
       # Since both wiki and repository routing contains wildcard characters
       # its preferable to keep it below all other project routes

spec/controllers/projects/error_tracking_controller_spec.rb

@@ -107,8 +107,11 @@ describe Projects::ErrorTrackingController do
           let(:http_status) { :no_content }
 
           before do
-            expect(list_issues_service).to receive(:execute)
-              .and_return(status: :error, message: error_message, http_status: http_status)
+            expect(list_issues_service).to receive(:execute).and_return(
+              status: :error,
+              message: error_message,
+              http_status: http_status
+            )
           end
 
           it 'returns http_status with message' do
@@ -122,6 +125,113 @@ describe Projects::ErrorTrackingController do
     end
   end
 
+  describe 'POST #list_projects' do
+    context 'with insufficient permissions' do
+      before do
+        project.add_guest(user)
+      end
+
+      it 'returns 404' do
+        post :list_projects, params: list_projects_params
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
+    context 'with an anonymous user' do
+      before do
+        sign_out(user)
+      end
+
+      it 'redirects to sign-in page' do
+        post :list_projects, params: list_projects_params
+
+        expect(response).to have_gitlab_http_status(:unauthorized)
+      end
+    end
+
+    context 'with authorized user' do
+      let(:list_projects_service) { spy(:list_projects_service) }
+      let(:sentry_project) { build(:error_tracking_project) }
+
+      let(:permitted_params) do
+        ActionController::Parameters.new(
+          list_projects_params[:error_tracking_setting]
+        ).permit!
+      end
+
+      before do
+        allow(ErrorTracking::ListProjectsService)
+          .to receive(:new).with(project, user, permitted_params)
+          .and_return(list_projects_service)
+      end
+
+      context 'service result is successful' do
+        before do
+          expect(list_projects_service).to receive(:execute)
+            .and_return(status: :success, projects: [sentry_project])
+        end
+
+        it 'returns a list of projects' do
+          post :list_projects, params: list_projects_params
+
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(response).to match_response_schema('error_tracking/list_projects')
+          expect(json_response['projects']).to eq([sentry_project].as_json)
+        end
+      end
+
+      context 'service result is erroneous' do
+        let(:error_message) { 'error message' }
+
+        context 'without http_status' do
+          before do
+            expect(list_projects_service).to receive(:execute)
+              .and_return(status: :error, message: error_message)
+          end
+
+          it 'returns 400 with message' do
+            get :list_projects, params: list_projects_params
+
+            expect(response).to have_gitlab_http_status(:bad_request)
+            expect(json_response['message']).to eq(error_message)
+          end
+        end
+
+        context 'with explicit http_status' do
+          let(:http_status) { :no_content }
+
+          before do
+            expect(list_projects_service).to receive(:execute).and_return(
+              status: :error,
+              message: error_message,
+              http_status: http_status
+            )
+          end
+
+          it 'returns http_status with message' do
+            get :list_projects, params: list_projects_params
+
+            expect(response).to have_gitlab_http_status(http_status)
+            expect(json_response['message']).to eq(error_message)
+          end
+        end
+      end
+    end
+
+    private
+
+    def list_projects_params(opts = {})
+      project_params(
+        format: :json,
+        error_tracking_setting: {
+          api_host: 'gitlab.com',
+          token: 'token'
+        }
+      )
+    end
+  end
+
   private
 
   def project_params(opts = {})