Return empty array when commit has no statuses in API

This makes API endpoint for Commit Statuses return empty array instead
of 404 when commit exists, but has no statuses.

Closes #3080

lib/api/commit_statuses.rb

@@ -18,10 +18,12 @@ module API
       # Examples:
       #   GET /projects/:id/repository/commits/:sha/statuses
       get ':id/repository/commits/:sha/statuses' do
-        authorize! :read_commit_status, user_project
-        sha = params[:sha]
-        ci_commit = user_project.ci_commit(sha)
-        not_found! 'Commit' unless ci_commit
+        authorize!(:read_commit_status, user_project)
+
+        ci_commit = user_project.ci_commit(params[:sha])
+        not_found!('Commit') unless user_project.commit(params[:sha])
+        return [] unless ci_commit
+
         statuses = ci_commit.statuses
         statuses = statuses.latest unless parse_boolean(params[:all])
         statuses = statuses.where(ref: params[:ref]) if params[:ref].present?

spec/requests/api/commit_status_spec.rb

@@ -2,15 +2,18 @@ require 'spec_helper'
 
 describe API::CommitStatus, api: true do
   include ApiHelpers
+
   let!(:project) { create(:project) }
   let(:commit) { project.repository.commit }
-  let!(:ci_commit) { project.ensure_ci_commit(commit.id) }
   let(:commit_status) { create(:commit_status, commit: ci_commit) }
   let(:guest) { create_user(ProjectMember::GUEST) }
   let(:reporter) { create_user(ProjectMember::REPORTER) }
   let(:developer) { create_user(ProjectMember::DEVELOPER) }
 
   describe "GET /projects/:id/repository/commits/:sha/statuses" do
+    context 'ci commit exists' do
+      let!(:ci_commit) { project.ensure_ci_commit(commit.id) }
+
       it_behaves_like 'a paginated resources' do
         let(:request) { get api("/projects/#{project.id}/repository/commits/#{commit.id}/statuses", reporter) }
       end
@@ -18,13 +21,29 @@ describe API::CommitStatus, api: true do
       context "reporter user" do
         let(:statuses_id) { json_response.map { |status| status['id'] } }
 
-      before do
-        @status1 = create(:commit_status, commit: ci_commit, status: 'running')
-        @status2 = create(:commit_status, commit: ci_commit, name: 'coverage', status: 'pending')
-        @status3 = create(:commit_status, commit: ci_commit, name: 'coverage', ref: 'develop', status: 'running', allow_failure: true)
-        @status4 = create(:commit_status, commit: ci_commit, name: 'coverage', status: 'success')
-        @status5 = create(:commit_status, commit: ci_commit, ref: 'develop', status: 'success')
-        @status6 = create(:commit_status, commit: ci_commit, status: 'success')
+        let!(:status1) do
+          create(:commit_status, commit: ci_commit, status: 'running')
+        end
+
+        let!(:status2) do
+          create(:commit_status, commit: ci_commit, name: 'coverage', status: 'pending')
+        end
+
+        let!(:status3) do
+          create(:commit_status, commit: ci_commit, name: 'coverage', ref: 'develop',
+                                 status: 'running', allow_failure: true)
+        end
+
+        let!(:status4) do
+          create(:commit_status, commit: ci_commit, name: 'coverage', status: 'success')
+        end
+
+        let!(:status5) do
+          create(:commit_status, commit: ci_commit, ref: 'develop', status: 'success')
+        end
+
+        let!(:status6) do
+          create(:commit_status, commit: ci_commit, status: 'success')
         end
 
         it "should return latest commit statuses" do
@@ -32,7 +51,7 @@ describe API::CommitStatus, api: true do
           expect(response.status).to eq(200)
 
           expect(json_response).to be_an Array
-        expect(statuses_id).to contain_exactly(@status3.id, @status4.id, @status5.id, @status6.id)
+          expect(statuses_id).to contain_exactly(status3.id, status4.id, status5.id, status6.id)
           json_response.sort_by!{ |status| status['id'] }
           expect(json_response.map{ |status| status['allow_failure'] }).to eq([true, false, false, false])
         end
@@ -42,7 +61,7 @@ describe API::CommitStatus, api: true do
           expect(response.status).to eq(200)
 
           expect(json_response).to be_an Array
-        expect(statuses_id).to contain_exactly(@status1.id, @status2.id, @status3.id, @status4.id, @status5.id, @status6.id)
+          expect(statuses_id).to contain_exactly(status1.id, status2.id, status3.id, status4.id, status5.id, status6.id)
         end
 
         it "should return latest commit statuses for specific ref" do
@@ -50,7 +69,7 @@ describe API::CommitStatus, api: true do
           expect(response.status).to eq(200)
 
           expect(json_response).to be_an Array
-        expect(statuses_id).to contain_exactly(@status3.id, @status5.id)
+          expect(statuses_id).to contain_exactly(status3.id, status5.id)
         end
 
         it "should return latest commit statuses for specific name" do
@@ -58,7 +77,20 @@ describe API::CommitStatus, api: true do
           expect(response.status).to eq(200)
 
           expect(json_response).to be_an Array
-        expect(statuses_id).to contain_exactly(@status3.id, @status4.id)
+          expect(statuses_id).to contain_exactly(status3.id, status4.id)
+        end
+      end
+    end
+
+    context 'ci commit does not exist' do
+      before do
+        get api("/projects/#{project.id}/repository/commits/#{commit.id}/statuses", reporter)
+      end
+
+      it 'returns empty array' do
+        expect(response.status).to eq 200
+        expect(json_response).to be_an Array
+        expect(json_response).to be_empty
       end
     end