Add specs for environments recently updated on branch

app/models/environment.rb

@@ -38,7 +38,7 @@ class Environment < ActiveRecord::Base
   end
 
   def recently_updated_on_branch?(ref)
-    ref.to_s == last_deployment.ref
+    ref.to_s == last_deployment.try(:ref)
   end
 
   def last_deployment

spec/models/environment_spec.rb

@@ -166,4 +166,25 @@ describe Environment, models: true do
       end
     end
   end
+
+  describe 'recently_updated_on_branch?' do
+    subject { environment.recently_updated_on_branch?('feature') }
+
+    context 'when last deployment to environment is the most recent one' do
+      before do
+        create(:deployment, environment: environment, ref: 'feature')
+      end
+
+      it { is_expected.to be true }
+    end
+
+    context 'when last deployment to environment is not the most recent' do
+      before do
+        create(:deployment, environment: environment, ref: 'feature')
+        create(:deployment, environment: environment, ref: 'master')
+      end
+
+      it { is_expected.to be false }
+    end
+  end
 end

spec/models/project_spec.rb

@@ -1688,6 +1688,48 @@ describe Project, models: true do
     end
   end
 
+  describe '#environments_recently_updated_on_branch' do
+    let(:project) { create(:project) }
+    let(:environment) { create(:environment, project: project) }
+
+    context 'when last deployment to environment is the most recent one' do
+      before do
+        create(:deployment, environment: environment, ref: 'feature')
+      end
+
+      it 'finds recently updated environment' do
+        expect(project.environments_recently_updated_on_branch('feature'))
+          .to contain_exactly(environment)
+      end
+    end
+
+    context 'when last deployment to environment is not the most recent' do
+      before do
+        create(:deployment, environment: environment, ref: 'feature')
+        create(:deployment, environment: environment, ref: 'master')
+      end
+
+      it 'does not find environment' do
+        expect(project.environments_recently_updated_on_branch('feature'))
+          .to be_empty
+      end
+    end
+
+    context 'when there are two environments that deploy to the same branch' do
+      let(:second_environment) { create(:environment, project: project) }
+
+      before do
+        create(:deployment, environment: environment, ref: 'feature')
+        create(:deployment, environment: second_environment, ref: 'feature')
+      end
+
+      it 'finds both environments' do
+        expect(project.environments_recently_updated_on_branch('feature'))
+          .to contain_exactly(environment, second_environment)
+      end
+    end
+  end
+
   def enable_lfs
     allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
   end