Add specs when full ref is passed to protected_for

app/models/project.rb

@@ -1740,7 +1740,7 @@ class Project < ActiveRecord::Base
     return false if ref.nil?
     raise Repository::AmbiguousRefError if repository.ambiguous_ref?(ref)
 
-    resolved_ref = repository.expand_ref(ref)
+    resolved_ref = repository.expand_ref(ref) || ref
     ref_name = Gitlab::Git.ref_name(resolved_ref)
 
     if Gitlab::Git.branch_ref?(resolved_ref)

spec/models/project_spec.rb

@@ -2625,7 +2625,27 @@ describe Project do
       end
     end
 
-    context 'when ref name is a full branch ref' do
+    context 'when ref is a full ref' do
+      let(:ref) { 'refs/heads/master' }
+
+      context 'when ref is not protected' do
+        it 'returns false' do
+          is_expected.to be_falsey
+        end
+      end
+
+      context 'when ref is protected' do
+        before do
+          create(:protected_branch, name: 'master', project: project)
+        end
+
+        it 'returns true' do
+          is_expected.to be_truthy
+        end
+      end
+    end
+
+    context 'when ref name is a full tag ref' do
       let(:ref) { 'refs/tags/something' }
 
       before do