Doh. I already wrote that test and I forgot.

spec/models/build_spec.rb

@@ -693,9 +693,9 @@ describe Ci::Build, models: true do
 
   describe 'Project#builds_for' do
     it 'returns builds from ref and build name' do
-      latest_build = project.builds_for(build.name, 'HEAD').latest.first
+      build_ids = project.builds_for(build.name, 'HEAD').map(&:id)
 
-      expect(latest_build.id).to eq(build.id)
+      expect(build_ids).to eq([build.id])
     end
   end
 end

spec/models/project_spec.rb

@@ -364,20 +364,6 @@ describe Project, models: true do
     end
   end
 
-  describe '#builds_for' do
-    let(:project) { create(:project) }
-    let(:pipeline) do
-      create(:ci_pipeline, project: project, sha: project.commit.sha)
-    end
-    let(:build) { create(:ci_build, pipeline: pipeline) }
-
-    it 'returns builds for a particular ref' do
-      build_ids = project.builds_for(build.name, build.sha).map(&:id)
-
-      expect(build_ids).to eq([build.id])
-    end
-  end
-
   describe :default_issues_tracker? do
     let(:project) { create(:project) }
     let(:ext_project) { create(:redmine_project) }