Add spec for mergeable_ci_state

jh/spec/models/jh/merge_request_spec.rb

@@ -7,4 +7,54 @@
     it_behaves_like "content validation with project", :merge_request, :title
     it_behaves_like "content validation with project", :merge_request, :description
   end
+
+  describe '#mergeable_ci_state?' do
+    let(:mono_central_pipeline) { build(:ci_empty_pipeline) }
+    let(:merge_request) { build(:merge_request, source_project: project) }
+    let(:project) { build(:project, :repository, only_allow_merge_if_pipeline_succeeds: true) }
+
+    context 'when monorepo is enabled' do
+      before do
+        allow(::MergeRequests::MonorepoService).to receive(:monorepo_enabled?).and_return(true)
+      end
+
+      context 'when no diff_head_pipeline is associated' do
+        before do
+          allow_any_instance_of(::MergeRequests::MonorepoService)
+            .to receive(:central_pipeline)
+            .and_return(mono_central_pipeline)
+        end
+
+        context 'and has no mono_central_pipeline associated' do
+          let(:mono_central_pipeline) { nil }
+
+          it { expect(merge_request.mergeable_ci_state?).to be_falsey }
+        end
+
+        context 'and a failed mono_central_pipeline is associated' do
+          before do
+            mono_central_pipeline.status = 'failed'
+          end
+
+          it { expect(merge_request.mergeable_ci_state?).to be_falsey }
+        end
+
+        context 'and a successful mono_central_pipeline is associated' do
+          before do
+            mono_central_pipeline.status = 'success'
+          end
+
+          it { expect(merge_request.mergeable_ci_state?).to be_truthy }
+        end
+
+        context 'and a skipped mono_central_pipeline is associated' do
+          before do
+            mono_central_pipeline.status = 'skipped'
+          end
+
+          it { expect(merge_request.mergeable_ci_state?).to be_falsey }
+        end
+      end
+    end
+  end
 end