1 files changed, 63 insertions, 0 deletions
diff --git a/spec/lib/api/helpers/merge_requests_helpers_spec.rb b/spec/lib/api/helpers/merge_requests_helpers_spec.rb
new file mode 100644
index 00000000000..1d68b7985f1
--- /dev/null
+++ b/spec/lib/api/helpers/merge_requests_helpers_spec.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe API::Helpers::MergeRequestsHelpers do
+  describe '#handle_merge_request_errors!' do
+    let(:helper) do
+      Class.new do
+        include API::Helpers::MergeRequestsHelpers
+      end.new
+    end
+
+    let(:merge_request) { double }
+
+    context 'when merge request is valid' do
+      it 'returns nil' do
+        allow(merge_request).to receive(:valid?).and_return(true)
+
+        expect(merge_request).not_to receive(:errors)
+
+        helper.handle_merge_request_errors!(merge_request)
+      end
+    end
+
+    context 'when merge request is invalid' do
+      before do
+        allow(merge_request).to receive(:valid?).and_return(false)
+        allow(helper).to receive_messages([
+          :unprocessable_entity!, :conflict!, :render_validation_error!
+        ])
+      end
+
+      API::Helpers::MergeRequestsHelpers::UNPROCESSABLE_ERROR_KEYS.each do |error_key|
+        it "responds to a #{error_key} error with unprocessable_entity" do
+          error = double
+          allow(merge_request).to receive(:errors).and_return({ error_key => error })
+
+          expect(helper).to receive(:unprocessable_entity!).with(error)
+
+          helper.handle_merge_request_errors!(merge_request)
+        end
+      end
+
+      it 'responds to a validate_branches error with conflict' do
+        error = double
+        allow(merge_request).to receive(:errors).and_return({ validate_branches: error })
+
+        expect(helper).to receive(:conflict!).with(error)
+
+        helper.handle_merge_request_errors!(merge_request)
+      end
+
+      it 'responds with bad request' do
+        error = double
+        allow(merge_request).to receive(:errors).and_return({ other_error: error })
+
+        expect(helper).to receive(:render_validation_error!).with(merge_request)
+
+        helper.handle_merge_request_errors!(merge_request)
+      end
+    end
+  end
+end