1 files changed, 116 insertions, 0 deletions
diff --git a/spec/services/merge_requests/merge_orchestration_service_spec.rb b/spec/services/merge_requests/merge_orchestration_service_spec.rb
new file mode 100644
index 00000000000..c50f20d7703
--- /dev/null
+++ b/spec/services/merge_requests/merge_orchestration_service_spec.rb
@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe MergeRequests::MergeOrchestrationService do
+  let_it_be(:maintainer) { create(:user) }
+  let(:merge_params) { { sha: merge_request.diff_head_sha } }
+  let(:user) { maintainer }
+  let(:service) { described_class.new(project, user, merge_params) }
+
+  let!(:merge_request) do
+    create(:merge_request, source_project: project, source_branch: 'feature',
+                           target_project: project, target_branch: 'master')
+  end
+
+  shared_context 'fresh repository' do
+    let_it_be(:project) { create(:project, :repository) }
+
+    before_all do
+      project.add_maintainer(maintainer)
+    end
+  end
+
+  describe '#execute' do
+    subject { service.execute(merge_request) }
+
+    include_context 'fresh repository'
+
+    context 'when merge request is mergeable' do
+      context 'when merge request can be merged automatically' do
+        before do
+          create(:ci_pipeline, :detached_merge_request_pipeline, project: project, merge_request: merge_request)
+          merge_request.update_head_pipeline
+        end
+
+        it 'schedules auto merge' do
+          expect_next_instance_of(AutoMergeService, project, user, merge_params) do |service|
+            expect(service).to receive(:execute).with(merge_request).and_call_original
+          end
+
+          subject
+
+          expect(merge_request).to be_auto_merge_enabled
+          expect(merge_request.auto_merge_strategy).to eq(AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
+          expect(merge_request).not_to be_merged
+        end
+      end
+
+      context 'when merge request cannot be merged automatically' do
+        it 'merges immediately', :sidekiq_inline do
+          expect(merge_request)
+            .to receive(:merge_async).with(user.id, merge_params)
+            .and_call_original
+
+          subject
+
+          merge_request.reset
+          expect(merge_request).to be_merged
+          expect(merge_request).not_to be_auto_merge_enabled
+        end
+      end
+    end
+
+    context 'when merge request is not mergeable' do
+      before do
+        allow(merge_request).to receive(:mergeable_state?) { false }
+      end
+
+      it 'does nothing' do
+        subject
+
+        expect(merge_request).not_to be_auto_merge_enabled
+        expect(merge_request).not_to be_merged
+      end
+    end
+  end
+
+  describe '#can_merge?' do
+    subject { service.can_merge?(merge_request) }
+
+    include_context 'fresh repository'
+
+    context 'when merge request is mergeable' do
+      it { is_expected.to eq(true) }
+    end
+
+    context 'when merge request is not mergeable' do
+      before do
+        allow(merge_request).to receive(:mergeable_state?) { false }
+      end
+
+      it { is_expected.to eq(false) }
+    end
+  end
+
+  describe '#preferred_auto_merge_strategy' do
+    subject { service.preferred_auto_merge_strategy(merge_request) }
+
+    include_context 'fresh repository'
+
+    context 'when merge request can be merged automatically' do
+      before do
+        create(:ci_pipeline, :detached_merge_request_pipeline, project: project, merge_request: merge_request)
+        merge_request.update_head_pipeline
+      end
+
+      it 'fetches perferred auto merge strategy' do
+        is_expected.to eq(AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
+      end
+    end
+
+    context 'when merge request cannot be merged automatically' do
+      it { is_expected.to be_nil }
+    end
+  end
+end