1 files changed, 140 insertions, 0 deletions
diff --git a/spec/services/auto_merge_service_spec.rb b/spec/services/auto_merge_service_spec.rb
new file mode 100644
index 00000000000..d0eefed3150
--- /dev/null
+++ b/spec/services/auto_merge_service_spec.rb
@@ -0,0 +1,140 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe AutoMergeService do
+  set(:project) { create(:project) }
+  set(:user) { create(:user) }
+  let(:service) { described_class.new(project, user) }
+
+  describe '.all_strategies' do
+    subject { described_class.all_strategies }
+
+    it 'returns all strategies' do
+      is_expected.to eq(AutoMergeService::STRATEGIES)
+    end
+  end
+
+  describe '#available_strategies' do
+    subject { service.available_strategies(merge_request) }
+
+    let(:merge_request) { create(:merge_request) }
+    let(:pipeline_status) { :running }
+
+    before do
+      create(:ci_pipeline, pipeline_status, ref: merge_request.source_branch,
+                                            sha: merge_request.diff_head_sha,
+                                            project: merge_request.source_project)
+
+      merge_request.update_head_pipeline
+    end
+
+    it 'returns available strategies' do
+      is_expected.to include('merge_when_pipeline_succeeds')
+    end
+
+    context 'when the head piipeline succeeded' do
+      let(:pipeline_status) { :success }
+
+      it 'returns available strategies' do
+        is_expected.to be_empty
+      end
+    end
+  end
+
+  describe '.get_service_class' do
+    subject { described_class.get_service_class(strategy) }
+
+    let(:strategy) { AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS }
+
+    it 'returns service instance' do
+      is_expected.to eq(AutoMerge::MergeWhenPipelineSucceedsService)
+    end
+
+    context 'when strategy is not present' do
+      let(:strategy) { }
+
+      it 'returns nil' do
+        is_expected.to be_nil
+      end
+    end
+  end
+
+  describe '#execute' do
+    subject { service.execute(merge_request, strategy) }
+
+    let(:merge_request) { create(:merge_request) }
+    let(:pipeline_status) { :running }
+    let(:strategy) { AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS }
+
+    before do
+      create(:ci_pipeline, pipeline_status, ref: merge_request.source_branch,
+                                            sha: merge_request.diff_head_sha,
+                                            project: merge_request.source_project)
+
+      merge_request.update_head_pipeline
+    end
+
+    it 'delegates to a relevant service instance' do
+      expect_next_instance_of(AutoMerge::MergeWhenPipelineSucceedsService) do |service|
+        expect(service).to receive(:execute).with(merge_request)
+      end
+
+      subject
+    end
+
+    context 'when the head piipeline succeeded' do
+      let(:pipeline_status) { :success }
+
+      it 'returns failed' do
+        is_expected.to eq(:failed)
+      end
+    end
+  end
+
+  describe '#process' do
+    subject { service.process(merge_request) }
+
+    let(:merge_request) { create(:merge_request, :merge_when_pipeline_succeeds) }
+
+    it 'delegates to a relevant service instance' do
+      expect_next_instance_of(AutoMerge::MergeWhenPipelineSucceedsService) do |service|
+        expect(service).to receive(:process).with(merge_request)
+      end
+
+      subject
+    end
+
+    context 'when auto merge is not enabled' do
+      let(:merge_request) { create(:merge_request) }
+
+      it 'returns nil' do
+        is_expected.to be_nil
+      end
+    end
+  end
+
+  describe '#cancel' do
+    subject { service.cancel(merge_request) }
+
+    let(:merge_request) { create(:merge_request, :merge_when_pipeline_succeeds) }
+
+    it 'delegates to a relevant service instance' do
+      expect_next_instance_of(AutoMerge::MergeWhenPipelineSucceedsService) do |service|
+        expect(service).to receive(:cancel).with(merge_request)
+      end
+
+      subject
+    end
+
+    context 'when auto merge is not enabled' do
+      let(:merge_request) { create(:merge_request) }
+
+      it 'returns error' do
+        expect(subject[:message]).to eq("Can't cancel the automatic merge")
+        expect(subject[:status]).to eq(:error)
+        expect(subject[:http_status]).to eq(406)
+      end
+    end
+  end
+end