1 files changed, 87 insertions, 0 deletions
diff --git a/spec/services/merge_requests/merge_strategies/from_source_branch_spec.rb b/spec/services/merge_requests/merge_strategies/from_source_branch_spec.rb
new file mode 100644
index 00000000000..20277fdeec7
--- /dev/null
+++ b/spec/services/merge_requests/merge_strategies/from_source_branch_spec.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe MergeRequests::MergeStrategies::FromSourceBranch, feature_category: :code_review_workflow do
+  let_it_be(:user) { create(:user) }
+  let_it_be(:user2) { create(:user) }
+
+  let(:merge_request) { create(:merge_request, :simple, author: user2, assignees: [user2]) }
+  let(:project) { merge_request.project }
+
+  subject(:strategy) { described_class.new(merge_request, user) }
+
+  before do
+    project.add_maintainer(user)
+  end
+
+  describe '#validate!' do
+    context 'when source is missing' do
+      before do
+        allow(merge_request).to receive(:diff_head_sha).and_return(nil)
+      end
+
+      it 'raises source error when source is missing' do
+        error_message = 'No source for merge'
+
+        expect { strategy.validate! }
+          .to raise_exception(MergeRequests::MergeStrategies::StrategyError, error_message)
+      end
+    end
+
+    context 'when merge request should be rebased' do
+      before do
+        allow(merge_request).to receive(:should_be_rebased?).and_return(true)
+      end
+
+      it 'raises needs rebase error' do
+        error_message = 'Only fast-forward merge is allowed for your project. Please update your source branch'
+
+        expect { strategy.validate! }
+          .to raise_exception(MergeRequests::MergeStrategies::StrategyError, error_message)
+      end
+    end
+
+    context 'when merge request should be squashed but is not' do
+      before do
+        merge_request.target_project.project_setting.squash_always!
+        merge_request.update!(squash: false)
+      end
+
+      it 'raises squashing error' do
+        error_message = 'This project requires squashing commits when merge requests are accepted.'
+
+        expect { strategy.validate! }
+          .to raise_exception(MergeRequests::MergeStrategies::StrategyError, error_message)
+      end
+    end
+  end
+
+  describe '#execute_git_merge!' do
+    context 'when fast-forward is required' do
+      before do
+        project.merge_method = :ff
+        project.save!
+      end
+
+      it 'performs a fast-forward merge' do
+        expect(merge_request.target_project.repository).to receive(:ff_merge).and_return('1234')
+
+        strategy.execute_git_merge!
+      end
+    end
+
+    context 'when a merge commit is required' do
+      before do
+        project.merge_method = :merge
+        project.save!
+      end
+
+      it 'performs standard merge' do
+        expect(merge_request.target_project.repository).to receive(:merge).and_return('1234')
+
+        strategy.execute_git_merge!
+      end
+    end
+  end
+end