Support merge to ref for merge-commit and squash

Adds the ground work for writing into
the merge ref refs/merge-requests/:iid/merge the
merge result between source and target branches of
a MR, without further side-effects such as
mailing, MR updates and target branch changes.

app/services/merge_requests/merge_base_service.rb

@@ -15,7 +15,10 @@ module MergeRequests
 
     # Overridden in EE.
     def hooks_validation_error(_merge_request)
+<<<<<<< HEAD
       # No-op
+=======
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
     end
 
     def source
@@ -28,6 +31,7 @@ module MergeRequests
 
     private
 
+<<<<<<< HEAD
     # Overridden in EE.
     def error_check!
       # No-op
@@ -37,6 +41,8 @@ module MergeRequests
       raise MergeError, message
     end
 
+=======
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
     def handle_merge_error(*args)
       # No-op
     end

app/services/merge_requests/merge_to_ref_service.rb

@@ -14,11 +14,19 @@ module MergeRequests
     def execute(merge_request)
       @merge_request = merge_request
 
+<<<<<<< HEAD
       validate!
 
       commit_id = commit
 
       raise_error('Conflicts detected during merge') unless commit_id
+=======
+      error_check!
+
+      commit_id = commit
+
+      raise MergeError, 'Conflicts detected during merge' unless commit_id
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
 
       success(commit_id: commit_id)
     rescue MergeError => error
@@ -27,6 +35,7 @@ module MergeRequests
 
     private
 
+<<<<<<< HEAD
     def validate!
       authorization_check!
       error_check!
@@ -39,6 +48,11 @@ module MergeRequests
         if Feature.disabled?(:merge_to_tmp_merge_ref_path, project)
           'Feature is not enabled'
         elsif !merge_method_supported?
+=======
+    def error_check!
+      error =
+        if !merge_method_supported?
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
           "#{project.human_merge_method} to #{target_ref} is currently not supported."
         elsif !hooks_validation_pass?(merge_request)
           hooks_validation_error(merge_request)
@@ -50,6 +64,7 @@ module MergeRequests
           'No source for merge'
         end
 
+<<<<<<< HEAD
       raise_error(error) if error
     end
 
@@ -57,6 +72,9 @@ module MergeRequests
       unless Ability.allowed?(current_user, :admin_merge_request, project)
         raise_error("You are not allowed to merge to this ref")
       end
+=======
+      raise MergeError, error if error
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
     end
 
     def target_ref

spec/services/merge_requests/merge_to_ref_service_spec.rb

@@ -3,6 +3,7 @@
 require 'spec_helper'
 
 describe MergeRequests::MergeToRefService do
+<<<<<<< HEAD
   shared_examples_for 'MergeService for target ref' do
     it 'target_ref has the same state of target branch' do
       repo = merge_request.target_project.repository
@@ -19,6 +20,8 @@ describe MergeRequests::MergeToRefService do
     end
   end
 
+=======
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
   set(:user) { create(:user) }
   let(:merge_request) { create(:merge_request, :simple) }
   let(:project) { merge_request.project }
@@ -74,6 +77,7 @@ describe MergeRequests::MergeToRefService do
       process_merge_to_ref
     end
 
+<<<<<<< HEAD
     it 'returns error when feature is disabled' do
       stub_feature_flags(merge_to_tmp_merge_ref_path: false)
 
@@ -83,6 +87,8 @@ describe MergeRequests::MergeToRefService do
       expect(result[:message]).to eq('Feature is not enabled')
     end
 
+=======
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
     it 'returns an error when the failing to process the merge' do
       allow(project.repository).to receive(:merge_to_ref).and_return(nil)
 
@@ -101,6 +107,25 @@ describe MergeRequests::MergeToRefService do
         MergeRequests::MergeService.new(project, user, {})
       end
 
+<<<<<<< HEAD
+=======
+      shared_examples_for 'MergeService for target ref' do
+        it 'target_ref has the same state of target branch' do
+          repo = merge_request.target_project.repository
+
+          process_merge_to_ref
+          merge_service.execute(merge_request)
+
+          ref_commits = repo.commits(merge_request.merge_ref_path, limit: 3)
+          target_branch_commits = repo.commits(merge_request.target_branch, limit: 3)
+
+          ref_commits.zip(target_branch_commits).each do |ref_commit, target_branch_commit|
+            expect(ref_commit.parents).to eq(target_branch_commit.parents)
+          end
+        end
+      end
+
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
       context 'when merge commit' do
         it_behaves_like 'MergeService for target ref'
       end
@@ -185,6 +210,7 @@ describe MergeRequests::MergeToRefService do
 
       it { expect(todo).not_to be_done }
     end
+<<<<<<< HEAD
 
     it 'returns error when user has no authorization to admin the merge request' do
       unauthorized_user = create(:user)
@@ -197,5 +223,7 @@ describe MergeRequests::MergeToRefService do
       expect(result[:status]).to eq(:error)
       expect(result[:message]).to eq('You are not allowed to merge to this ref')
     end
+=======
+>>>>>>> 89c57ca2673... Support merge to ref for merge-commit and squash
   end
 end