Support creating an MR on a fork from an issue

app/controllers/projects/issues_controller.rb

@@ -172,6 +172,7 @@ class Projects::IssuesController < Projects::ApplicationController
 
   def create_merge_request
     create_params = params.slice(:branch_name, :ref).merge(issue_iid: issue.iid)
+    create_params[:target_project_id] = params[:target_project_id] if Feature.enabled?(:create_confidential_merge_request, @project)
     result = ::MergeRequests::CreateFromIssueService.new(project, current_user, create_params).execute
 
     if result[:status] == :success

app/services/merge_requests/create_from_issue_service.rb

@@ -9,24 +9,27 @@ module MergeRequests
       @branch_name       = params[:branch_name]
       @issue_iid         = params[:issue_iid]
       @ref               = params[:ref]
+      @target_project_id = params[:target_project_id]
 
       super(project, user)
     end
 
     def execute
+      return error('Project not found') if target_project.blank?
+      return error('Not allowed to create merge request') unless can_create_merge_request?
       return error('Invalid issue iid') unless @issue_iid.present? && issue.present?
 
-      result = CreateBranchService.new(project, current_user).execute(branch_name, ref)
+      result = CreateBranchService.new(target_project, current_user).execute(branch_name, ref)
       return result if result[:status] == :error
 
       new_merge_request = create(merge_request)
 
       if new_merge_request.valid?
-        SystemNoteService.new_merge_request(issue, project, current_user, new_merge_request)
+        SystemNoteService.new_merge_request(issue, target_project, current_user, new_merge_request)
 
         success(new_merge_request)
       else
-        SystemNoteService.new_issue_branch(issue, project, current_user, branch_name)
+        SystemNoteService.new_issue_branch(issue, target_project, current_user, branch_name)
 
         error(new_merge_request.errors)
       end
@@ -34,6 +37,10 @@ module MergeRequests
 
     private
 
+    def can_create_merge_request?
+      can?(current_user, :create_merge_request_from, target_project)
+    end
+
     # rubocop: disable CodeReuse/ActiveRecord
     def issue
       @issue ||= IssuesFinder.new(current_user, project_id: project.id).find_by(iid: @issue_iid)
@@ -45,21 +52,21 @@ module MergeRequests
     end
 
     def ref
-      return @ref if project.repository.branch_exists?(@ref)
+      return @ref if target_project.repository.branch_exists?(@ref)
 
-      project.default_branch || 'master'
+      target_project.default_branch || 'master'
     end
 
     def merge_request
-      MergeRequests::BuildService.new(project, current_user, merge_request_params).execute
+      MergeRequests::BuildService.new(target_project, current_user, merge_request_params).execute
     end
 
     def merge_request_params
       {
         issue_iid: @issue_iid,
-        source_project_id: project.id,
+        source_project_id: target_project.id,
         source_branch: branch_name,
-        target_project_id: project.id,
+        target_project_id: target_project.id,
         target_branch: ref
       }
     end
@@ -67,5 +74,14 @@ module MergeRequests
     def success(merge_request)
       super().merge(merge_request: merge_request)
     end
+
+    def target_project
+      @target_project ||=
+        if @target_project_id.present?
+          project.forks.find_by_id(@target_project_id)
+        else
+          project
+        end
+    end
   end
 end

spec/services/merge_requests/create_from_issue_service_spec.rb

@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 describe MergeRequests::CreateFromIssueService do
+  include ProjectForksHelper
+
   let(:project) { create(:project, :repository) }
   let(:user) { create(:user) }
   let(:label_ids) { create_pair(:label, project: project).map(&:id) }
@@ -10,14 +12,17 @@ describe MergeRequests::CreateFromIssueService do
   let(:issue) { create(:issue, project: project, milestone_id: milestone_id) }
   let(:custom_source_branch) { 'custom-source-branch' }
 
-  subject(:service) { described_class.new(project, user, issue_iid: issue.iid) }
-  subject(:service_with_custom_source_branch) { described_class.new(project, user, issue_iid: issue.iid, branch_name: custom_source_branch) }
+  subject(:service) { described_class.new(project, user, service_params) }
+  subject(:service_with_custom_source_branch) { described_class.new(project, user, service_params.merge(branch_name: custom_source_branch)) }
 
   before do
     project.add_developer(user)
   end
 
   describe '#execute' do
+    context 'no target_project_id specified' do
+      let(:service_params) { { issue_iid: issue.iid } }
+
       it 'returns an error with invalid issue iid' do
         result = described_class.new(project, user, issue_iid: -1).execute
 
@@ -25,12 +30,6 @@ describe MergeRequests::CreateFromIssueService do
         expect(result[:message]).to eq('Invalid issue iid')
       end
 
-    it 'delegates issue search to IssuesFinder' do
-      expect_any_instance_of(IssuesFinder).to receive(:find_by).once.and_call_original
-
-      described_class.new(project, user, issue_iid: -1).execute
-    end
-
       it "inherits labels" do
         issue.assign_attributes(label_ids: label_ids)
 
@@ -70,7 +69,7 @@ describe MergeRequests::CreateFromIssueService do
       end
 
       it 'creates the new_issue_branch system note when the branch could be created but the merge_request cannot be created' do
-      project.project_feature.update!(merge_requests_access_level: ProjectFeature::DISABLED)
+        expect_any_instance_of(MergeRequest).to receive(:valid?).at_least(:once).and_return(false)
 
         expect(SystemNoteService).to receive(:new_issue_branch).with(issue, project, user, issue.to_branch_name)
 
@@ -124,7 +123,7 @@ describe MergeRequests::CreateFromIssueService do
       end
 
       context 'when ref branch is set' do
-      subject { described_class.new(project, user, issue_iid: issue.iid, ref: 'feature').execute }
+        subject { described_class.new(project, user, service_params.merge(ref: 'feature')).execute }
 
         it 'sets the merge request source branch to the new issue branch' do
           expect(subject[:merge_request].source_branch).to eq(issue.to_branch_name)
@@ -135,7 +134,7 @@ describe MergeRequests::CreateFromIssueService do
         end
 
         context 'when ref branch does not exist' do
-        subject { described_class.new(project, user, issue_iid: issue.iid, ref: 'no-such-branch').execute }
+          subject { described_class.new(project, user, service_params.merge(ref: 'no-such-branch')).execute }
 
           it 'creates a merge request' do
             expect { subject }.to change(project.merge_requests, :count).by(1)
@@ -147,4 +146,117 @@ describe MergeRequests::CreateFromIssueService do
         end
       end
     end
+
+    context 'target_project_id is specified' do
+      let(:service_params) { { issue_iid: issue.iid, target_project_id: target_project.id } }
+
+      context 'target project is not a fork of the project' do
+        let(:target_project) { create(:project, :repository) }
+
+        it 'does not create merge request' do
+          expect { service.execute }.to change(target_project.merge_requests, :count).by(0)
+        end
+      end
+
+      context 'target project is a fork of project project' do
+        let(:target_project) { fork_project(project, user, repository: true) }
+
+        it 'creates a branch based on issue title' do
+          service.execute
+
+          expect(target_project.repository.branch_exists?(issue.to_branch_name)).to be_truthy
+        end
+
+        it 'creates a branch using passed name' do
+          service_with_custom_source_branch.execute
+
+          expect(target_project.repository.branch_exists?(custom_source_branch)).to be_truthy
+        end
+
+        it 'creates the new_merge_request system note' do
+          expect(SystemNoteService).to receive(:new_merge_request).with(issue, target_project, user, instance_of(MergeRequest))
+
+          service.execute
+        end
+
+        it 'creates the new_issue_branch system note when the branch could be created but the merge_request cannot be created' do
+          expect_any_instance_of(MergeRequest).to receive(:valid?).at_least(:once).and_return(false)
+
+          expect(SystemNoteService).to receive(:new_issue_branch).with(issue, target_project, user, issue.to_branch_name)
+
+          service.execute
+        end
+
+        it 'creates a merge request' do
+          expect { service.execute }.to change(target_project.merge_requests, :count).by(1)
+        end
+
+        it 'sets the merge request title to: "WIP: $issue-branch-name' do
+          result = service.execute
+
+          expect(result[:merge_request].title).to eq("WIP: #{issue.to_branch_name.titleize.humanize}")
+        end
+
+        it 'sets the merge request author to current user' do
+          result = service.execute
+
+          expect(result[:merge_request].author).to eq(user)
+        end
+
+        it 'sets the merge request source branch to the new issue branch' do
+          result = service.execute
+
+          expect(result[:merge_request].source_branch).to eq(issue.to_branch_name)
+        end
+
+        it 'sets the merge request source branch to the passed branch name' do
+          result = service_with_custom_source_branch.execute
+
+          expect(result[:merge_request].source_branch).to eq(custom_source_branch)
+        end
+
+        it 'sets the merge request target branch to the project default branch' do
+          result = service.execute
+
+          expect(result[:merge_request].target_branch).to eq(project.default_branch)
+        end
+
+        it 'executes quick actions if the build service sets them in the description' do
+          allow(service).to receive(:merge_request).and_wrap_original do |m, *args|
+            m.call(*args).tap do |merge_request|
+              merge_request.description = "/assign #{user.to_reference}"
+            end
+          end
+
+          result = service.execute
+
+          expect(result[:merge_request].assignees).to eq([user])
+        end
+
+        context 'when ref branch is set' do
+          subject { described_class.new(project, user, service_params.merge(ref: 'feature')).execute }
+
+          it 'sets the merge request source branch to the new issue branch' do
+            expect(subject[:merge_request].source_branch).to eq(issue.to_branch_name)
+          end
+
+          it 'sets the merge request target branch to the ref branch' do
+            expect(subject[:merge_request].target_branch).to eq('feature')
+          end
+
+          context 'when ref branch does not exist' do
+            subject { described_class.new(project, user, service_params.merge(ref: 'no-such-branch')).execute }
+
+            it 'creates a merge request' do
+              expect { subject }.to change(target_project.merge_requests, :count).by(1)
+            end
+
+            it 'sets the merge request target branch to the project default branch' do
+              expect(subject[:merge_request].target_branch).to eq(target_project.default_branch)
+            end
+          end
+        end
+      end
+    end
+  end
 end