Remove membership from fork network when unlinking

app/services/projects/unlink_fork_service.rb

@@ -16,6 +16,7 @@ module Projects
       refresh_forks_count(@project.forked_from_project)
 
       @project.forked_project_link.destroy
+      @project.fork_network_member.destroy
     end
 
     def refresh_forks_count(project)

spec/services/projects/unlink_fork_service_spec.rb

 require 'spec_helper'
 
 describe Projects::UnlinkForkService do
-  subject { described_class.new(fork_project, user) }
+  include ProjectForksHelper
 
-  let(:fork_link) { create(:forked_project_link) }
-  let(:fork_project) { fork_link.forked_to_project }
+  subject { described_class.new(forked_project, user) }
+
+  let(:fork_link) { forked_project.forked_project_link }
+  let(:project) { create(:project, :public) }
+  let(:forked_project) { fork_project(project, user) }
   let(:user) { create(:user) }
 
   context 'with opened merge request on the source project' do
-    let(:merge_request) { create(:merge_request, source_project: fork_project, target_project: fork_link.forked_from_project) }
-    let(:mr_close_service) { MergeRequests::CloseService.new(fork_project, user) }
+    let(:merge_request) { create(:merge_request, source_project: forked_project, target_project: fork_link.forked_from_project) }
+    let(:mr_close_service) { MergeRequests::CloseService.new(forked_project, user) }
 
     before do
       allow(MergeRequests::CloseService).to receive(:new)
-        .with(fork_project, user)
+        .with(forked_project, user)
         .and_return(mr_close_service)
     end
 
@@ -25,13 +28,24 @@ describe Projects::UnlinkForkService do
   end
 
   it 'remove fork relation' do
-    expect(fork_project.forked_project_link).to receive(:destroy)
+    expect(forked_project.forked_project_link).to receive(:destroy)
+
+    subject.execute
+  end
+
+  it 'removes the link to the fork network' do
+    expect(forked_project.fork_network_member).to be_present
+    expect(forked_project.fork_network).to be_present
 
     subject.execute
+    forked_project.reload
+
+    expect(forked_project.fork_network_member).to be_nil
+    expect(forked_project.reload.fork_network).to be_nil
   end
 
   it 'refreshes the forks count cache of the source project' do
-    source = fork_project.forked_from_project
+    source = forked_project.forked_from_project
 
     expect(source.forks_count).to eq(1)