Ensure forks count cache refresh for source project

Projects::ForksService#execute used to only refresh the
cache when marking a project as fork of another, but
didn't when just making simple fork to a new project.

This commit fixes that by ensuring a cache refresh
in any successful scenario.

app/services/projects/fork_service.rb

@@ -3,11 +3,16 @@
 module Projects
   class ForkService < BaseService
     def execute(fork_to_project = nil)
-      if fork_to_project
-        link_existing_project(fork_to_project)
-      else
-        fork_new_project
-      end
+      forked_project =
+        if fork_to_project
+          link_existing_project(fork_to_project)
+        else
+          fork_new_project
+        end
+
+      refresh_forks_count if forked_project&.saved?
+
+      forked_project
     end
 
     private
@@ -92,8 +97,7 @@ module Projects
     def link_fork_network(fork_to_project)
       return if fork_to_project.errors.any?
 
-      fork_to_project.fork_network_member.save &&
-        refresh_forks_count
+      fork_to_project.fork_network_member.save
     end
 
     def refresh_forks_count

changelogs/unreleased/osw-refresh-forks-count-cache-correctly.yml

+---
+title: Ensure forks count cache refresh for source project
+merge_request: 21771
+author:
+type: fixed

spec/services/projects/fork_service_spec.rb

@@ -6,6 +6,16 @@ describe Projects::ForkService do
   include ProjectForksHelper
   include Gitlab::ShellAdapter
 
+  shared_examples 'forks count cache refresh' do
+    it 'flushes the forks count cache of the source project', :clean_gitlab_redis_cache do
+      expect(from_project.forks_count).to be_zero
+
+      fork_project(from_project, to_user)
+
+      expect(from_project.forks_count).to eq(1)
+    end
+  end
+
   context 'when forking a new project' do
     describe 'fork by user' do
       before do
@@ -40,6 +50,11 @@ describe Projects::ForkService do
           end
         end
 
+        it_behaves_like 'forks count cache refresh' do
+          let(:from_project) { @from_project }
+          let(:to_user) { @to_user }
+        end
+
         describe "successfully creates project in the user namespace" do
           let(:to_project) { fork_project(@from_project, @to_user, namespace: @to_user.namespace) }
 
@@ -62,12 +77,9 @@ describe Projects::ForkService do
             expect(@from_project.avatar.file).to be_exists
           end
 
-          it 'flushes the forks count cache of the source project' do
-            expect(@from_project.forks_count).to be_zero
-
-            fork_project(@from_project, @to_user)
-
-            expect(@from_project.forks_count).to eq(1)
+          it_behaves_like 'forks count cache refresh' do
+            let(:from_project) { @from_project }
+            let(:to_user) { @to_user }
           end
 
           it 'creates a fork network with the new project and the root project set' do
@@ -102,6 +114,11 @@ describe Projects::ForkService do
           it 'sets the forked_from_project on the membership' do
             expect(to_project.fork_network_member.forked_from_project).to eq(from_forked_project)
           end
+
+          it_behaves_like 'forks count cache refresh' do
+            let(:from_project) { from_forked_project }
+            let(:to_user) { @to_user }
+          end
         end
       end