Stub DetectRepositoryLanguagesWorker for all tests

It performs an expensive operation, but isn't required in
most of tests

app/models/repository.rb

@@ -456,6 +456,10 @@ class Repository
   def after_import
     expire_content_cache
+    # This call is stubbed in tests due to being an expensive operation
+    # It can be reenabled for specific tests via:
+    #
+    # allow(DetectRepositoryLanguagesWorker).to receive(:perform_async).and_call_original
     DetectRepositoryLanguagesWorker.perform_async(project.id)
   end

spec/requests/api/projects_spec.rb

@@ -5,6 +5,8 @@ shared_examples 'languages and percentages JSON response' do
   let(:expected_languages) { project.repository.languages.map { |language| language.values_at(:label, :value)}.to_h }
   before do
+    allow(DetectRepositoryLanguagesWorker).to receive(:perform_async).and_call_original
+
     allow(project.repository).to receive(:languages).and_return(
       [{ value: 66.69, label: "Ruby", color: "#701516", highlight: "#701516" },
        { value: 22.98, label: "JavaScript", color: "#f1e05a", highlight: "#f1e05a" },

spec/spec_helper.rb

@@ -148,6 +148,12 @@ RSpec.configure do |config|
       .with(:force_autodevops_on_by_default, anything)
       .and_return(false)
+    # Stub this call due to being an expensive operation
+    # It can be reenabled for specific tests via:
+    #
+    # allow(DetectRepositoryLanguagesWorker).to receive(:perform_async).and_call_original
+    allow(DetectRepositoryLanguagesWorker).to receive(:perform_async).and_return(true)
+
     Gitlab::ThreadMemoryCache.cache_backend.clear
   end

spec/support/helpers/project_forks_helper.rb

@@ -45,7 +45,7 @@ module ProjectForksHelper
       # not reset the @exists variable of this forked_project.repository
       # so we have to explicitly call this method to clear the @exists variable.
       # of the instance we're returning here.
-      forked_project.repository.after_import
+      forked_project.repository.expire_content_cache
     end
     forked_project