Add spec for ff flag

spec/lib/generators/gitlab/snowplow_event_definition_generator_spec.rb

@@ -32,6 +32,15 @@ RSpec.describe Gitlab::SnowplowEventDefinitionGenerator do
       expect(::Gitlab::Config::Loader::Yaml.new(File.read(event_definition_path)).load_raw!).to eq(sample_event)
     end
 
+    it 'overwrites event definition file using the template' do
+      sample_event = ::Gitlab::Config::Loader::Yaml.new(fixture_file(File.join(sample_event_dir, 'sample_event.yml'))).load_raw!
+
+      described_class.new([], generator_options.merge('ff' => true)).invoke_all
+
+      event_definition_path = File.join(ce_temp_dir, 'groups__email_campaigns_controller_click.yml')
+      expect(::Gitlab::Config::Loader::Yaml.new(File.read(event_definition_path)).load_raw!).to eq(sample_event)
+    end
+
     it 'creates EE event definition file using the template' do
       sample_event = ::Gitlab::Config::Loader::Yaml.new(fixture_file(File.join(sample_event_dir, 'sample_event_ee.yml'))).load_raw!