FileBackendGroup::destroySingleton();
$fakeCallback = $this->createMock( RepoGroupTestHelper::class );
$fakeCallback->expects( $this->never() )->method( 'callback' );
FileBackendGroup::destroySingleton();
$fakeCallback = $this->createMock( RepoGroupTestHelper::class );
$fakeCallback->expects( $this->never() )->method( 'callback' );