$class = get_class( $module );
$prefix = $module->getModulePrefix();
- if ( isset( $prefixes[$prefix] ) ) {
+ if ( $prefix !== '' && isset( $prefixes[$prefix] ) ) {
$this->fail( "Module prefix '{$prefix}' is shared between {$class} and {$prefixes[$prefix]}" );
}
$prefixes[$module->getModulePrefix()] = $class;