anchor.diff:      replace_boolean_with_bool.main();
       replace_colon_with_equals.main();
       replace_final_with_const.main();
  +    replace_null_with_closure.main();
       replace_return_type_future.main();
       replace_var_with_dynamic.main();
       replace_with_brackets.main();
  
positive.code: import 'remove_annotation_test.dart' as remove_annotation;
  import 'remove_await_test.dart' as remove_await;
  import 'remove_dead_code_test.dart' as remove_dead_code;
  import 'remove_empty_catch_test.dart' as remove_empty_catch;
  import 'remove_empty_constructor_body_test.dart'
      as remove_empty_constructor_body;
  
negative.code: import 'use_eq_eq_null_test.dart' as use_eq_eq_null;
  import 'use_is_not_empty_test.dart' as use_is_not_empty;
  import 'use_not_eq_null_test.dart' as use_not_eq_null;
  import 'use_rethrow_test.dart' as use_rethrow;
  
  main() {
    defineReflectiveSuite(() {
  