Anything similar to @VisibleForTesting annotation to use in Typescript or JavaScript?

There's a @VisibleForTesting annotation available in Java through the Google Guava library to indicate that the visibility of a type or member has been relaxed to make the code testable: annotation to make a private method public only for test classes . Subsequently there are also plugins which ensure that the methods which are annotated with @VisibleForTesting are actually being used only in the test classes.

I currently have a typescript interface where I have to add some methods to the interface just for testing purposes. For example:

interface ProcessorInterface {
  process(data: Readonly<Data>): Promise<Result>;

  // these 2 methods are only added here so that they are 
  // callable from the implementation while writing tests.
  processBatch(data: Readonly<Data>): Promise<Result>;
  validate(data: Readonly<Data>): Promise<Error[]>;
}

I was wondering if there is a standard way in Typescript to indicate the same.

Any help would be appreciated. Thanks.