React-testing-library: Allow `debug` to accept same args at `prettyDOM`

Created on 28 Jan 2020 · 7Comments · Source: testing-library/react-testing-library

Describe the feature you'd like:

When using the debug wrapper in a test, it would be useful to be able to pass additional prettyDOM arguments through from debug

An example use case is being able to extend the number of lines that prettyDOM allows without needing to specify this in env prior to running the tests or needing to use prettyDOM directly

Example:

it('should print all the lines', () => {
    const {  debug } = render(<LargeComponent />);
    const maxLinesForThisTest = 10000;
    debug(undefined, maxLinesForThisTest);
});

I'd be happy to implement this feature, however just curious if there was a specific reason why this was not implemented on the first pass of debug - My team is familiar with using debug for printing out the DOM and we don't often use prettyDOM, and since this wrapper already exists as an api of the render method, allowing users to use debug as the default api makes sense to me

Suggested implementation:

1. First Suggestion:
Additional arguments could be forwarded through debug and passed into prettyDOM in this chunk of code https://github.com/testing-library/react-testing-library/blob/89d11b08c61f3cf5af770c61a03d564b3fdc301c/src/pure.js#L63-L68 (I believe this is the correct place after a little bit of investigation, but am open to other implementations)

debug: (el = baseElement, maxLength, options) => 
   Array.isArray(el) 
     ? // eslint-disable-next-line no-console 
       el.forEach(e => console.log(prettyDOM(e,  maxLength, options))) 
     : // eslint-disable-next-line no-console, 
       console.log(prettyDOM(el, maxLength, options)),

2. Second Suggestion
Keep the implementation of debug the same and add an additional method that always prints the baseElement and allows the user to forward args to prettyDOM - I'm not a big fan of this solution, but 99% of time I've found myself calling debug() without any arguments with the assumption that I wasn't able to pass debug(someElement) as the first argument - so being able to call debug(maxLines) without specifying the debugged element might be nice

debugBaseElement: (maxLength, options) => 
   const el = baseElement;
   Array.isArray(el) 
     ? // eslint-disable-next-line no-console 
       el.forEach(e => console.log(prettyDOM(e,  maxLength, options))) 
     : // eslint-disable-next-line no-console, 
       console.log(prettyDOM(el, maxLength, options)),

Describe alternatives you've considered:

It's possible to get add additional lines by setting an env in the command line
DEBUG_PRINT_LIMIT=10000 npm test however when running jest in --watch mode, this requires us to kill the test runner, update the print limit, then rerun tests which isn't super painful, but adding this inline would be faster
Also possible to use prettyDOM directly from @testing-library/dom, however it's not immediately clear from the docs whether we should be passing in container, asFragment(), or baseElement into this method - Also, since debug is already a wrapper on top of prettyDOM, it makes sense to be able to pass the same args IMO
- Another downside of prettyDOM is that debug wraps prettyDOM in a console.log, whereas prettyDOM requires you to call prettyDOM within a console.log, which makes using the two apis interchangeably potentially confusing

Teachability, Documentation, Adoption, Migration Strategy:

Docs would stay very much the same, only adding a link to prettyDOM from https://testing-library.com/docs/react-testing-library/api#debug and ensure that it's clear the user can forward prettydom arguments from debug

released

Source