jest-validate does not work well with async functions

[ehmicky]

🐛 Bug Report

When validating input using jest-validate's opts.exampleConfig, the validation distinguishes between sync and async functions which creates three issues.

First:

• if opts.exampleConfig uses an async function, functions returning a promise will make the validation fail, but async functions will pass. However one might expect that those two are functionally equivalent.
• if opts.exampleConfig uses a non-async function, functions returning a promise will make the validation pass, but async functions will fail.
• multipleValidOptions() can be used to work around this problem, but I expect very few users will do so.

Second: when using Babel async function are transpiled to non-async function, changing the behavior of jest-validate. Also this means jest-validate always validate against async functions when the code is using Babel.

Third: the error message is not descriptive enough as it says function for both sync and async functions.

Note that the current type checking is using Object.prototype.toString, which returns either '[object Function]' or '[object AsyncFunction]'.

To Reproduce

const { validate } = require('jest-validate')
validate({ name: async () => {} }, { exampleConfig: { name: () => {} } })
/*
  ● Validation Error:

  Option "name" must be of type:
    function
  but instead received:
    function

  Example:
  {
    "name": () => {}
  }
*/

Expected behavior

If a sync function is passed to exampleConfig, async functions should pass.

If an async function is passed to exampleConfig, sync functions should pass.

Link to repl or repo (highly encouraged)

https://repl.it/repls/WelcomeFrizzyService

Run npx envinfo --preset jest

  System:
    OS: Linux 4.18 Ubuntu 18.10 (Cosmic Cuttlefish)
    CPU: (12) x64 Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
  Binaries:
    Node: 11.9.0 - ~/.nvm/versions/node/v11.9.0/bin/node
    Yarn: 1.12.3 - ~/.nvm/versions/node/v11.9.0/bin/yarn
    npm: 6.8.0 - ~/.nvm/versions/node/v11.9.0/bin/npm

[thymikee]

You're right, we don't have a separation of sync/async functions in jest-validate. I'm happy to review a PR fixing current behavior :)

[ehmicky]

@thymikee this is the opposite: there is a separation of sync/async functions in jest-validate, where there probably should not.

As described above this creates issues with Babel transpiling, or when converting from/to an async function from/to a function returning a promise (which should be equivalent).

If you're happy with the following solution, I can submit a PR: if typeof value === 'function' for both values (input value and exampleConfig value), do not make validation condition fail.

See current code.

[thymikee]

I'm cool with that. Just add a test :D

[ehmicky]

Done at #7896

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.