[Bug]: unexpected expect.extend behaviour about playwright HOT 4 CLOSED

Happy to hear you solved your problem. As you can see, I deleted my comment with the recommendation because I really don't want anybody who doesn't understand the consequences of importing a private package to see it. But you seem to be aware of that, so have fun! :D I'll close the issue.

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As a workaround you can save original matchers before extending the expect and later call them from your implementation:

const originalToHaveText = (baseExpect as any).toHaveText; 

const dateExpect = baseExpect.extend({
  async toHaveText(this: ExpectMatcherState, date: Date, expected: string | RegExp, options?: { ignoreCase?: boolean, timeout?: number }): Promise<MatcherReturnType> {
...
      } else {
        originalToHaveText.call(baseExpect(date as Locator), expected, options);
      }
...
  },
});

I can't get that to work either ... originalToHaveText is (...u)=>new i(!1,...u) which seems to return an AsymmetricMatcher when called:

i {
  '$$typeof': Symbol(jest.asymmetricMatcher),
  sample: [ [ 'Node.js', 'Python', 'Java', '.NET' ], undefined ],
  inverse: false
}

Didn't work as-is for me (Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './lib/matchers/matchers' is not defined by "exports" in .../package.json, but I got it working in the import-internal-matchers branch of the demo repo.

It's a bit tricky to actually get the path of matchers.js reliably (playwright might not be hoisted), but the demo code is currently working for all combinations of npm/yarn/pnpm, esm/cjs and Node 16/18/20/22 (at least on macOS).

I think I will go with this approach and cross my fingers it doesn't break too often. Thanks for the help!

PS. It would obviously be totally awesome if @playwright/test had a public export of all the built-in matchers (including toBe etc from the bundled expect library) so we could reuse and extend them in a supported way. Getting the MatcherReturnType right is quite some work.

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