test_runner: support custom message for expectFailure

[Han5991]

Summary

This PR enhances the expectFailure option in the test runner to accept different types of values, enabling both custom failure labels and robust error validation. This implementation is referenced from and inspired by nodejs/test-runner#10.

Changes

The expectFailure option now supports the following types:

• String: Treated as a failure label (reason).

  test('bug', { expectFailure: 'Investigating' }, ...);

• RegExp / Function / Error Class: Treated as a matcher to validate the thrown error (similar to assert.throws).

  test('regex', { expectFailure: /error message/ }, ...);
  test('class', { expectFailure: RangeError }, ...);

• Object:

  • If it contains label or match properties, it's treated as a configuration object.

    test('config', {
      expectFailure: {
        label: 'Known issue',
        match: /specific error/
      }
    }, ...);

  • Otherwise, it's treated as an object matcher (properties matching).

• Inheritance:

  • Tests now inherit expectFailure from their parent suite. This allows marking an entire suite as expected to fail.

    test('suite', { expectFailure: true }, async (t) => {
      await t.test('subtest', () => { throw new Error(); }); // Passes (expected failure)
    });

References

• Based on concepts from: doc(proposal): expectFailure label and/or matcher test-runner#10

Resolves: #61570

[nodejs-github-bot]

Review requested:

• @nodejs/test_runner

[JakobJingleheimer]

We already have a plan for the value of expectFail: it will soon accept a regular expression to match against.

[Han5991]

We already gave a plan for the value of expectFail: it will soon accept a regular expression to match against.

@JakobJingleheimer
Ah, thanks for the context! I missed that there was an existing plan for error matching.

In that case, I'd be happy to pivot this PR to implement the expectFailure validation logic (accepting a string/regex to match the error) instead of just a message. Does that sound good, or is there someone else already working on it?"

[JakobJingleheimer]

@vassudanagunta you were part of the original discussion; did you happen to start an implementation?

To my knowledge though, no-one has started.

I had planned to pick it up next week, but if you would like to do, go ahead.

If you do, I think it would probably be better to start a new PR than to pivot this one. So open a draft and I'll add it to the test-runner team's kanban board so it gets proper visibility.

[codecov]

Codecov Report

❌ Patch coverage is 87.34177% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.74%. Comparing base (37ff1ea) to head (80928f7).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/test_runner/test.js	87.17%	10 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #61563   +/-   ##
=======================================
  Coverage   89.74%   89.74%           
=======================================
  Files         675      675           
  Lines      204735   204808   +73     
  Branches    39348    39369   +21     
=======================================
+ Hits       183737   183815   +78     
- Misses      13269    13271    +2     
+ Partials     7729     7722    -7     

Files with missing lines	Coverage Δ
lib/internal/test_runner/reporter/tap.js	98.23% <100.00%> (ø)
lib/internal/test_runner/test.js	96.84% <87.17%> (-0.49%)	⬇️

... and 28 files with indirect coverage changes

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[vassudanagunta]

@JakobJingleheimer nope, haven't started this, though I had long ago implemented it in node-test-extra (not yet released).

I think it's important to get the requirements nailed. IMHO, #61570.

[JakobJingleheimer]

As I said, let's put together a proposal in the nodejs/test_runner repo 🙂

[ljharb]

reviewed before reading the discussion; imo a string should work as in this PR whether or not it also supports accepting a regex.

[JakobJingleheimer]

It could do. My concern is supporting this without considering the intended regex feature accidentally precluding that intended feature, or inadvertently creating a breaking change, or creating heavily conflicting PRs (very frustrating for the implementators).

I think we can likely get both; we can easily avoid those problems with a quick proposal so everyone is on the same page 🙂

---

I should start a discussion in that repo?

Please start a proposal like the ones already in that repo 🙂 https://github.com/nodejs/test-runner/tree/main/proposals we can discuss it in that PR

[ljharb]

conflicts fair; as long as the "should expect failure" uses truthiness (does an empty string count as true or false, though?), i can't foresee any semantic collision.

[Han5991]

@ljharb @vassudanagunta

I've opened a proposal PR in the test-runner repository as suggested by @JakobJingleheimer.
It would be great to continue the discussion on the spec details there:
nodejs/test-runner#10

[vassudanagunta]

I think this needs to be documented a little better for the user.

[JakobJingleheimer]

@Han5991 the proposal isn't finished / accepted yet (still hasn't been reviewed by the rest of the test-runner team), so I think it's premature to resume this (the proposal isn't a requirement, but I think it's a good idea and will reduce churn, needless re-reviews, etc—and indeed, there was just earlier today another adjustment to align terms). I do appreciate the enthusiasm 😁

It's added to the team's agenda, so it'll get raised at the next meeting.

[Han5991]

Thanks for letting me know. I'll leave it as a draft until the proposal is finalized.

Resolved by proposal

[JakobJingleheimer]

@Han5991 the proposal is all set, so full-steam ahead 🙂 (or whatever pace you want)

[Han5991]

@JakobJingleheimer
Thank you for taking the time to let me know!

[vassudanagunta]

Some new examples do not jive with the explanatory text. Can reduce the number of examples and shorten the doc without losing any explanatory power.

[vassudanagunta]

Looks like suite-level support for expectFailure was missed the first time around. Should fix this now... I think it will be easy.

[vassudanagunta]

good work!

[Han5991]

@JakobJingleheimer

The PR is ready. Please review it!

[vassudanagunta]

We still have the question about whether todo, skip and expectFailure should be truthy. Probably should be tackled separately from this PR, so I opened an issue: #61815

@JakobJingleheimer @ljharb