test: resolve flakiness in --mcp flag test #19993
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| // should not have anything on std out | ||
| child.stdout.on("data", data => { | ||
| assert.fail(`Unexpected stdout data: ${data}`); | ||
| }); | ||
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| child.stderr.on("data", data => { | ||
| assert.match(data.toString(), /@eslint\/mcp/u); | ||
| done(); | ||
| if (!doneCalled) { | ||
| assert.match(data.toString(), /@eslint\/mcp/u); | ||
| doneCalled = true; | ||
| done(); | ||
| } |
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Can we just use getOutput here to test both the error message and the (lack of) stdout output, as it's done in other tests?
Lines 1219 to 1224 in 8662ed1
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I did use getOutput first, but the test fails with the error:
Error: Timeout of 10000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.
I think it's because the MCP server process isn't exiting on its own, so getOutput never resolves.
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Ah, of course. Then let's go ahead and merge this change. It looks like this resolves situations like https://github.com/eslint/eslint/actions/runs/16801498351/job/47583769079, where the server manages to print its initial debug message to stderr before the process is terminated.
Prerequisites checklist
What is the purpose of this pull request? (put an "X" next to an item)
[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofix to a rule
[ ] Add a CLI option
[ ] Add something to the core
[x] Other, please explain:
This PR resolves a flakiness issue in the test for starting the MCP server with the --mcp flag.
The test failed intermittently with the error
done() called multiple times. This was because the stderr stream's data event could fire more than once, causing thedone()callback to be executed for each chunk of data.What changes did you make? (Give an overview)
I introduced a boolean flag,
doneCalled, to ensure that thedone()callback is only executed a single time.Is there anything you'd like reviewers to focus on?
See #19951