René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"--experimental-test-coverage throws TypeError if directory is named file","articleBody":"### Version\n\n24.12.0\n\n### Platform\n\n```text\nMicrosoft Windows NT 10.0.22631.0 x64\n```\n\n### Subsystem\n\ntest_runner\n\n### What steps will reproduce the bug?\n\nRun test node test with `--experimental-test-coverage` on source code with a directory named `file`.\n\n## Steps to Reproduce\n1. Create `src/file/index.js`\n```js\nexport function a() {\n  console.log(\"!\");\n  return 1;\n}\n```\n2. Create `src/file/__tests__/index.spec.js`\n\n```js\nimport { describe, it } from \"node:test\";\nimport assert from \"node:assert/strict\";\nimport { a } from \"../index.js\"\n\ndescribe(\"a\", async function () {\n  it(\"test\",  async function () {\n    const result = a();\n    assert.equal(result, 1);\n  })\n});\n```\n\n3. npm run test with `node --experimental-test-coverage --test \\\"./src/**/__tests__/*.{spec,test}.js\\\"`.\n\n\n## Findings\nhttps://github.com/nodejs/node/blob/dcb9573d0f90ee0d66001d26514bbdcfd8e0610e/lib/internal/test_runner/utils.js#L552-L555\n\nIn `printCoverageBodyTree`, a directory named `file` seems to conflict with internal variable named `file`. Causing it to treat the directory as a file.\n\n### How often does it reproduce? Is there a required condition?\n\n100%\n\n### What is the expected behavior? Why is that the expected behavior?\n\nGenerate test coverage normally.\n\n### What do you see instead?\n\n```\nTypeError: String.prototype.split called on null or undefined\n    at split (\u003canonymous\u003e)\n    at printCoverageBodyTree (node:internal/test_runner/utils:536:44)\n    at printCoverageBodyTree (node:internal/test_runner/utils:565:9)\n    at getCoverageReport (node:internal/test_runner/utils:585:3)\n    at #handleEvent (node:internal/test_runner/reporter/spec:102:16)\n    at SpecReporter._transform (node:internal/test_runner/reporter/spec:112:37)\n    at Transform._write (node:internal/streams/transform:171:8)\n    at writeOrBuffer (node:internal/streams/writable:570:12)\n    at _write (node:internal/streams/writable:499:10)\n    at Writable.write (node:internal/streams/writable:508:10)\nEmitted 'error' event on Readable instance at:\n    at emitErrorNT (node:internal/streams/destroy:170:8)\n    at emitErrorCloseNT (node:internal/streams/destroy:129:3)\n    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)\n```\n\n### Additional information\n\n_No response_","author":{"url":"https://github.com/joshuaavalon","@type":"Person","name":"joshuaavalon"},"datePublished":"2025-12-16T08:35:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/61080/node/issues/61080"}