ESLint version

8.49.0

What problem do you want to solve?

The Flat Rule Tester currently reports an error when setting the filename of a test case to a non-JavaScript file (e.g. file.ts):
No matching configuration found for file.ts.
As I understand it, this is because files ending with .js are always matched in the flat config system even if there is no files property.

What do you think is the correct solution?

Translate the filename property to files in the config passed to the linter:

...
const itemConfig = { ...item }
if (item.filename) {
	itemConfig.files = [item.filename]
}
...

This ensures that the generated config matches the file.

Participation

• I am willing to submit a pull request for this change.

Additional comments

This problem can also be circumvented by providing a baseConfig but this solution is more ergonomical and this was also not required when using the "legacy" rule tester, so this may be seen as a bug.