--experimental-test-coverage empty since 23.5.0

Version

v24.1.0

Platform

Darwin 24.4.0 Darwin Kernel Version 24.4.0: Fri Apr 11 18:34:14 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T8122 arm64

Subsystem

test

What steps will reproduce the bug?

import { test } from 'node:test'

console.log(process.versions.node)

test('foo', () => {
  if (false) {
    throw new Error('Failed')
  } else {
    // pass
  }
})

% node --experimental-test-coverage --test i.js    
24.1.0
✔ foo (0.502334ms)
ℹ tests 1
ℹ suites 0
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 57.841208
ℹ start of coverage report
ℹ ----------------------------------------------------------
ℹ file      | line % | branch % | funcs % | uncovered lines
ℹ ----------------------------------------------------------
ℹ ----------------------------------------------------------
ℹ all files | 100.00 |   100.00 |  100.00 | 
ℹ ----------------------------------------------------------
ℹ end of coverage report

Since 23.5.0:

% nvm use 23.5
Now using node v23.5.0 (npm v10.9.2)
% node --experimental-test-coverage --test i.js
23.5.0
✔ foo (0.330042ms)
ℹ tests 1
ℹ suites 0
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 64.134167
ℹ start of coverage report
ℹ -----------------------------------------------------
ℹ file | line % | branch % | funcs % | uncovered lines
ℹ -----------------------------------------------------
ℹ -----------------------------------------------------
ℹ …les | 100.00 |   100.00 |  100.00 | 
ℹ -----------------------------------------------------
ℹ end of coverage report

23.4.0 was fine:

% nvm use 23.4                                 
Now using node v23.4.0 (npm v10.9.2)
% node --experimental-test-coverage --test i.js
23.4.0
✔ foo (0.326084ms)
ℹ tests 1
ℹ suites 0
ℹ pass 1
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 62.499375
ℹ start of coverage report
ℹ -------------------------------------------------------
ℹ file   | line % | branch % | funcs % | uncovered lines
ℹ -------------------------------------------------------
ℹ i.js   |  91.67 |    66.67 |  100.00 | 7
ℹ -------------------------------------------------------
ℹ …files |  91.67 |    66.67 |  100.00 | 
ℹ -------------------------------------------------------
ℹ end of coverage report

How often does it reproduce? Is there a required condition?

Every time

What is the expected behavior? Why is that the expected behavior?

Output on 23.4.0 (see above) was fine
Non-empty coverage report, reporting line 7 in the above example as uncovered

What do you see instead?

Empty coverage

Additional information

No response

Start with the supplied i.js reproducer and run it with Node.js 23.4.0, 23.5.0, and 24.1.0 using --experimental-test-coverage --test. Trace the test-coverage reporting path to determine why the later versions omit the file, then verify that the report is non-empty and identifies line 7 as uncovered.