Could not report code coverage for file in sourcemap

[avivkeller]

Version

v22.9.0

Platform

N/A

Subsystem

test_runner

What steps will reproduce the bug?

Create index.mjs:

export {}
//# sourceMappingURL=index.mjs.map

Create index.mjs.map:

{"version":3,"file":"index.mjs","sourceRoot":"","sources":["index.mjs"],"names":[],"mappings":"AAEA"}

Run:

node --experimental-test-coverage --test index.mjs

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

Every time.

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

Coverage should be reported, or an error explaining why it wasn't is displayed.

What do you see instead?

ℹ Warning: Could not report code coverage. TypeError: Cannot read properties of undefined (reading 'startOffset')

Additional information

CC @nodejs/test_runner

[geeksilva97]

It's not reproducible in 23.10.0

[mcollina]

I investigated this from a clean upstream/main build and could not reproduce it anymore.

I checked out upstream/main, rebuilt node, and then ran the exact repro from the issue:

./node --experimental-test-coverage --test /tmp/.../index.mjs

with:

export {}
//# sourceMappingURL=index.mjs.map

and:

{"version":3,"file":"index.mjs","sourceRoot":"","sources":["index.mjs"],"names":[],"mappings":"AAEA"}

Current behavior is a normal coverage report:

• index.mjs | 100.00 | 100.00 | 100.00
• exit code 0

So this no longer fails with:

Warning: Could not report code coverage. TypeError: Cannot read properties of undefined (reading 'startOffset')

The most likely fix is #55359, which made coverage only use sourcemap remapping when --enable-source-maps is explicitly enabled. That matches this repro, because it only used --experimental-test-coverage and --test.

There was also related hardening in #55055 for invalid or missing sourcemaps.