bun test hangs when running 7+ test files with @xmldom/xmldom + @svgr/core

[hasesho05]

What version of Bun is running?

1.3.5

What platform is your computer?

darwin arm64 (Apple Silicon, macOS 14.5)

What steps can reproduce the bug?

1. Clone https://github.com/hasesho05/bun-test-hang-repro?target=https://github.com
2. bun install
3. bun test → hangs, never exits
4. Each file individually passes fine: bun test tests/parse-01.test.ts

What is the expected behavior?

bun test finishes and exits.

What do you see instead?

Test output appears, but the process never terminates. CPU stays low — not a busy loop, just stuck.

Additional information

Narrowed it down to three conditions that all need to be present:

1. At least one test file using @svgr/core (async transform)
2. @xmldom/xmldom DOMParser called without a custom onError — so it writes [xmldom fatalError] to stderr on parse errors
3. 7 or more test files — 6 is fine, 7 hangs every time

The stderr noise from xmldom (triggered by fast-check feeding random strings into DOMParser) seems to be the trigger when combined with the async svgr transform in a separate file.

Passing a custom onError to suppress the stderr output works around it. Migrated to vitest which runs everything in ~1.6s with no issues.

[github-actions]

Found 3 possible duplicate issues:

1. bun:test freezes (command never exits) after upgrading to 1.0.24 #8314
2. Tests hangs and CPU goes to 99%+ when using bun test #6751
3. xml2js causes Bun to hang after sequential executions. #17224

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