micropython / micropython/micropython
tests: cmdline/repl_lock.py and repl_cont.py intermittent failures
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Description
Two REPL tests fail intermittently on CI:
cmdline/repl_lock.py — fails on QEMU ARM and RISCV64. The expected
output shows >>> micropython.heap_lock() but the actual output drops
the >>> prompt prefix. Observed 3 times in 20 runs with logs. This is
a REPL prompt timing issue under QEMU emulation.
cmdline/repl_cont.py — fails on macOS. Differences in quote escaping
in REPL continuation prompts ("'" vs '\''). Observed once in 20 runs.
The macOS job has historically been the second most failure-prone job
(4.3% failure rate, 25 failures over 14 months) with all failures
attributed to REPL-related issues. The August 2025 spike (11 macOS
failures) correlates with the GitHub Actions macOS 15 runner migration.
PR #18861 now ignores these failures in CI.
See analysis: https://gist.github.com/andrewleech/5686ed5242e0948d8679c432579e002e
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with cmdline/repl_lock.py and cmdline/repl_cont.py, then review the linked failure analysis and CI logs for the affected QEMU and macOS jobs. Re-run both tests repeatedly on those targets and compare prompt output and quote escaping; done means the intermittent mismatches are resolved rather than merely ignored by PR #18861.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- cli, testing
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100