mirror of
https://github.com/unclebob/mutator.git
synced 2026-11-06 18:23:50 +00:00
48 lines
2.0 KiB
Markdown
48 lines
2.0 KiB
Markdown
# Python tests run with mutator's virtualenv
|
|
|
|
Mutator runs a Python project's tests with mutator's own interpreter. That interpreter does not have the project installed, so the baseline fails and no mutants run.
|
|
|
|
## What happened
|
|
|
|
From `/Users/unclebob/projects/crapper`:
|
|
|
|
```bash
|
|
/Users/unclebob/projects/mutator/mutator --use-existing-coverage
|
|
```
|
|
|
|
Every file that still had mutants to run failed the baseline:
|
|
|
|
```text
|
|
Baseline failed for src/crapper/cli.py: /Users/unclebob/projects/mutator/.venv/bin/python -m pytest
|
|
E ModuleNotFoundError: No module named 'crapper'
|
|
```
|
|
|
|
Mutator exited 2. The same suite passes under crapper's virtualenv. `./crapper` collected 120 tests and they passed.
|
|
|
|
This command gets past the baseline, because it names crapper's interpreter:
|
|
|
|
```bash
|
|
/Users/unclebob/projects/mutator/mutator --use-existing-coverage \
|
|
--test-command "/Users/unclebob/projects/crapper/.venv/bin/python -m pytest"
|
|
```
|
|
|
|
## Cause
|
|
|
|
`./mutator` starts `mutator/.venv/bin/python`. `_python_command` in `src/mutator/runner.py` builds the test command from that process:
|
|
|
|
```python
|
|
return f"{sys.executable} -m pytest"
|
|
```
|
|
|
|
`sys.executable` is mutator's Python. Crapper is not installed in `mutator/.venv`.
|
|
|
|
Mutator can still import crapper inside its own process. `ensure_crapper()` in `src/mutator/crapper_link.py` inserts `../crapper/src` onto `sys.path`. Pytest is a new process and does not see that insertion.
|
|
|
|
The baseline also runs in the real tree, before any worker exists. `_prefer_worker_sources` adds `PYTHONPATH` only when the working directory is inside `target/mutation-workers`, so the baseline has no path to the project sources either.
|
|
|
|
## Fix
|
|
|
|
When the project under test has `.venv/bin/python` or `venv/bin/python`, use that interpreter in the test command. The path has to be absolute. Workers do not link `.venv` (`SKIP_LINK` in `src/mutator/workers.py`), so a relative `.venv/bin/python` is missing inside a worker.
|
|
|
|
If the project has no virtualenv, keep using mutator's Python.
|