## TL;DR
Run `python -m pip install hypothesis`. This error means the Hypothesis property-testing library is not installed in the environment running your tests.

```text
ModuleNotFoundError: No module named 'hypothesis'
```

## Fix it

1. **Install it.** Run `python -m pip install hypothesis`.
   - Expected: `Successfully installed hypothesis-...`.

2. **Verify.** Run `python -c "import hypothesis; print(hypothesis.__version__)"`.
   - Expected: a version number prints.

## When this applies
- Tests use `@given` or hypothesis strategies but the env lacks the package.
- Fresh CI image or new virtualenv.

## When it does not apply
- If hypothesis imports but strategies fail, that is a usage error, not a missing install.

## Tool compatibility
hypothesis 6.x, Python 3.8+. `pip install hypothesis`.

## Why it happens
Hypothesis is a third-party package, not stdlib. It must be installed per environment.

## Edge cases
- The `.hypothesis` example database directory is created automatically; you do not need to create it.