Write 1 file. Write all code, no placeholders. Create the file at the EXACT path shown below (relative to the current working directory).

1. tests/test_calculator.py — Tests for a calculator module. Inline a `divide(a, b)` function that divides two numbers and raises ZeroDivisionError for zero denominators. Also inline a `save_result(path, value)` function that writes a float to a file. Write tests that cover: multiple input combinations for divide (positive, zero numerator, negative, fractional results) — use `@pytest.mark.parametrize` for table-driven testing (not separate test functions per case). Test the zero-denominator error case using `pytest.raises(ZeroDivisionError, match="...")` with the `match=` parameter to verify the error message text (not bare `pytest.raises` without match). Test save_result using `tmp_path` fixture (not the deprecated `tmpdir` fixture).
