Structure test cases for maximum readability and maintainability by following these principles:
1. Organize each test in three distinct parts separated by blank lines:
- Setup (arrange test fixtures)
- Execution (run unit under test)
- Verification (assert expected results)
2. Minimize intermediate variables - use direct assertions when possible:
Instead of:
```python
matrix = [["cell1", "cell2"], ["cell3", "cell4"]]
expected_html = ""
assert utils.htmlify_matrix(matrix) == expected_html
```
Prefer:
```python
assert utils.htmlify_matrix([["cell1", "cell2"], ["cell3", "cell4"]]) == (
""
)
```
3. Use parameterization to avoid repeated test code:
```python
@pytest.mark.parametrize(
"date", ["1990-12-01", "2050-01-01T00:00:00", "2050-01-01+00:00:00"]
)
def test_validate_date_args_accepts_standard_formats(date):
assert utils.validate_date_args(date)
```
4. Write meaningful assertions that clearly indicate the behavior being tested:
```python
# Weak assertion:
assert "error" in caplog.text
# Better assertion:
assert "invalid date format, expected YYYY-MM-DD" in caplog.text
```