What is pytest and why use it?

Question

Accepted Answer

**pytest** is a popular Python **testing framework** with simple syntax and powerful features.

```python
# test_example.py
import pytest

def add(a, b):
    return a + b

# Simple test
def test_add():
    assert add(2, 3) == 5
    assert add(-1, 1) == 0

# Parametrized tests
@pytest.mark.parametrize("a, b, expected", [
    (1, 2, 3),
    (-1, 1, 0),
    (0, 0, 0),
])
def test_add_param(a, b, expected):
    assert add(a, b) == expected

# Fixtures
@pytest.fixture
def sample_user():
    return {"name": "Alice", "age": 25}

def test_user_name(sample_user):
    assert sample_user["name"] == "Alice"

# Exception testing
def test_division_by_zero():
    with pytest.raises(ZeroDivisionError):
        1 / 0

# Run: pytest test_example.py -v
```

**Advantages:**
- No class required (test functions).
- Auto-discovery of test files.
- Rich plugin ecosystem.
- Fixtures for setup/teardown.

Python: What is pytest and why use it?