1import pytest
 2
 3@pytest.fixture
 4def setup():
 5    # 前置准备
 6    print("\nSetup: 准备测试环境")
 7    data = {"name": "test", "value": 42}
 8    yield data  # 返回数据给测试用例
 9    # 后置清理
10    print("\nTeardown: 清理测试环境")
11
12def test_example(setup):
13    print(f"测试中使用fixture数据: {setup}")
14    assert setup["value"] == 42

1@pytest.fixture(autouse=True)
2def auto_fixture():
3    print("\n[Auto] 自动执行的fixture")
4    yield
5    print("\n[Auto] 自动清理")

 1@pytest.fixture
 2def db_connection():
 3    conn = create_connection()
 4    yield conn
 5    conn.close()
 6
 7@pytest.fixture
 8def test_data(db_connection):
 9    db_connection.insert(test_data)
10    yield test_data
11    db_connection.delete(test_data)

1import pytest
2
3@pytest.mark.parametrize("input,expected", [
4    (2, 4),
5    (3, 9),
6    (4, 16),
7])
8def test_square(input, expected):
9    assert input ** 2 == expected

1@pytest.mark.parametrize("a,b,expected", [
2    (2, 3, 5),
3    (0, 0, 0),
4    (-1, 1, 0),
5])
6def test_add(a, b, expected):
7    assert a + b == expected

1@pytest.mark.parametrize("a", [1, 2, 3])
2@pytest.mark.parametrize("b", [4, 5])
3def test_combine(a, b):
4    # 测试组合: (1,4), (1,5), (2,4), (2,5), (3,4), (3,5)
5    assert a + b > 0

1@pytest.mark.parametrize("input,expected", [
2    (2, 4),
3    (3, 9),
4], ids=["two_squared", "three_squared"])
5def test_square(input, expected):
6    assert input ** 2 == expected

1assert a == b           # 相等断言
2assert a != b           # 不相等断言
3assert a in b           # 包含断言
4assert a is None        # None断言
5assert isinstance(a, int)  # 类型断言

1assert result == expected, f"期望{expected}，实际{result}"

 1# 断言抛出异常
 2with pytest.raises(ValueError):
 3    risky_operation()
 4
 5# 断言异常消息
 6with pytest.raises(ValueError, match="divide by zero"):
 7    divide(10, 0)
 8
 9# 获取异常信息
10with pytest.raises(ValueError) as exc_info:
11    divide(10, 0)
12assert "Cannot divide by zero" in str(exc_info.value)

1# 使用pytest的approx
2from pytest import approx
3assert 0.1 + 0.2 == approx(0.3)
4assert 0.1 + 0.2 == approx(0.3, rel=1e-6)
5assert 0.1 + 0.2 == approx(0.3, abs=1e-9)

 1# tests/test_fixture_demo.py
 2import pytest
 3from src.calculator import Calculator
 4
 5@pytest.fixture
 6def calculator():
 7    calc = Calculator()
 8    return calc
 9
10@pytest.fixture(scope="module")
11def module_data():
12    print("\n[Module Setup] 准备模块级数据")
13    data = {"start_value": 100}
14    yield data
15    print("\n[Module Teardown] 清理模块级数据")
16
17def test_add_with_fixture(calculator):
18    result = calculator.add(2, 3)
19    assert result == 5

 1# tests/test_parametrize_demo.py
 2import pytest
 3from src.calculator import Calculator
 4
 5@pytest.fixture
 6def calculator():
 7    return Calculator()
 8
 9@pytest.mark.parametrize("a,b,expected", [
10    (2, 3, 5),
11    (0, 0, 0),
12    (-1, 1, 0),
13    (10, -5, 5),
14])
15def test_add_parametrize(calculator, a, b, expected):
16    result = calculator.add(a, b)
17    assert result == expected