Python pytest 框架完全指南 - 高效测试最佳实践

# 使用 pip 安装
pip install pytest

# 验证安装
pytest --version

# 安装常用插件
pip install pytest-cov pytest-xdist pytest-html

# test_simple.py

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

def test_add():
    """最简单的 pytest 测试"""
    assert add(2, 3) == 5
    assert add(-1, 1) == 0
    assert add(0, 0) == 0

def test_add_negative():
    """测试负数相加"""
    assert add(-2, -3) == -5

def test_assert_examples():
    """pytest 断言示例"""
    # 相等断言
    assert [1, 2, 3] == [1, 2, 3]

    # 包含断言
    assert "hello" in "hello world"

    # 异常断言
    with pytest.raises(ZeroDivisionError):
        1 / 0

    # 异常信息断言
    with pytest.raises(ValueError, match="must be positive"):
        raise ValueError("value must be positive")

    # 警告断言
    with pytest.warns(DeprecationWarning):
        import warnings
        warnings.warn("deprecated", DeprecationWarning)

class TestStringMethods:
    """使用测试类组织相关测试"""

    def test_upper(self):
        assert "hello".upper() == "HELLO"

    def test_isupper(self):
        assert "HELLO".isupper()
        assert not "Hello".isupper()

    def test_split(self):
        s = "hello world"
        assert s.split() == ["hello", "world"]
        with pytest.raises(TypeError):
            s.split(2)

class TestListMethods:
    """列表相关测试"""

    def test_append(self):
        lst = [1, 2]
        lst.append(3)
        assert lst == [1, 2, 3]

    def test_pop(self):
        lst = [1, 2, 3]
        assert lst.pop() == 3
        assert len(lst) == 2

# 运行当前目录及子目录下所有测试
pytest

# 运行指定文件
pytest test_simple.py

# 运行指定测试函数
pytest test_simple.py::test_add

# 运行指定测试类中的方法
pytest test_simple.py::TestStringMethods::test_upper

# 显示详细输出
pytest -v

# 遇到第一个失败就停止
pytest -x

# 显示局部变量信息
pytest -l

# 显示测试执行时间
pytest --durations=10

import pytest

@pytest.fixture
def sample_data():
    """最简单的 fixture"""
    return {"name": "张三", "age": 25, "city": "北京"}

def test_sample_data(sample_data):
    """通过函数参数注入 fixture"""
    assert sample_data["name"] == "张三"
    assert sample_data["age"] == 25

@pytest.fixture
def db_connection():
    """带有 setup 和 teardown 的 fixture"""
    # setup 阶段
    print("\n连接数据库...")
    connection = {"status": "connected"}

    yield connection  # 返回给测试使用

    # teardown 阶段
    print("\n断开数据库连接...")
    connection["status"] = "disconnected"

def test_db_query(db_connection):
    assert db_connection["status"] == "connected"

@pytest.fixture(scope="module")
def shared_resource():
    """module 级别的 fixture，整个模块只执行一次"""
    resource = {"data": "shared"}
    yield resource

import pytest

@pytest.mark.slow
def test_long_running():
    """标记为慢速测试"""
    import time
    time.sleep(2)

@pytest.mark.skip(reason="功能尚未实现")
def test_not_implemented():
    pass

@pytest.mark.skipif(True, reason="仅在Linux运行")
def test_linux_only():
    pass

@pytest.mark.xfail(reason="已知会失败的测试")
def test_known_failure():
    assert False

# 运行特定标记的测试
# pytest -m slow          # 只运行 slow 标记的测试
# pytest -m "not slow"    # 跳过 slow 标记的测试

# conftest.py
import pytest

@pytest.fixture
def mock_user():
    """所有测试文件都可以使用的共享 fixture"""
    return {"id": 1, "username": "testuser", "role": "admin"}

# pytest.ini 配置文件示例
# [pytest]
# markers =
#     slow: marks tests as slow
#     integration: marks tests as integration tests
# addopts = -v --tb=short