pytest Fixtures reference

内置fixture

@pytest.fixture 装饰器的形式来使用

capfd
Capture, as text, output to file descriptors 1 and 2.

capfdbinary
Capture, as bytes, output to file descriptors 1 and 2.

caplog
Control logging and access log entries.

capsys
Capture, as text, output to sys.stdout and sys.stderr.

capsysbinary
Capture, as bytes, output to sys.stdout and sys.stderr.

cache
Store and retrieve values across pytest runs.

doctest_namespace
Provide a dict injected into the docstests namespace.

monkeypatch
Temporarily modify classes, functions, dictionaries, os.environ, and other objects.

pytestconfig
Access to configuration values, pluginmanager and plugin hooks.

record_property
Add extra properties to the test.

record_testsuite_property
Add extra properties to the test suite.

recwarn
Record warnings emitted by test functions.

request
Provide information on the executing test function.

testdir
Provide a temporary test directory to aid in running, and testing, pytest plugins.

tmp_path
Provide a pathlib.Path object to a temporary directory which is unique to each test function.

tmp_path_factory
Make session-scoped temporary directories and return pathlib.Path objects.

tmpdir
Provide a py.path.local object to a temporary directory which is unique to each test function; replaced by tmp_path.

tmpdir_factory
Make session-scoped temporary directories and return py.path.local objects; replaced by tmp_path_factory.

fixture 使用

import pytest

@pytest.fixture
def order():
    return []

@pytest.fixture
def outer(order, inner):
    order.append("outer")

class TestOne:
    @pytest.fixture
    def inner(self, order):
        order.append("one")

    def test_order(self, order, outer):
        assert order == ["one", "outer"]

class TestTwo:
    @pytest.fixture
    def inner(self, order):
        order.append("two")

    def test_order(self, order, outer):
        assert order == ["two", "outer"]

因此，当它们运行时，外部将不存在找到内部的问题，因为 pytest 是从测试的角度进行搜索的

跨文件使用多个fixture:conftest.py

tests/
    __init__.py

    conftest.py
        # content of tests/conftest.py
        import pytest

        @pytest.fixture
        def order():
            return []

        @pytest.fixture
        def top(order, innermost):
            order.append("top")

    test_top.py
        # content of tests/test_top.py
        import pytest

        @pytest.fixture
        def innermost(order):
            order.append("innermost top")

        def test_order(order, top):
            assert order == ["innermost top", "top"]

    subpackage/
        __init__.py

        conftest.py
            # content of tests/subpackage/conftest.py
            import pytest

            @pytest.fixture
            def mid(order):
                order.append("mid subpackage")

        test_subpackage.py
            # content of tests/subpackage/test_subpackage.py
            import pytest

            @pytest.fixture
            def innermost(order, mid):
                order.append("innermost subpackage")

            def test_order(order, top):
                assert order == ["mid subpackage", "innermost subpackage", "top"]

第三方插件fixture

tests/
    __init__.py

    conftest.py
        # content of tests/conftest.py
        import pytest

        @pytest.fixture
        def order():
            return []

    subpackage/
        __init__.py

        conftest.py
            # content of tests/subpackage/conftest.py
            import pytest

            @pytest.fixture(autouse=True)
            def mid(order, b_fix):
                order.append("mid subpackage")

        test_subpackage.py
            # content of tests/subpackage/test_subpackage.py
            import pytest

            @pytest.fixture
            def inner(order, mid, a_fix):
                order.append("inner subpackage")

            def test_order(order, inner):
                assert order == ["b_fix", "mid subpackage", "a_fix", "inner subpackage"]

If plugin_a is installed and provides the fixture a_fix, and plugin_b is installed and provides the fixture b_fix, then this is

fixture 执行顺序

三个要素 scope dependencies autouse

• scope

  import pytest
  
  @pytest.fixture(scope="session")
  def order():
      return []
  
  @pytest.fixture
  def func(order):
      order.append("function")
  
  @pytest.fixture(scope="class")
  def cls(order):
      order.append("class")
  
  @pytest.fixture(scope="module")
  def mod(order):
      order.append("module")
  
  @pytest.fixture(scope="package")
  def pack(order):
      order.append("package")
  
  @pytest.fixture(scope="session")
  def sess(order):
      order.append("session")
  
  class TestClass:
      def test_order(self, func, cls, mod, pack, sess, order):
          assert order == ["session", "package", "module", "class", "function"]

• 依赖关系执行

  import pytest
  
  @pytest.fixture
  def order():
      return []
  
  @pytest.fixture
  def a(order):
      order.append("a")
  
  @pytest.fixture
  def b(a, order):
      order.append("b")
  
  @pytest.fixture
  def c(b, order):
      order.append("c")
  
  @pytest.fixture
  def d(c, b, order):
      order.append("d")
  
  @pytest.fixture
  def e(d, b, order):
      order.append("e")
  
  @pytest.fixture
  def f(e, order):
      order.append("f")
  
  @pytest.fixture
  def g(f, c, order):
      order.append("g")
  
  def test_order(g, order):
      assert order == ["a", "b", "c", "d", "e", "f", "g"]

  Autouse fixtures are executed first within their scope

  import pytest
  
  @pytest.fixture
  def order():
      return []
  
  @pytest.fixture
  def a(order):
      order.append("a")
  
  @pytest.fixture
  def b(a, order):
      order.append("b")
  
  @pytest.fixture(autouse=True)
  def c(b, order):
      order.append("c")
  
  @pytest.fixture
  def d(b, order):
      order.append("d")
  
  @pytest.fixture
  def e(d, order):
      order.append("e")
  
  @pytest.fixture
  def f(e, order):
      order.append("f")
  
  @pytest.fixture
  def g(f, c, order):
      order.append("g")
  
  def test_order_and_g(g, order):
      assert order == ["a", "b", "c", "d", "e", "f", "g"]

  看 c和d
  注意 一个 autouse fixture 将自动执行每一个可以到达它的测试，即使他们没有请求它

  import pytest
  
  @pytest.fixture(scope="class")
  def order():
      return []
  
  @pytest.fixture(scope="class", autouse=True)
  def c1(order):
      order.append("c1")
  
  @pytest.fixture(scope="class")
  def c2(order):
      order.append("c2")
  
  @pytest.fixture(scope="class")
  def c3(order, c1):
      order.append("c3")
  
  class TestClassWithC1Request:
      def test_order(self, order, c1, c3):
          assert order == ["c1", "c3"]
  
  class TestClassWithoutC1Request:
      def test_order(self, order, c2):
          assert order == ["c1", "c2"]

import pytest

@pytest.fixture
def order():
    return []

@pytest.fixture
def c1(order):
    order.append("c1")

@pytest.fixture
def c2(order):
    order.append("c2")

class TestClassWithAutouse:
    @pytest.fixture(autouse=True)
    def c3(self, order, c2):
        order.append("c3")

    def test_req(self, order, c1):
        assert order == ["c2", "c3", "c1"]

    def test_no_req(self, order):
        assert order == ["c2", "c3"]

class TestClassWithoutAutouse:
    def test_req(self, order, c1):
        assert order == ["c1"]

    def test_no_req(self, order):
        assert order == []