Rework fixtures

ci/rtd-requirements.txt

@@ -2,3 +2,6 @@
 sphinx >= 1.6.1
 sphinx_rtd_theme
 sphinxcontrib-trio
+# Workaround for this weird issue:
+# https://travis-ci.org/python-trio/pytest-trio/jobs/407495415
+attrs >= 17.4.0

pytest_trio/__init__.py

@@ -1,3 +1,6 @@
 """Top-level package for pytest-trio."""
 
 from ._version import __version__
+from .plugin import trio_fixture
+
+__all__ = ["trio_fixture"]

pytest_trio/_tests/helpers.py

@@ -0,0 +1,15 @@
+import pytest
+
+
+def enable_trio_mode_via_pytest_ini(testdir):
+    testdir.makefile(".ini", pytest="[pytest]\ntrio_mode = true\n")
+
+
+def enable_trio_mode_via_conftest_py(testdir):
+    testdir.makeconftest("from pytest_trio.enable_trio_mode import *")
+
+
+enable_trio_mode = pytest.mark.parametrize(
+    "enable_trio_mode",
+    [enable_trio_mode_via_pytest_ini, enable_trio_mode_via_conftest_py]
+)

pytest_trio/_tests/test_async_yield_fixture.py

@@ -317,39 +317,43 @@ def test_async_yield_fixture_crashed_teardown_allow_other_teardowns(
         import trio
         from async_generator import async_generator, yield_
 
-        events = []
+        setup_events = set()
+        teardown_events = set()
 
         @pytest.fixture
         @async_generator
         async def good_fixture():
             async with trio.open_nursery() as nursery:
-                events.append('good_fixture setup')
+                setup_events.add('good_fixture setup')
                 await yield_(None)
-                events.append('good_fixture teardown')
+                teardown_events.add('good_fixture teardown')
 
         @pytest.fixture
         @async_generator
         async def bad_fixture():
             async with trio.open_nursery() as nursery:
-                events.append('bad_fixture setup')
+                setup_events.add('bad_fixture setup')
                 await yield_(None)
-                events.append('bad_fixture teardown')
+                teardown_events.add('bad_fixture teardown')
                 raise RuntimeError('Crash during fixture teardown')
 
         def test_before():
-            assert not events
+            assert not setup_events
+            assert not teardown_events
 
         @pytest.mark.trio
         async def test_actual_test(bad_fixture, good_fixture):
             pass
 
         def test_after():
-            assert events == [
+            assert setup_events == {
                 'good_fixture setup',
                 'bad_fixture setup',
+            }
+            assert teardown_events == {
                 'bad_fixture teardown',
                 'good_fixture teardown',
-            ]
+            }
     """
         )
     )

pytest_trio/_tests/test_basic.py

@@ -21,7 +21,7 @@ def test_check_async_test_called():
     """
     )
 
-    result = testdir.runpytest()
+    result = testdir.runpytest("-s")
 
     result.assert_outcomes(passed=2)
 

pytest_trio/_tests/test_contextvars.py

@@ -0,0 +1,37 @@
+import pytest
+from pytest_trio import trio_fixture
+
+import contextvars
+
+cv = contextvars.ContextVar("cv", default=None)
+
+
+@trio_fixture
+def cv_checker():
+    assert cv.get() is None
+    yield
+    assert cv.get() is None
+
+
+@trio_fixture
+def cv_setter(cv_checker):
+    assert cv.get() is None
+    token = cv.set("cv_setter")
+    yield
+    assert cv.get() == "cv_setter2"
+    cv.reset(token)
+    assert cv.get() is None
+
+
+@trio_fixture
+def cv_setter2(cv_setter):
+    assert cv.get() == "cv_setter"
+    # Intentionally leak, so can check that this is visible back in cv_setter
+    cv.set("cv_setter2")
+    yield
+    assert cv.get() == "cv_setter2"
+
+
+@pytest.mark.trio
+async def test_contextvars(cv_setter2):
+    assert cv.get() == "cv_setter2"

pytest_trio/_tests/test_fixture_mistakes.py

@@ -0,0 +1,119 @@
+import pytest
+from pytest_trio import trio_fixture
+
+from .helpers import enable_trio_mode
+
+
+def test_trio_fixture_with_non_trio_test(testdir):
+    testdir.makepyfile(
+        """
+        import trio
+        from pytest_trio import trio_fixture
+        import pytest
+
+        @trio_fixture
+        def trio_time():
+            return trio.current_time()
+
+        @pytest.fixture
+        def indirect_trio_time(trio_time):
+            return trio_time + 1
+
+        @pytest.mark.trio
+        async def test_async(mock_clock, trio_time, indirect_trio_time):
+            assert trio_time == 0
+            assert indirect_trio_time == 1
+
+        def test_sync(trio_time):
+            pass
+
+        def test_sync_indirect(indirect_trio_time):
+            pass
+        """
+    )
+
+    result = testdir.runpytest()
+
+    result.assert_outcomes(passed=1, error=2)
+    result.stdout.fnmatch_lines(
+        ["*: Trio fixtures can only be used by Trio tests*"]
+    )
+
+
+def test_trio_fixture_with_wrong_scope_without_trio_mode(testdir):
+    # There's a trick here: when you have a non-function-scope fixture, it's
+    # not instantiated for any particular function (obviously). So... when our
+    # pytest_fixture_setup hook tries to check for marks, it can't normally
+    # see @pytest.mark.trio. So... it's actually almost impossible to have an
+    # async fixture get treated as a Trio fixture *and* have it be
+    # non-function-scope. But, class-scoped fixtures can see marks on the
+    # class, so this is one way (the only way?) it can happen:
+    testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.fixture(scope="class")
+        async def async_class_fixture():
+            pass
+
+        @pytest.mark.trio
+        class TestFoo:
+            async def test_foo(self, async_class_fixture):
+                pass
+        """
+    )
+
+    result = testdir.runpytest()
+
+    result.assert_outcomes(error=1)
+    result.stdout.fnmatch_lines(["*: Trio fixtures must be function-scope*"])
+
+
+@enable_trio_mode
+def test_trio_fixture_with_wrong_scope_in_trio_mode(testdir, enable_trio_mode):
+    enable_trio_mode(testdir)
+
+    testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.fixture(scope="session")
+        async def async_session_fixture():
+            pass
+
+
+        async def test_whatever(async_session_fixture):
+            pass
+        """
+    )
+
+    result = testdir.runpytest()
+
+    result.assert_outcomes(error=1)
+    result.stdout.fnmatch_lines(["*: Trio fixtures must be function-scope*"])
+
+
+@enable_trio_mode
+def test_async_fixture_with_sync_test_in_trio_mode(testdir, enable_trio_mode):
+    enable_trio_mode(testdir)
+
+    testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.fixture
+        async def async_fixture():
+            pass
+
+
+        def test_whatever(async_fixture):
+            pass
+        """
+    )
+
+    result = testdir.runpytest()
+
+    result.assert_outcomes(error=1)
+    result.stdout.fnmatch_lines(
+        ["*: Trio fixtures can only be used by Trio tests*"]
+    )

pytest_trio/_tests/test_fixture_names.py

@@ -0,0 +1,18 @@
+import pytest
+from pytest_trio import trio_fixture
+import trio
+
+
+@trio_fixture
+def fixture_with_unique_name(nursery):
+    nursery.start_soon(trio.sleep_forever)
+
+
+@pytest.mark.trio
+async def test_fixture_names(fixture_with_unique_name):
+    # This might be a bit fragile ... if we rearrange the nursery hierarchy
+    # somehow so it breaks, then we can make it more robust.
+    task = trio.hazmat.current_task()
+    assert task.name == "<test 'test_fixture_names'>"
+    sibling_names = {task.name for task in task.parent_nursery.child_tasks}
+    assert "<fixture 'fixture_with_unique_name'>" in sibling_names