Cache exceptions raised by shared fixtures

pytest_asyncio_cooperative/fixtures.py

@@ -117,10 +117,16 @@ async def __call__(self, *args, **kwargs):
         async with self.lock:
             if hasattr(self, "value"):
                 return self.value
-            if inspect.iscoroutinefunction(self.wrapped_func):
-                self.value = await self.wrapped_func(*args, **kwargs)
-            else:
-                self.value = self.wrapped_func(*args, **kwargs)
+            if hasattr(self, "exception"):
+                raise self.exception
+            try:
+                if inspect.iscoroutinefunction(self.wrapped_func):
+                    self.value = await self.wrapped_func(*args, **kwargs)
+                else:
+                    self.value = self.wrapped_func(*args, **kwargs)
+            except Exception as e:
+                self.exception = e
+                raise
             return self.value
 
 
@@ -161,10 +167,16 @@ def __next__(self):
             return self.gen.__next__()
         if hasattr(self, "value"):
             return self.value
+        if hasattr(self, "exception"):
+            raise self.exception
         else:
-            gen = self.wrapped_func(*self.args)
-            self.gen = gen
-            self.value = gen.__next__()
+            try:
+                gen = self.wrapped_func(*self.args)
+                self.gen = gen
+                self.value = gen.__next__()
+            except Exception as e:
+                self.exception = e
+                raise
             return self.value
 
 
@@ -206,10 +218,16 @@ async def __anext__(self):
         async with self.lock:
             if hasattr(self, "value"):
                 return self.value
+            if hasattr(self, "exception"):
+                raise self.exception
             else:
-                gen = self.wrapped_func(*self.args)
-                self.gen = gen
-                self.value = await gen.__anext__()
+                try:
+                    gen = self.wrapped_func(*self.args)
+                    self.gen = gen
+                    self.value = await gen.__anext__()
+                except Exception as e:
+                    self.exception = e
+                    raise
                 return self.value
 
 

tests/test_fixture.py

@@ -1,3 +1,5 @@
+import pytest
+
 def test_function_fixture(testdir):
     testdir.makepyfile(
         """
@@ -456,3 +458,44 @@ async def test_a(aaa, bbb):
     result = testdir.runpytest("--asyncio-task-timeout=3")
 
     result.assert_outcomes(passed=1)
+
+
+@pytest.mark.parametrize("scope", ["module", "session"])
+@pytest.mark.parametrize("def_", ["def", "async def"])
+@pytest.mark.parametrize("ret", ["return", "yield"])
+@pytest.mark.parametrize("fail", [False, True])
+def test_shared_fixture_caching(testdir, scope, def_, ret, fail):
+    testdir.makepyfile(
+        f"""
+        import pytest
+        import time
+
+        called = False
+        @pytest.fixture({scope=})
+        {def_} shared_fixture():
+            global called
+            if called:
+                assert {fail}
+            else:
+                called = True
+                assert not {fail}
+            {ret}
+
+        @pytest.mark.asyncio_cooperative
+        async def test_a(shared_fixture):
+            assert True
+
+        @pytest.mark.asyncio_cooperative
+        async def test_b(shared_fixture):
+            assert True
+    """
+    )
+
+    result = testdir.runpytest()
+
+    if fail:
+        result.assert_outcomes(failed=2)
+        # Should be errors instead of failures
+        # https://github.com/willemt/pytest-asyncio-cooperative/issues/42
+    else:
+        result.assert_outcomes(passed=2)