Check marker arguments

pytest_asyncio/plugin.py

@@ -700,6 +700,8 @@ def pytest_generate_tests(metafunc: Metafunc) -> None:
     marker = metafunc.definition.get_closest_marker("asyncio")
     if not marker:
         return
+    if marker.args or (marker.kwargs and list(marker.kwargs) != ["scope"]):
+        raise ValueError("mark.asyncio accepts only a keyword argument 'scope'.")
     scope = marker.kwargs.get("scope", "function")
     if scope == "function":
         return
@@ -959,7 +961,10 @@ def _retrieve_scope_root(item: Union[Collector, Item], scope: str) -> Collector:
         "package": Package,
         "session": Session,
     }
-    scope_root_type = node_type_by_scope[scope]
+    try:
+        scope_root_type = node_type_by_scope[scope]
+    except KeyError as error:
+        raise ValueError(f"Invalid scope {scope!r}.") from error
     for node in reversed(item.listchain()):
         if isinstance(node, scope_root_type):
             assert isinstance(node, pytest.Collector)

tests/markers/test_invalid_arguments.py

@@ -0,0 +1,104 @@
+from textwrap import dedent
+
+import pytest
+
+
+def test_no_error_when_scope_passed_as_sole_keyword_argument(
+    pytester: pytest.Pytester,
+):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import pytest
+
+            @pytest.mark.asyncio(scope="session")
+            async def test_anything():
+                pass
+            """
+        )
+    )
+    result = pytester.runpytest_subprocess()
+    result.assert_outcomes(passed=1)
+    result.stdout.no_fnmatch_line("*ValueError*")
+
+
+def test_error_when_scope_passed_as_positional_argument(
+    pytester: pytest.Pytester,
+):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import pytest
+
+            @pytest.mark.asyncio("session")
+            async def test_anything():
+                pass
+            """
+        )
+    )
+    result = pytester.runpytest_subprocess()
+    result.assert_outcomes(errors=1)
+    result.stdout.fnmatch_lines(
+        ["*ValueError: mark.asyncio accepts only a keyword argument*"]
+    )
+
+
+def test_error_when_wrong_keyword_argument_is_passed(
+    pytester: pytest.Pytester,
+):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import pytest
+
+            @pytest.mark.asyncio(cope="session")
+            async def test_anything():
+                pass
+            """
+        )
+    )
+    result = pytester.runpytest_subprocess()
+    result.assert_outcomes(errors=1)
+    result.stdout.fnmatch_lines(
+        ["*ValueError: mark.asyncio accepts only a keyword argument 'scope'*"]
+    )
+
+
+def test_error_when_additional_keyword_arguments_are_passed(
+    pytester: pytest.Pytester,
+):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import pytest
+
+            @pytest.mark.asyncio(scope="session", more="stuff")
+            async def test_anything():
+                pass
+            """
+        )
+    )
+    result = pytester.runpytest_subprocess()
+    result.assert_outcomes(errors=1)
+    result.stdout.fnmatch_lines(
+        ["*ValueError: mark.asyncio accepts only a keyword argument*"]
+    )
+
+
+def test_error_when_an_invalid_scope_is_passed(
+    pytester: pytest.Pytester,
+):
+    pytester.makepyfile(
+        dedent(
+            """\
+            import pytest
+
+            @pytest.mark.asyncio(scope="stuff")
+            async def test_anything():
+                pass
+            """
+        )
+    )
+    result = pytester.runpytest_subprocess()
+    result.assert_outcomes(errors=1)
+    result.stdout.fnmatch_lines(["*ValueError: Invalid scope 'stuff'*"])