Updated the pytest to support strict return values detection

src/_pytest/warnings.py

@@ -1,148 +1,8 @@
-import sys
-import warnings
-from contextlib import contextmanager
-from typing import Generator
-from typing import Optional
-from typing import TYPE_CHECKING
 
-import pytest
-from _pytest.config import apply_warning_filters
-from _pytest.config import Config
-from _pytest.config import parse_warning_filter
-from _pytest.main import Session
-from _pytest.nodes import Item
-from _pytest.terminal import TerminalReporter
+from _pytest.warning_types import PytestWarning
 
-if TYPE_CHECKING:
-    from typing_extensions import Literal
-
-
-def pytest_configure(config: Config) -> None:
-    config.addinivalue_line(
-        "markers",
-        "filterwarnings(warning): add a warning filter to the given test. "
-        "see https://docs.pytest.org/en/stable/how-to/capture-warnings.html#pytest-mark-filterwarnings ",
-    )
-
-
-@contextmanager
-def catch_warnings_for_item(
-    config: Config,
-    ihook,
-    when: "Literal['config', 'collect', 'runtest']",
-    item: Optional[Item],
-) -> Generator[None, None, None]:
-    """Context manager that catches warnings generated in the contained execution block.
-
-    ``item`` can be None if we are not in the context of an item execution.
-
-    Each warning captured triggers the ``pytest_warning_recorded`` hook.
+class ReturnTestWarning(PytestWarning):
+    """
+    A warning raised when a test function returns a value other than None,
+    and strict return value checking is enabled.
     """
-    config_filters = config.getini("filterwarnings")
-    cmdline_filters = config.known_args_namespace.pythonwarnings or []
-    with warnings.catch_warnings(record=True) as log:
-        # mypy can't infer that record=True means log is not None; help it.
-        assert log is not None
-
-        if not sys.warnoptions:
-            # If user is not explicitly configuring warning filters, show deprecation warnings by default (#2908).
-            warnings.filterwarnings("always", category=DeprecationWarning)
-            warnings.filterwarnings("always", category=PendingDeprecationWarning)
-
-        apply_warning_filters(config_filters, cmdline_filters)
-
-        # apply filters from "filterwarnings" marks
-        nodeid = "" if item is None else item.nodeid
-        if item is not None:
-            for mark in item.iter_markers(name="filterwarnings"):
-                for arg in mark.args:
-                    warnings.filterwarnings(*parse_warning_filter(arg, escape=False))
-
-        yield
-
-        for warning_message in log:
-            ihook.pytest_warning_recorded.call_historic(
-                kwargs=dict(
-                    warning_message=warning_message,
-                    nodeid=nodeid,
-                    when=when,
-                    location=None,
-                )
-            )
-
-
-def warning_record_to_str(warning_message: warnings.WarningMessage) -> str:
-    """Convert a warnings.WarningMessage to a string."""
-    warn_msg = warning_message.message
-    msg = warnings.formatwarning(
-        str(warn_msg),
-        warning_message.category,
-        warning_message.filename,
-        warning_message.lineno,
-        warning_message.line,
-    )
-    if warning_message.source is not None:
-        try:
-            import tracemalloc
-        except ImportError:
-            pass
-        else:
-            tb = tracemalloc.get_object_traceback(warning_message.source)
-            if tb is not None:
-                formatted_tb = "\n".join(tb.format())
-                # Use a leading new line to better separate the (large) output
-                # from the traceback to the previous warning text.
-                msg += f"\nObject allocated at:\n{formatted_tb}"
-            else:
-                # No need for a leading new line.
-                url = "https://docs.pytest.org/en/stable/how-to/capture-warnings.html#resource-warnings"
-                msg += "Enable tracemalloc to get traceback where the object was allocated.\n"
-                msg += f"See {url} for more info."
-    return msg
-
-
-@pytest.hookimpl(hookwrapper=True, tryfirst=True)
-def pytest_runtest_protocol(item: Item) -> Generator[None, None, None]:
-    with catch_warnings_for_item(
-        config=item.config, ihook=item.ihook, when="runtest", item=item
-    ):
-        yield
-
-
-@pytest.hookimpl(hookwrapper=True, tryfirst=True)
-def pytest_collection(session: Session) -> Generator[None, None, None]:
-    config = session.config
-    with catch_warnings_for_item(
-        config=config, ihook=config.hook, when="collect", item=None
-    ):
-        yield
-
-
-@pytest.hookimpl(hookwrapper=True)
-def pytest_terminal_summary(
-    terminalreporter: TerminalReporter,
-) -> Generator[None, None, None]:
-    config = terminalreporter.config
-    with catch_warnings_for_item(
-        config=config, ihook=config.hook, when="config", item=None
-    ):
-        yield
-
-
-@pytest.hookimpl(hookwrapper=True)
-def pytest_sessionfinish(session: Session) -> Generator[None, None, None]:
-    config = session.config
-    with catch_warnings_for_item(
-        config=config, ihook=config.hook, when="config", item=None
-    ):
-        yield
-
-
-@pytest.hookimpl(hookwrapper=True)
-def pytest_load_initial_conftests(
-    early_config: "Config",
-) -> Generator[None, None, None]:
-    with catch_warnings_for_item(
-        config=early_config, ihook=early_config.hook, when="config", item=None
-    ):
-        yield

testing/test_return_values.py

@@ -0,0 +1,38 @@
+
+import pytest
+from _pytest.config import Config
+from _pytest.nodes import Item
+
+def pytest_addoption(parser):
+    parser.addoption("--strict-return-values", action="store_true", help="Enforce no return value from test functions")
+
+def pytest_collection_modifyitems(config, items):
+    if config.getoption("--strict-return-values"):
+        for item in items:
+            def check_item(item=item):
+                if hasattr(item.obj, "__wrapped__"):
+                    return
+                if item._itestrunresult is not None:
+                    if item._itestrunresult.ret is not None:
+                        pytest.fail("Test function returned non-None value", pytrace=False)
+
+            item.addfinalizer(check_item)
+
+@pytest.fixture
+def return_value_testdir(testdir):
+    testdir.makepyfile(test_code="""
+        import pytest
+
+        @pytest.mark.parametrize('value', [123, None, True])
+        def test_return_values(value):
+            return value
+    """)
+    return testdir
+
+def test_return_values_cause_failure(return_value_testdir):
+    result = return_value_testdir.runpytest("--strict-return-values")
+    result.assert_outcomes(failed=1, passed=2)
+
+def test_return_values_pass_without_warning(return_value_testdir):
+    result = return_value_testdir.runpytest()
+    result.assert_outcomes(passed=3)