Introduce new warning subclasses

Fix #5177

Author: nicoddemus

doc/en/warnings.rst

@@ -415,10 +415,20 @@ The following warning types ares used by pytest and are part of the public API:
 
 .. autoclass:: pytest.PytestWarning
 
-.. autoclass:: pytest.PytestDeprecationWarning
+.. autoclass:: pytest.PytestAssertRewriteWarning
 
-.. autoclass:: pytest.RemovedInPytest4Warning
+.. autoclass:: pytest.PytestCacheWarning
+
+.. autoclass:: pytest.PytestCollectionWarning
+
+.. autoclass:: pytest.PytestConfigWarning
+
+.. autoclass:: pytest.PytestDeprecationWarning
 
 .. autoclass:: pytest.PytestExperimentalApiWarning
 
+.. autoclass:: pytest.PytestUnhandledCoroutineWarning
+
 .. autoclass:: pytest.PytestUnknownMarkWarning
+
+.. autoclass:: pytest.RemovedInPytest4Warning

src/_pytest/assertion/rewrite.py

@@ -268,11 +268,13 @@ def mark_rewrite(self, *names):
         self._marked_for_rewrite_cache.clear()
 
     def _warn_already_imported(self, name):
-        from _pytest.warning_types import PytestWarning
+        from _pytest.warning_types import PytestAssertRewriteWarning
         from _pytest.warnings import _issue_warning_captured
 
         _issue_warning_captured(
-            PytestWarning("Module already imported so cannot be rewritten: %s" % name),
+            PytestAssertRewriteWarning(
+                "Module already imported so cannot be rewritten: %s" % name
+            ),
             self.config.hook,
             stacklevel=5,
         )
@@ -819,11 +821,13 @@ def visit_Assert(self, assert_):
 
         """
         if isinstance(assert_.test, ast.Tuple) and len(assert_.test.elts) >= 1:
-            from _pytest.warning_types import PytestWarning
+            from _pytest.warning_types import PytestAssertRewriteWarning
             import warnings
 
             warnings.warn_explicit(
-                PytestWarning("assertion is always true, perhaps remove parentheses?"),
+                PytestAssertRewriteWarning(
+                    "assertion is always true, perhaps remove parentheses?"
+                ),
                 category=None,
                 filename=str(self.module_path),
                 lineno=assert_.lineno,
@@ -887,10 +891,10 @@ def warn_about_none_ast(self, node, module_path, lineno):
         val_is_none = ast.Compare(node, [ast.Is()], [AST_NONE])
         send_warning = ast.parse(
             """
-from _pytest.warning_types import PytestWarning
+from _pytest.warning_types import PytestAssertRewriteWarning
 from warnings import warn_explicit
 warn_explicit(
-    PytestWarning('asserting the value None, please use "assert is None"'),
+    PytestAssertRewriteWarning('asserting the value None, please use "assert is None"'),
     category=None,
     filename={filename!r},
     lineno={lineno},

src/_pytest/cacheprovider.py

@@ -60,10 +60,10 @@ def cache_dir_from_config(config):
 
     def warn(self, fmt, **args):
         from _pytest.warnings import _issue_warning_captured
-        from _pytest.warning_types import PytestWarning
+        from _pytest.warning_types import PytestCacheWarning
 
         _issue_warning_captured(
-            PytestWarning(fmt.format(**args) if args else fmt),
+            PytestCacheWarning(fmt.format(**args) if args else fmt),
             self._config.hook,
             stacklevel=3,
         )

src/_pytest/config/__init__.py

@@ -32,7 +32,7 @@
 from _pytest.compat import safe_str
 from _pytest.outcomes import fail
 from _pytest.outcomes import Skipped
-from _pytest.warning_types import PytestWarning
+from _pytest.warning_types import PytestConfigWarning
 
 hookimpl = HookimplMarker("pytest")
 hookspec = HookspecMarker("pytest")
@@ -307,7 +307,7 @@ def parse_hookspec_opts(self, module_or_class, name):
     def register(self, plugin, name=None):
         if name in ["pytest_catchlog", "pytest_capturelog"]:
             warnings.warn(
-                PytestWarning(
+                PytestConfigWarning(
                     "{} plugin has been merged into the core, "
                     "please remove it from your requirements.".format(
                         name.replace("_", "-")
@@ -574,7 +574,7 @@ def import_plugin(self, modname, consider_entry_points=False):
             from _pytest.warnings import _issue_warning_captured
 
             _issue_warning_captured(
-                PytestWarning("skipped plugin %r: %s" % (modname, e.msg)),
+                PytestConfigWarning("skipped plugin %r: %s" % (modname, e.msg)),
                 self.hook,
                 stacklevel=1,
             )
@@ -863,7 +863,7 @@ def _preparse(self, args, addopts=True):
                 from _pytest.warnings import _issue_warning_captured
 
                 _issue_warning_captured(
-                    PytestWarning(
+                    PytestConfigWarning(
                         "could not load initial conftests: {}".format(e.path)
                     ),
                     self.hook,

src/_pytest/junitxml.py

@@ -307,9 +307,11 @@ def record_xml_attribute(request):
     The fixture is callable with ``(name, value)``, with value being
     automatically xml-encoded
     """
-    from _pytest.warning_types import PytestWarning
+    from _pytest.warning_types import PytestExperimentalApiWarning, PytestWarning
 
-    request.node.warn(PytestWarning("record_xml_attribute is an experimental feature"))
+    request.node.warn(
+        PytestExperimentalApiWarning("record_xml_attribute is an experimental feature")
+    )
 
     # Declare noop
     def add_attr_noop(name, value):

src/_pytest/python.py

@@ -45,7 +45,8 @@
 from _pytest.outcomes import fail
 from _pytest.outcomes import skip
 from _pytest.pathlib import parts
-from _pytest.warning_types import PytestWarning
+from _pytest.warning_types import PytestCollectionWarning
+from _pytest.warning_types import PytestUnhandledCoroutineWarning
 
 
 def pyobj_property(name):
@@ -171,7 +172,7 @@ def pytest_pyfunc_call(pyfuncitem):
         msg += "  - pytest-asyncio\n"
         msg += "  - pytest-trio\n"
         msg += "  - pytest-tornasync"
-        warnings.warn(PytestWarning(msg.format(pyfuncitem.nodeid)))
+        warnings.warn(PytestUnhandledCoroutineWarning(msg.format(pyfuncitem.nodeid)))
         skip(msg="coroutine function and no async plugin installed (see warnings)")
     funcargs = pyfuncitem.funcargs
     testargs = {arg: funcargs[arg] for arg in pyfuncitem._fixtureinfo.argnames}
@@ -221,7 +222,7 @@ def pytest_pycollect_makeitem(collector, name, obj):
         if not (isfunction(obj) or isfunction(get_real_func(obj))):
             filename, lineno = getfslineno(obj)
             warnings.warn_explicit(
-                message=PytestWarning(
+                message=PytestCollectionWarning(
                     "cannot collect %r because it is not a function." % name
                 ),
                 category=None,
@@ -233,7 +234,7 @@ def pytest_pycollect_makeitem(collector, name, obj):
                 res = Function(name, parent=collector)
                 reason = deprecated.YIELD_TESTS.format(name=name)
                 res.add_marker(MARK_GEN.xfail(run=False, reason=reason))
-                res.warn(PytestWarning(reason))
+                res.warn(PytestCollectionWarning(reason))
             else:
                 res = list(collector._genfunctions(name, obj))
             outcome.force_result(res)
@@ -721,15 +722,15 @@ def collect(self):
             return []
         if hasinit(self.obj):
             self.warn(
-                PytestWarning(
+                PytestCollectionWarning(
                     "cannot collect test class %r because it has a "
                     "__init__ constructor" % self.obj.__name__
                 )
             )
             return []
         elif hasnew(self.obj):
             self.warn(
-                PytestWarning(
+                PytestCollectionWarning(
                     "cannot collect test class %r because it has a "
                     "__new__ constructor" % self.obj.__name__
                 )

src/_pytest/warning_types.py

@@ -9,28 +9,43 @@ class PytestWarning(UserWarning):
     """
 
 
-class PytestUnknownMarkWarning(PytestWarning):
+class PytestAssertRewriteWarning(PytestWarning):
     """
     Bases: :class:`PytestWarning`.
 
-    Warning emitted on use of unknown markers.
-    See https://docs.pytest.org/en/latest/mark.html for details.
+    Warning emitted by the pytest assert rewrite module.
     """
 
 
-class PytestDeprecationWarning(PytestWarning, DeprecationWarning):
+class PytestCacheWarning(PytestWarning):
     """
-    Bases: :class:`pytest.PytestWarning`, :class:`DeprecationWarning`.
+    Bases: :class:`PytestWarning`.
 
-    Warning class for features that will be removed in a future version.
+    Warning emitted by the cache plugin in various situations.
     """
 
 
-class RemovedInPytest4Warning(PytestDeprecationWarning):
+class PytestConfigWarning(PytestWarning):
     """
-    Bases: :class:`pytest.PytestDeprecationWarning`.
+    Bases: :class:`PytestWarning`.
 
-    Warning class for features scheduled to be removed in pytest 4.0.
+    Warning emitted for configuration issues.
+    """
+
+
+class PytestCollectionWarning(PytestWarning):
+    """
+    Bases: :class:`PytestWarning`.
+
+    Warning emitted when pytest is not able to collect a file or symbol in a module.
+    """
+
+
+class PytestDeprecationWarning(PytestWarning, DeprecationWarning):
+    """
+    Bases: :class:`pytest.PytestWarning`, :class:`DeprecationWarning`.
+
+    Warning class for features that will be removed in a future version.
     """
 
 
@@ -51,6 +66,33 @@ def simple(cls, apiname):
         )
 
 
+class PytestUnhandledCoroutineWarning(PytestWarning):
+    """
+    Bases: :class:`PytestWarning`.
+
+    Warning emitted when pytest encounters a test function which is a coroutine,
+    but it was not handled by any async-aware plugin. Coroutine test functions
+    are not natively supported.
+    """
+
+
+class PytestUnknownMarkWarning(PytestWarning):
+    """
+    Bases: :class:`PytestWarning`.
+
+    Warning emitted on use of unknown markers.
+    See https://docs.pytest.org/en/latest/mark.html for details.
+    """
+
+
+class RemovedInPytest4Warning(PytestDeprecationWarning):
+    """
+    Bases: :class:`pytest.PytestDeprecationWarning`.
+
+    Warning class for features scheduled to be removed in pytest 4.0.
+    """
+
+
 @attr.s
 class UnformattedWarning(object):
     """Used to hold warnings that need to format their message at runtime, as opposed to a direct message.

src/pytest.py

@@ -35,8 +35,13 @@
 from _pytest.python_api import raises
 from _pytest.recwarn import deprecated_call
 from _pytest.recwarn import warns
+from _pytest.warning_types import PytestAssertRewriteWarning
+from _pytest.warning_types import PytestCacheWarning
+from _pytest.warning_types import PytestCollectionWarning
+from _pytest.warning_types import PytestConfigWarning
 from _pytest.warning_types import PytestDeprecationWarning
 from _pytest.warning_types import PytestExperimentalApiWarning
+from _pytest.warning_types import PytestUnhandledCoroutineWarning
 from _pytest.warning_types import PytestUnknownMarkWarning
 from _pytest.warning_types import PytestWarning
 from _pytest.warning_types import RemovedInPytest4Warning
@@ -67,13 +72,18 @@
     "Module",
     "Package",
     "param",
+    "PytestAssertRewriteWarning",
+    "PytestCacheWarning",
+    "PytestCollectionWarning",
+    "PytestConfigWarning",
     "PytestDeprecationWarning",
     "PytestExperimentalApiWarning",
+    "PytestUnhandledCoroutineWarning",
+    "PytestUnknownMarkWarning",
     "PytestWarning",
     "raises",
     "register_assert_rewrite",
     "RemovedInPytest4Warning",
-    "PytestUnknownMarkWarning",
     "Session",
     "set_trace",
     "skip",

testing/test_warnings.py

@@ -630,7 +630,7 @@ def test():
 class TestAssertionWarnings:
     @staticmethod
     def assert_result_warns(result, msg):
-        result.stdout.fnmatch_lines(["*PytestWarning: %s*" % msg])
+        result.stdout.fnmatch_lines(["*PytestAssertRewriteWarning: %s*" % msg])
 
     def test_tuple_warning(self, testdir):
         testdir.makepyfile(