Merge pull request #11160 from lesnek/ml/fix/warinings-recorder-pop

Author: Zac-HD

AUTHORS

@@ -263,6 +263,7 @@ Mickey Pashov
 Mihai Capotă
 Mike Hoyle (hoylemd)
 Mike Lundy
+Milan Lesnek
 Miro Hrončok
 Nathaniel Compton
 Nathaniel Waisbrot

changelog/10701.bugfix.rst

@@ -0,0 +1,2 @@
+:meth:`pytest.WarningsRecorder.pop` will return the most-closely-matched warning in the list,
+rather than the first warning which is an instance of the requested type.

src/_pytest/recwarn.py

@@ -206,10 +206,21 @@ def __len__(self) -> int:
         return len(self._list)
 
     def pop(self, cls: Type[Warning] = Warning) -> "warnings.WarningMessage":
-        """Pop the first recorded warning, raise exception if not exists."""
+        """Pop the first recorded warning which is an instance of ``cls``,
+        but not an instance of a child class of any other match.
+        Raises ``AssertionError`` if there is no match.
+        """
+        best_idx: Optional[int] = None
         for i, w in enumerate(self._list):
-            if issubclass(w.category, cls):
-                return self._list.pop(i)
+            if w.category == cls:
+                return self._list.pop(i)  # exact match, stop looking
+            if issubclass(w.category, cls) and (
+                best_idx is None
+                or not issubclass(w.category, self._list[best_idx].category)
+            ):
+                best_idx = i
+        if best_idx is not None:
+            return self._list.pop(best_idx)
         __tracebackhide__ = True
         raise AssertionError(f"{cls!r} not found in warning list")
 

testing/test_recwarn.py

@@ -1,5 +1,7 @@
 import warnings
+from typing import List
 from typing import Optional
+from typing import Type
 
 import pytest
 from _pytest.pytester import Pytester
@@ -37,6 +39,47 @@ def test_recwarn_captures_deprecation_warning(recwarn: WarningsRecorder) -> None
     assert recwarn.pop(DeprecationWarning)
 
 
+class TestSubclassWarningPop:
+    class ParentWarning(Warning):
+        pass
+
+    class ChildWarning(ParentWarning):
+        pass
+
+    class ChildOfChildWarning(ChildWarning):
+        pass
+
+    @staticmethod
+    def raise_warnings_from_list(_warnings: List[Type[Warning]]):
+        for warn in _warnings:
+            warnings.warn(f"Warning {warn().__repr__()}", warn)
+
+    def test_pop_finds_exact_match(self):
+        with pytest.warns((self.ParentWarning, self.ChildWarning)) as record:
+            self.raise_warnings_from_list(
+                [self.ChildWarning, self.ParentWarning, self.ChildOfChildWarning]
+            )
+
+        assert len(record) == 3
+        _warn = record.pop(self.ParentWarning)
+        assert _warn.category is self.ParentWarning
+
+    def test_pop_raises_if_no_match(self):
+        with pytest.raises(AssertionError):
+            with pytest.warns(self.ParentWarning) as record:
+                self.raise_warnings_from_list([self.ParentWarning])
+            record.pop(self.ChildOfChildWarning)
+
+    def test_pop_finds_best_inexact_match(self):
+        with pytest.warns(self.ParentWarning) as record:
+            self.raise_warnings_from_list(
+                [self.ChildOfChildWarning, self.ChildWarning, self.ChildOfChildWarning]
+            )
+
+        _warn = record.pop(self.ParentWarning)
+        assert _warn.category is self.ChildWarning
+
+
 class TestWarningsRecorderChecker:
     def test_recording(self) -> None:
         rec = WarningsRecorder(_ispytest=True)