From 950e7819a2d020c3f91af20019870afa172ec10a Mon Sep 17 00:00:00 2001
From: isra17 <isra017@gmail.com>
Date: Mon, 15 Sep 2025 11:24:53 -0400
Subject: [PATCH] config: Do not fail if a warning filter category cannot be
 imported

---
 AUTHORS                         |  1 +
 changelog/13732.improvement.rst |  1 +
 src/_pytest/config/__init__.py  | 18 ++++++++++++++++--
 testing/test_config.py          |  2 --
 testing/test_warnings.py        | 27 +++++++++++++++++++++++++++
 5 files changed, 45 insertions(+), 4 deletions(-)
 create mode 100644 changelog/13732.improvement.rst

diff --git a/AUTHORS b/AUTHORS
index f93de06c10d..52363a177bb 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -201,6 +201,7 @@ Ilya Konstantinov
 Ionuț Turturică
 Isaac Virshup
 Israel Fruchter
+Israël Hallé
 Itxaso Aizpurua
 Iwan Briquemont
 Jaap Broekhuizen
diff --git a/changelog/13732.improvement.rst b/changelog/13732.improvement.rst
new file mode 100644
index 00000000000..07b3d620cf6
--- /dev/null
+++ b/changelog/13732.improvement.rst
@@ -0,0 +1 @@
+Previously, when filtering warnings, pytest would fail if the filter referenced a class that could not be imported. Now, this only outputs a message indicating the problem.
diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 0248f046407..8c80405a6ab 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -1965,6 +1965,8 @@ def parse_warning_filter(
         raise UsageError(error_template.format(error=str(e))) from None
     try:
         category: type[Warning] = _resolve_warning_category(category_)
+    except ImportError:
+        raise
     except Exception:
         exc_info = ExceptionInfo.from_current()
         exception_text = exc_info.getrepr(style="native")
@@ -2023,7 +2025,19 @@ def apply_warning_filters(
     # Filters should have this precedence: cmdline options, config.
     # Filters should be applied in the inverse order of precedence.
     for arg in config_filters:
-        warnings.filterwarnings(*parse_warning_filter(arg, escape=False))
+        try:
+            warnings.filterwarnings(*parse_warning_filter(arg, escape=False))
+        except ImportError as e:
+            warnings.warn(
+                f"Failed to import filter module '{e.name}': {arg}", PytestConfigWarning
+            )
+            continue
 
     for arg in cmdline_filters:
-        warnings.filterwarnings(*parse_warning_filter(arg, escape=True))
+        try:
+            warnings.filterwarnings(*parse_warning_filter(arg, escape=True))
+        except ImportError as e:
+            warnings.warn(
+                f"Failed to import filter module '{e.name}': {arg}", PytestConfigWarning
+            )
+            continue
diff --git a/testing/test_config.py b/testing/test_config.py
index 3e8635fd1fc..f2cc139dffa 100644
--- a/testing/test_config.py
+++ b/testing/test_config.py
@@ -2400,8 +2400,6 @@ def test_parse_warning_filter(
         ":" * 5,
         # Invalid action.
         "FOO::",
-        # ImportError when importing the warning class.
-        "::test_parse_warning_filter_failure.NonExistentClass::",
         # Class is not a Warning subclass.
         "::list::",
         # Negative line number.
diff --git a/testing/test_warnings.py b/testing/test_warnings.py
index ff7ee4915c9..399ca586927 100644
--- a/testing/test_warnings.py
+++ b/testing/test_warnings.py
@@ -424,6 +424,33 @@ def test():
     result.stdout.fnmatch_lines(["* 1 failed in*"])
 
 
+def test_accept_unknown_category(pytester: Pytester) -> None:
+    """Category types that can't be imported don't cause failure (#13732)."""
+    pytester.makeini(
+        """
+        [pytest]
+        filterwarnings =
+            always:Failed to import filter module.*:pytest.PytestConfigWarning
+            ignore::foobar.Foobar
+    """
+    )
+    pytester.makepyfile(
+        """
+        def test():
+            pass
+    """
+    )
+    result = pytester.runpytest("-W", "ignore::bizbaz.Bizbaz")
+    result.stdout.fnmatch_lines(
+        [
+            f"*== {WARNINGS_SUMMARY_HEADER} ==*",
+            "*PytestConfigWarning: Failed to import filter module 'foobar': ignore::foobar.Foobar",
+            "*PytestConfigWarning: Failed to import filter module 'bizbaz': ignore::bizbaz.Bizbaz",
+            "* 1 passed, * warning*",
+        ]
+    )
+
+
 class TestDeprecationWarningsByDefault:
     """
     Note: all pytest runs are executed in a subprocess so we don't inherit warning filters