Fix #3671 - filterwarnings Is an Unregistered Marker

AUTHORS

@@ -182,6 +182,7 @@ Russel Winder
 Ryan Wooden
 Samuel Dion-Girardeau
 Samuele Pedroni
+Sankt Petersbug
 Segev Finer
 Serhii Mozghovyi
 Simon Gomizelj

changelog/3671.bugfix.rst

@@ -0,0 +1 @@
+Fix ``filterwarnings`` mark not registered

src/_pytest/warnings.py

@@ -49,6 +49,14 @@ def pytest_addoption(parser):
     )
 
 
+def pytest_configure(config):
+    config.addinivalue_line(
+        "markers",
+        "filterwarnings(warning): add a warning filter to the given test. "
+        "see http://pytest.org/latest/warnings.html#pytest-mark-filterwarnings ",
+    )
+
+
 @contextmanager
 def catch_warnings_for_item(item):
     """

testing/test_warnings.py

@@ -287,3 +287,18 @@ def test():
     )
     result = testdir.runpytest("-W", "always")
     result.stdout.fnmatch_lines(["*= 1 passed, 1 warnings in *"])
+
+
+def test_filterwarnings_mark_registration(testdir):
+    """Ensure filterwarnings mark is registered"""
+    testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.filterwarnings('error')
+        def test_func():
+            pass
+    """
+    )
+    result = testdir.runpytest("--strict")
+    assert result.ret == 0