testing: ignore warning entirely otherwise it interferes with the fnmatching

Author: bluetech

testing/test_xfail_behavior.py

@@ -112,6 +112,9 @@ def test_xfail(is_crashing, is_strict, testdir):
 
         import pytest
 
+        # The current implementation emits RuntimeWarning.
+        pytestmark = pytest.mark.filterwarnings('ignore:pytest-forked xfail')
+
         @pytest.mark.xfail(
             reason='The process gets terminated',
             strict={is_strict!s},
@@ -123,9 +126,5 @@ def test_function():
         format(**locals())
     )
 
-    pytest_run_result = testdir.runpytest(
-        test_module,
-        '-ra',
-        '-p', 'no:warnings',  # the current implementation emits RuntimeWarning
-    )
+    pytest_run_result = testdir.runpytest(test_module, '-ra')
     pytest_run_result.stdout.fnmatch_lines(expected_lines)