Merge pull request #4620 from Sup3rGeo/bugfix/warningschecker-twice

Bugfix/warningschecker twice

Author: blueyed

changelog/4617.bugfix.rst

@@ -0,0 +1 @@
+Fixed ``pytest.warns`` bug when context manager is reused (e.g. multiple parametrization).

src/_pytest/recwarn.py

@@ -192,6 +192,10 @@ def __exit__(self, *exc_info):
             warnings.warn = self._saved_warn
         super(WarningsRecorder, self).__exit__(*exc_info)
 
+        # Built-in catch_warnings does not reset entered state so we do it
+        # manually here for this context manager to become reusable.
+        self._entered = False
+
 
 class WarningsChecker(WarningsRecorder):
     def __init__(self, expected_warning=None, match_expr=None):

testing/test_warnings.py

@@ -683,3 +683,27 @@ def test_false_function_no_warn(self, testdir):
         self.create_file(testdir, False)
         result = testdir.runpytest()
         result.stdout.fnmatch_lines(["*1 failed in*"])
+
+
+def test_warningschecker_twice(testdir):
+    """Issue #4617"""
+
+    testdir.makepyfile(
+        """
+        import pytest
+        import warnings
+
+        @pytest.mark.parametrize("other", [1, 2])
+        @pytest.mark.parametrize("expectation", [
+            pytest.warns(DeprecationWarning,
+                          match="Message A"),
+            pytest.warns(DeprecationWarning,
+                          match="Message A"),
+        ])
+        def test_parametrized_warnings(other, expectation):
+            with expectation:
+                warnings.warn("Message A", DeprecationWarning)
+        """
+    )
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(["* 4 passed in *"])