From ce0b0518c780c498025f4252edd9fb587b2aaa37 Mon Sep 17 00:00:00 2001
From: Ronny Pfannschmidt <ronny.pfannschmidt@redhat.com>
Date: Fri, 26 Oct 2018 09:01:25 +0200
Subject: [PATCH] fix #4243 - support positional argument stacklevel on python2

---
 changelog/4243.bugfix.rst |  1 +
 src/_pytest/recwarn.py    | 18 ++++++++++++------
 testing/test_recwarn.py   |  6 ++++++
 3 files changed, 19 insertions(+), 6 deletions(-)
 create mode 100644 changelog/4243.bugfix.rst

diff --git a/changelog/4243.bugfix.rst b/changelog/4243.bugfix.rst
new file mode 100644
index 000000000..6a8bed895
--- /dev/null
+++ b/changelog/4243.bugfix.rst
@@ -0,0 +1 @@
+Fix regression when ``stacklevel`` for warnings was passed as positional argument on python2.
diff --git a/src/_pytest/recwarn.py b/src/_pytest/recwarn.py
index 4049110c5..4f3ab7f29 100644
--- a/src/_pytest/recwarn.py
+++ b/src/_pytest/recwarn.py
@@ -156,21 +156,27 @@ class WarningsRecorder(warnings.catch_warnings):
         # trivial patching of `warnings.warn` seems to be enough somehow?
         if six.PY2:
 
-            def warn(*args, **kwargs):
-                kwargs.setdefault("stacklevel", 1)
-                kwargs["stacklevel"] += 1
+            def warn(message, category=None, stacklevel=1):
+                # duplicate the stdlib logic due to
+                # bad handing in the c version of warnings
+                if isinstance(message, Warning):
+                    category = message.__class__
+                # Check category argument
+                if category is None:
+                    category = UserWarning
+                assert issubclass(category, Warning)
 
                 # emulate resetting the warn registry
-                f_globals = sys._getframe(kwargs["stacklevel"] - 1).f_globals
+                f_globals = sys._getframe(stacklevel).f_globals
                 if "__warningregistry__" in f_globals:
                     orig = f_globals["__warningregistry__"]
                     f_globals["__warningregistry__"] = None
                     try:
-                        return self._saved_warn(*args, **kwargs)
+                        return self._saved_warn(message, category, stacklevel + 1)
                     finally:
                         f_globals["__warningregistry__"] = orig
                 else:
-                    return self._saved_warn(*args, **kwargs)
+                    return self._saved_warn(message, category, stacklevel + 1)
 
             warnings.warn, self._saved_warn = warn, warnings.warn
         return self
diff --git a/testing/test_recwarn.py b/testing/test_recwarn.py
index 726f43763..223521a5e 100644
--- a/testing/test_recwarn.py
+++ b/testing/test_recwarn.py
@@ -46,6 +46,12 @@ class TestWarningsRecorderChecker(object):
             assert values is rec.list
             pytest.raises(AssertionError, "rec.pop()")
 
+    @pytest.mark.issue(4243)
+    def test_warn_stacklevel(self):
+        rec = WarningsRecorder()
+        with rec:
+            warnings.warn("test", DeprecationWarning, 2)
+
     def test_typechecking(self):
         from _pytest.recwarn import WarningsChecker