`in` is considered iterating context for some of the Python 3 porting checkers

Close #2186

2 files changed, 6 insertions, 0 deletions

diff --git a/pylint/checkers/python3.py b/pylint/checkers/python3.py
index 497fafadf..d2bc05897 100644
--- a/pylint/checkers/python3.py
+++ b/pylint/checkers/python3.py
@@ -113,6 +113,11 @@ def _in_iterating_context(node):
           isinstance(parent.targets[0], (astroid.List, astroid.Tuple))):
         if len(parent.targets[0].elts) > 1:
             return True
+    # If the call is in a containment check, we consider that to
+    # be an iterating context
+    elif (isinstance(parent, astroid.Compare)
+          and len(parent.ops) == 1 and parent.ops[0][0] == 'in'):
+        return True
     return False
 
 
diff --git a/pylint/test/unittest_checker_python3.py b/pylint/test/unittest_checker_python3.py
index 20d01d413..f8fc22f48 100644
--- a/pylint/test/unittest_checker_python3.py
+++ b/pylint/test/unittest_checker_python3.py
@@ -206,6 +206,7 @@ class TestPython3Checker(testutils.CheckerTestCase):
             'a, b = {}()',
             'max({}())',
             'min({}())',
+            '3 in {}()',
         ]
         non_iterating_code = [
             'x = __({}())',