Tests for issue #89: incorrect isinstance checks with subclasses of future types

Author: edschofield

future/tests/test_bytes.py

@@ -99,6 +99,16 @@ def test_bytes_fromhex(self):
     def test_isinstance_bytes(self):
         self.assertTrue(isinstance(bytes(b'blah'), bytes))
 
+    def test_isinstance_bytes_subclass(self):
+        """
+        Issue #89
+        """
+        value = bytes(b'abc')
+        class Magic(bytes):
+            pass
+        self.assertTrue(isinstance(value, bytes))
+        self.assertFalse(isinstance(value, Magic))
+
     def test_isinstance_oldbytestrings_bytes(self):
         """
         Watch out for this. Byte-strings produced in various places in Py2

future/tests/test_dict.py

@@ -64,6 +64,16 @@ def test_isinstance_dict(self):
         d = self.d1
         self.assertTrue(isinstance(d, dict))
 
+    def test_isinstance_dict_subclass(self):
+        """
+        Issue #89
+        """
+        value = dict()
+        class Magic(dict):
+            pass
+        self.assertTrue(isinstance(value, dict))
+        self.assertFalse(isinstance(value, Magic))
+
     def test_dict_getitem(self):
         d = dict({'C': 1, 'B': 2, 'A': 3})
         self.assertEqual(d['C'], 1)

future/tests/test_int.py

@@ -49,6 +49,16 @@ def cpython_only(f):
 
 class IntTestCases(unittest.TestCase):
 
+    def test_isinstance_int_subclass(self):
+        """
+        Issue #89
+        """
+        value = int(10)
+        class Magic(int):
+            pass
+        self.assertTrue(isinstance(value, int))
+        self.assertFalse(isinstance(value, Magic))
+
     def test_basic(self):
         self.assertEqual(int(314), 314)
         self.assertEqual(int(3.14), 3)

future/tests/test_list.py

@@ -14,6 +14,16 @@ def test_isinstance_list(self):
         self.assertTrue(isinstance([], list))
         self.assertEqual([1, 2, 3], list([1, 2, 3]))
 
+    def test_isinstance_list_subclass(self):
+        """
+        Issue #89
+        """
+        value = list([1, 2, 3])
+        class Magic(list):
+            pass
+        self.assertTrue(isinstance(value, list))
+        self.assertFalse(isinstance(value, Magic))
+
     def test_list_empty(self):
         """
         list() -> []

future/tests/test_str.py

@@ -94,6 +94,16 @@ def test_str_hasattr_decode(self):
     def test_isinstance_str(self):
         self.assertTrue(isinstance(str('blah'), str))
 
+    def test_isinstance_str_subclass(self):
+        """
+        Issue #89
+        """
+        value = str(u'abc')
+        class Magic(str):
+            pass
+        self.assertTrue(isinstance(value, str))
+        self.assertFalse(isinstance(value, Magic))
+
     def test_str_getitem(self):
         s = str('ABCD')
         self.assertNotEqual(s[0], 65)