Add bytes.__mod__ tests (test_mod and test_imod) from Py3.5's test_bytes.py

Author: edschofield

tests/test_future/test_bytes.py

@@ -534,8 +534,38 @@ def test_maketrans(self):
         self.assertRaises(ValueError, bytes.maketrans, b'abc', b'xyzq')
         self.assertRaises(TypeError, bytes.maketrans, 'abc', 'def')
 
-    @unittest.expectedFailure
     def test_mod(self):
+        """
+        From Py3.5 test suite (post-PEP 461).
+
+        The bytes mod code is in _PyBytes_Format() in bytesobject.c in Py3.5.
+        """
+        b = b'hello, %b!'
+        orig = b
+        b = b % b'world'
+        self.assertEqual(b, b'hello, world!')
+        self.assertEqual(orig, b'hello, %b!')
+        self.assertFalse(b is orig)
+        b = b'%s / 100 = %d%%'
+        a = b % (b'seventy-nine', 79)
+        self.assertEqual(a, b'seventy-nine / 100 = 79%')
+
+    def test_imod(self):
+        """
+        From Py3.5 test suite (post-PEP 461)
+        """
+        b = b'hello, %b!'
+        orig = b
+        b %= b'world'
+        self.assertEqual(b, b'hello, world!')
+        self.assertEqual(orig, b'hello, %b!')
+        self.assertFalse(b is orig)
+        b = b'%s / 100 = %d%%'
+        b %= (b'seventy-nine', 79)
+        self.assertEqual(b, b'seventy-nine / 100 = 79%')
+
+    @unittest.expectedFailure
+    def test_mod_pep_461(self):
         """
         Test for the PEP 461 functionality (resurrection of %s formatting for
         bytes).