1 files changed, 6 insertions, 0 deletions
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 8158f783cc..caf28fd346 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -779,6 +779,12 @@ class BytesTest(BaseBytesTest, unittest.TestCase):
             def __index__(self):
                 return 42
         self.assertEqual(bytes(A()), b'a')
+        # Issue #25766
+        class A(str):
+            def __bytes__(self):
+                return b'abc'
+        self.assertEqual(bytes(A('\u20ac')), b'abc')
+        self.assertEqual(bytes(A('\u20ac'), 'iso8859-15'), b'\xa4')
         # Issue #24731
         class A:
             def __bytes__(self):