Avoid exception chaining on Python 3.

This avoids exceptions raised by errors='strict' from displaying as
"During handling of the above exception ..." in the backtrace which
can be confusing.

2 files changed, 16 insertions, 4 deletions

diff --git a/tests/test_unidecode.py b/tests/test_unidecode.py
index 5fadf46..4a93301 100644
--- a/tests/test_unidecode.py
+++ b/tests/test_unidecode.py
@@ -525,6 +525,11 @@ class BaseTestUnidecode():
 
         self.assertEqual(5, e.exception.index)
 
+        # This checks that the exception is not chained (i.e. you don't get the
+        # "During handling of the above exception, another exception occurred")
+        if sys.version_info[0] >= 3:
+            self.assertIsNone(e.exception.__context__)
+
     @unittest.skipIf(sys.maxunicode < 0x10000, "narrow build")
     def test_errors_preserve(self):
         s = u"test \U000f0000 test"
@@ -537,6 +542,10 @@ class BaseTestUnidecode():
         with self.assertRaises(UnidecodeError) as e:
             self.unidecode(u"test \U000f0000 test", errors='invalid')
 
+        # This checks that the exception is not chained (i.e. you don't get the
+        # "During handling of the above exception, another exception occurred")
+        if sys.version_info[0] >= 3:
+            self.assertIsNone(e.exception.__context__)
 
 class TestUnidecode(BaseTestUnidecode, unittest.TestCase):
     unidecode = staticmethod(unidecode)
diff --git a/unidecode/__init__.py b/unidecode/__init__.py
index 54c543d..776d6e4 100644
--- a/unidecode/__init__.py
+++ b/unidecode/__init__.py
@@ -65,11 +65,14 @@ def unidecode_expect_ascii(string, errors='ignore', replace_str='?'):
     try:
         bytestring = string.encode('ASCII')
     except UnicodeEncodeError:
-        return _unidecode(string, errors, replace_str)
-    if version_info[0] >= 3:
-        return string
+        pass
     else:
-        return bytestring
+        if version_info[0] >= 3:
+            return string
+        else:
+            return bytestring
+
+    return _unidecode(string, errors, replace_str)
 
 def unidecode_expect_nonascii(string, errors='ignore', replace_str='?'):
     """Transliterate an Unicode object into an ASCII string