Make the recently added compat module standalone.

mig/shared/compat.py

@@ -31,13 +31,19 @@
 """
 
 from __future__ import absolute_import
+from past.builtins import basestring
 
 import codecs
 import sys
 
 PY2 = sys.version_info[0] < 3
+_TYPE_UNICODE = type(u"")
 
-from mig.shared.base import STR_KIND, _force_default_coding
+
+def _is_unicode(val):
+    """Return boolean indicating if the value is a unicode string.
+    """
+    return (type(val) == _TYPE_UNICODE)
 
 
 def ensure_native_string(string_or_bytes):
@@ -50,13 +56,16 @@ def ensure_native_string(string_or_bytes):
     valid textual string) will trigger a UnicodeDecodeError on PY3.
     Force the same to occur on PY2.
     """
-    textual_output = _force_default_coding(string_or_bytes, STR_KIND)
     if PY2:
         # Simulate decoding done by PY3 to trigger identical exceptions
         # note the use of a forced "utf8" encoding value: this function
         # is generally used to wrap, for example, substitutions of values
         # into strings that are defined in the source code. In Python 3
         # these are mandated to be UTF-8, and thus decoding as "utf8" is
         # what will be attempted on supplied input. Match it.
-        codecs.decode(textual_output, "utf8")
+        textual_output = codecs.encode(string_or_bytes, 'utf8')
+    elif not _is_unicode(string_or_bytes):
+        textual_output = str(string_or_bytes, 'utf8')
+    else:
+        textual_output = string_or_bytes
     return textual_output

tests/test_mig_shared_compat.py

@@ -33,21 +33,31 @@
 sys.path.append(os.path.realpath(os.path.join(os.path.dirname(__file__), ".")))
 from support import MigTestCase, testmain
 
-from mig.shared.compat import ensure_native_string
+from mig.shared.compat import PY2, ensure_native_string
 
 DUMMY_BYTECHARS = b'DEADBEEF'
 DUMMY_BYTESRAW = binascii.unhexlify('DEADBEEF') # 4 bytes
+DUMMY_UNICODE = u'UniCode123½¾µßðþđŋħĸþł@ª€£$¥©®'
 
 class MigSharedCompat__ensure_native_string(MigTestCase):
     # TODO: Add docstrings to this class and its methods
     def test_char_bytes_conversion(self):
         actual = ensure_native_string(DUMMY_BYTECHARS)
+        self.assertIs(type(actual), str)
         self.assertEqual(actual, 'DEADBEEF')
 
     def test_raw_bytes_conversion(self):
         with self.assertRaises(UnicodeDecodeError):
             ensure_native_string(DUMMY_BYTESRAW)
 
+    def test_unicode_conversion(self):
+        actual = ensure_native_string(DUMMY_UNICODE)
+        self.assertEqual(type(actual), str)
+        if PY2:
+            self.assertEqual(actual, DUMMY_UNICODE.encode("utf8"))
+        else:
+            self.assertEqual(actual, DUMMY_UNICODE)
+
 
 if __name__ == '__main__':
     testmain()