added failing test for narrow python builds, closes #456

test/test_wide_python.py

@@ -0,0 +1,14 @@
+
+def test_wide_python_build():
+    """This test is meant to fail on narrow python builds (common on Mac OS X).
+
+    See https://github.com/RDFLib/rdflib/issues/456 for more information.
+    """
+    assert len(u'\U0010FFFF') == 1, (
+        'You are using a narrow Python build!\n'
+        'This means that your Python does not properly support chars > 16bit.\n'
+        'On your system chars like c=u"\\U0010FFFF" will have a len(c)==2.\n'
+        'As this can cause hard to debug problems with string processing\n'
+        '(slicing, regexp, ...) later on, we strongly advise to use a wide\n'
+        'Python build in production systems.'
+    )