Quite a bit of work on new public errors and their unit tests

tests/util.py

@@ -99,6 +99,14 @@ class ExceptionNotRaised(Exception):
         return self.msg % self.expected.__name__
 
 
+def assert_equal(val1, val2):
+    """
+    Assert ``val1`` and ``val2`` are the same type and of equal value.
+    """
+    assert type(val1) is type(val2), '%r != %r' % (val1, val2)
+    assert val1 == val2, '%r != %r' % (val1, val2)
+
+
 def raises(exception, callback, *args, **kw):
     """
     Tests that the expected exception is raised; raises ExceptionNotRaised