diff --git a/tests/__init__.py b/tests/__init__.py
index 1d4d2e3d..663b89ec 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -22,3 +22,22 @@ def path_to_data_dir(name):
     path = os.path.abspath(path)
     return os.path.join(path, name)
 
+class IsA(object):
+    def __init__(self, klass):
+        self.klass = klass
+
+    def __eq__(self, rhs):
+        try:
+            return isinstance(rhs, self.klass)
+        except TypeError:
+            return type(rhs) == type(self.klass)
+
+    def __ne__(self, rhs):
+        return not self.__eq__(rhs)
+
+    def __repr__(self):
+        return str(self.klass)
+
+any_int = IsA(int)
+any_str = IsA(str)
+any_unicode = IsA(unicode)