Add assert_greater compatibility function.

Fix tests to work with nose < 1.1.3. Compatibility functions borrowed from scikit-learn.

skimage/_shared/testing.py

@@ -0,0 +1,28 @@
+"""Testing utilities."""
+
+# Copyright (c) 2011 Pietro Berkes
+# License: Simplified BSD
+
+def _assert_less(a, b, msg=None):
+    message = "%r is not lower than %r" % (a, b)
+    if msg is not None:
+        message += ": " + msg
+    assert a < b, message
+
+
+def _assert_greater(a, b, msg=None):
+    message = "%r is not greater than %r" % (a, b)
+    if msg is not None:
+        message += ": " + msg
+    assert a > b, message
+
+
+try:
+    from nose.tools import assert_less
+except ImportError:
+    assert_less = _assert_less
+
+try:
+    from nose.tools import assert_greater
+except ImportError:
+    assert_greater = _assert_greater