When running nosetests, raise exceptions for arithmetic errors.

nosetests will invoke the functions setup_module() and
teardown_module(), if defined, before and after running all test cases
within the module.

In general, numpy arithmetic errors (e.g. integer or floating-point
overflow, or division by zero) should not happen under normal
circumstances, and the package should neither assume that these errors
will raise an exception, nor assume that they won't.  Therefore, while
running the test suite, set the numpy error handling mode to "raise"
so the test will fail if such an error occurs.

Author: Benjamin Moody

tests/__init__.py

@@ -0,0 +1,16 @@
+import numpy as np
+
+
+_np_error_state = {}
+
+
+def setup_module():
+    # Raise exceptions for arithmetic errors, except underflow
+    global _np_error_state
+    _np_error_state = np.seterr()
+    np.seterr('raise', under='ignore')
+
+
+def teardown_module():
+    # Restore original error handling state
+    np.seterr(**_np_error_state)