So when I tested this I found that np.isfinite can return either TypeError or NotImplementedError, depending on the setup.  For example:
My machine (Python=2.7.6, numpy=1.8.0):
```
>>> np.isfinite([1, 'a'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Not implemented for this type
```
However, on the TravisCI box Python=2.6.9, numpy=1.5.1 this is actually a NotImplementedError.  How do I determine in the test which one is going to be raised?