Fix test coverage.
Fix test coverage.

deeplycloudy/MetPy,ahaberlie/MetPy,jrleeman/MetPy,ShawnMurd/MetPy,ahaberlie/MetPy,dopplershift/MetPy,Unidata/MetPy,dopplershift/MetPy,Unidata/MetPy,jrleeman/MetPy,ahill818/MetPy