Improve tests.
Improve tests.

jcrist/dask,mikegraham/dask,marianotepper/dask,hainm/dask,hainm/dask,chrisbarber/dask,simudream/dask,jayhetee/dask,gameduell/dask,ssanderson/dask,freeman-lab/dask,wiso/dask,jakirkham/dask,wiso/dask,vikhyat/dask,mraspaud/dask,PhE/dask,clarkfitzg/dask,simudream/dask,blaze/dask,ContinuumIO/dask,mrocklin/dask,PhE/dask,vikhyat/dask,ssanderson/dask,dask/dask,cpcloud/dask,mraspaud/dask,jayhetee/dask,pombredanne/dask,jakirkham/dask,marianotepper/dask,clarkfitzg/dask,mrocklin/dask,pombredanne/dask,jcrist/dask,ContinuumIO/dask,freeman-lab/dask,dask/dask,blaze/dask,cowlicks/dask