reuse cluster for TFsShellTest and made each test isolated

Cut TFsShellTest from 6 minutes to 30 seconds.  Same trick can be used for all long running tests.
Final null means you can't assign it to a value
On Dec 21, 2014 11:29 AM, "Haoyuan Li" <notifications@github.com> wrote:

> In core/src/test/java/tachyon/client/FileInStreamTest.java
> <https://github.com/amplab/tachyon/pull/570#discussion-diff-22149624>:
>
> > @@ -36,26 +36,26 @@
> >    private static final int MEAN = (MIN_LEN + MAX_LEN) / 2;
> >    private static final int DELTA = 33;
> >
> > -  private LocalTachyonCluster mLocalTachyonCluster = null;
> > -  private TachyonFS mTfs = null;
> > +  private static LocalTachyonCluster CLUSTER = null;
>
> I'm confused. The following is not allowed?
> private static final LocalTachyonCluster CLUSTER = null;
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/amplab/tachyon/pull/570/files#r22149624>.
>