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.
The rule is that constants are all caps. In this context this field is a
constant; it's only the framework that forces this to not be final.
On Dec 21, 2014 11:13 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-22149522>:
>
> > @@ -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;
>
> Should this be named as sCluster?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/amplab/tachyon/pull/570/files#r22149522>.
>