Add unittests

[danielcdh]

When we open-sourced this tool, the tests are omitted because it'll introduce another dependency to gtest. But it's worth the effort to add the test to this package too to track regression.

[danielcdh]

Diego, I remember you showed interests in open-sourcing tests for this. Shall I assign this issue to you?

Thanks,
Dehao

[dnovillo]

On Wed, Apr 23, 2014 at 3:54 PM, Dehao Chen notifications@github.comwrote:

Diego, I remember you showed interests in open-sourcing tests for this.
Shall I assign this issue to you?

Sure. I can't give it high priority for a while, though.

Diego.