UI Indexing flow should be tested

There is already a test that tests the indexing logic but it works as follows:

Select items to index
Check how many remaining
Call $index->index()
Check how many remaining
Check if there are no more remaining

We could use a test that clicks the indexing button also. Any idea/suggestions as to batch processes to be tested properly?

Committed http://drupalcode.org/sandbox/daeron/2091893.git/commit/0580fa5