Merging Sessions with EclEmma

A subtle feature of EclEmma that I didn't notice yesterday is the ability to merge sessions.

While this certainly has application in areas where multiple test runs, suites or executions are responsible for some indication of 'total coverage', that aspect wasn't particularly exciting to me.

What I didn't realize is that this lets you merge in changes in coverage with a previous high-level coverage run. For instance. A test suite that I ran yesterday out of curiosity took 35 minutes to run through EclEmma.

Since that time, I improved the coverage of a few classes just to see the results. I can and did run a coverage test against those few individual tests just to verify that the coverage was as expected, but only this morning did I realize that I could merge those individual test runs back into the overall suite.

This allows me to get a decent 'update' of the overall coverage without running the whole suite again. Useful.

Eclipse Code Coverage with EclEmma

It's really great to see (via the Eclipse Awards) that someone has taken the time to integrate a free coverage tool with Eclipse: EclEmma.

I've used Emma before, but hadn't followed the recent development that sees it well-integrated with the IDE. Frankly, this was the one thing that really made the commercial offerings (e.g. Clover) attractive still, so now that Emma has taken this step, there's less reason to look elsewhere.

This, to me, feels like a great model for addressing test coverage -- right in the tool you use to write the code and the unit tests. Gives you a great capability to write tests, check coverage, and write a bit more.

Even more impressive, it seems as if EclEmma can also support loading coverage results from an external launch. So, for instance, if your nightly build ran a long project-wide coverage with Emma, it seems as if you'd be able to take the results of that coverage run, fire up EclEmma and see the results.

I'll be testing this out soon.