Currently since there are no UI tests for the ImageGraph plugin, changes have to be tested manually. This is time consuming, and since we have a way to invoke the plugin and take screenshots, it is also unnecessary.

Creating screenshot tests for ImageGraph that pass on different machines may not be possible since the plugin uses the gd PHP extension, but with screenshot tests we can at least automate the instrumentation. So when testing, we don't have to manually invoke ImageGraph, we can just run the test and look at the output to make sure everything's kosher.