GradleRunner is not executing my plugins in a way that works

Here’s the test run

I realize it’s not particularly enlightening… if I tack a version on my plugin bundle and building from the test directory works fine…

com.xenoterracide.gradle.plugin.WorkingProjectTest > build() FAILED
    org.gradle.testkit.runner.UnexpectedBuildFailure at

Unexpected build execution failure in /tmp/junit3306043908619773069/junit1361722169744298414 with arguments [build]

> Task :compileJava
> Task :processResources NO-SOURCE
> Task :classes
> Task :jar
> Task :assemble
> Task :checkstyleMain FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':checkstyleMain'.
> groovy/util/AntBuilder

how should I improve my test such that it works?