The basic problem here is that jmock-junit4 happens to drag in junit-dep 4.4, and this is leading to a conflict with junit. Normally, Gradle's conflict resolution ensures that exactly one version of a dependency ends up in a classpath, but in this case, Gradle has no way of knowing that junit and junit-dep happen to include the same classes. And so, they are both included in the classpath.

This happens to work with Gradle 0.8, because it adds inherited dependencies to a classpath before the direct dependencies, and so junit ends up in the classpath before junit-dep. In 0.9, this order has been swapped, so that inherited dependencies are added after the direct dependencies, and so junit-dep ends up in the classpath before junit and the tests fail.

I think the real problem here is that there is no way to specify that junit implies junit-dep (particularly given that the dependency meta-data happens to come from a pom.xml in maven central) so that Gradle conflict resolution can figure out that it only needs to include junit.

Another work around is to exclude junit-dep from the dependencies of jmock_junit4:

dependencies {
    testCompile (jmock_junit4) { exclude name: 'junit-dep' }
}

We will address this problem as part of GRADLE-1037.