The context is a multi-project build, I haven't checked if the same is true in a single project build.

If there is a dependency, for example:

dependencies { testCompile 'junit:junit:4.8.2' }

but there is no repository specification, for example:

repositories { mavenCentral ( ) }

then, even if the dependency is in the Gradle cash, the dependecy is not added to the classpath and there is no message of any sort indicating this. Even with -d there is no error message just impenetrable messages about Ivy resolution and some sort of null.