expect:
        set.sourceDirectories.toString() == '<display-name>'
        set.asFileTree.toString() == '<display-name>'
        set.matching {}.toString() == '<display-name>'
    }

    void isEmptyWhenNoSourceDirectoriesSpecified() {
        expect:
        set.empty
        set.files.empty
        set.sourceDirectories.empty
        set.srcDirs.empty
        set.srcDirTrees.empty
    }