def "the empty hierarchy has no values"() {
        def emptyHierarchy = emptyHierarchy()

        expect:
        emptyHierarchy.empty
        getAllValues(emptyHierarchy).empty
        getValuesFor(emptyHierarchy, "/some/location").empty
    }

    def "non-empty hierarchies are not-empty"() {
        def hierarchy = emptyHierarchy()
        hierarchy = hierarchy.recordValue(VfsRelativePath.of(location), 1)