when:
        def set = snapshot(existing, missing)
        then:
        assertFileSnapshot(set, existing)
        assertMissingFileSnapshot(set, missing)
        assertMissingFileSnapshot(set, existing.file("some/sub/path"))
        assertMissingFileSnapshot(set, missing.file("some/sub/path"))
    }

    def "can invalidate paths"() {
        def parent = tmpDir.createDir()