def e = thrown(IllegalArgumentException)
        e.message == "key cannot be null"
    }

    def "loads missing CachedArtifact from persistentIndexedCache"() {
        given:
        def key = createEntryInPersistentCache()
        _ * cachedArtifact.missing >> true

        when:
        def fromCache = index.lookup(key)

        then:
        fromCache == cachedArtifact
        fromCache.isMissing()
    }