     let image = helper.image
     let key = "http://\(#function)"
     
-    waitUntil { done in
+    waitUntil(timeout: 5) { done in
       cache.store(image, forKey: key) {
         cache.retrieveImage(forKey: key) { image, type in
           expect(image).toNot(beNil())

    let cache = Cache(name: "mock", backingStore: MockStore())
    let image = helper.image

    waitUntil { done in
      cache.store(image, forKey: "key1") {
        cache.retrieveImage(forKey: "key2") { image, type in
          expect(image).to(beNil())

    let image = helper.image
    let key = #function

    waitUntil(timeout: 5) { done in
      mockCache.store(image, forKey: key) {
        namedCache.retrieveImage(forKey: key, completion: { image, _ in
          expect(image).to(beNil())
