cacher: decrease the running time of TestConsistentReadFallback

Author: p0lyn0mial

staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher_whitebox_test.go

@@ -435,17 +435,15 @@ apiserver_watch_cache_consistent_read_total{fallback="true", resource="pods", su
 				podList.ResourceVersion = tc.watchCacheRV
 				return nil
 			}
-			// TODO: Use fake clock for this test to reduce execution time.
-			cacher, _, err := newTestCacher(backingStorage)
+			c := testingclock.NewFakeClock(time.Now())
+			cacher, _, err := newTestCacherWithoutSyncing(backingStorage, c)
 			if err != nil {
 				t.Fatalf("Couldn't create cacher: %v", err)
 			}
 			defer cacher.Stop()
 			proxy := NewCacheProxy(cacher, backingStorage)
-			if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
-				if err := cacher.ready.wait(context.Background()); err != nil {
-					t.Fatalf("unexpected error waiting for the cache to be ready")
-				}
+			if err := cacher.ready.wait(context.Background()); err != nil {
+				t.Fatalf("unexpected error waiting for the cache to be ready")
 			}
 
 			if fmt.Sprintf("%d", cacher.watchCache.resourceVersion) != tc.watchCacheRV {
@@ -466,8 +464,28 @@ apiserver_watch_cache_consistent_read_total{fallback="true", resource="pods", su
 				return nil
 			}
 			result := &example.PodList{}
+
+			ctx, clockStepCancelFn := context.WithTimeout(context.TODO(), time.Minute)
+			defer clockStepCancelFn()
+			if tc.expectBlock {
+				go func(ctx context.Context) {
+					for {
+						select {
+						case <-ctx.Done():
+							return
+						default:
+							if c.HasWaiters() {
+								c.Step(blockTimeout)
+							}
+							time.Sleep(time.Millisecond)
+						}
+					}
+				}(ctx)
+			}
+
 			start := cacher.clock.Now()
 			err = proxy.GetList(context.TODO(), "pods/ns", storage.ListOptions{ResourceVersion: ""}, result)
+			clockStepCancelFn()
 			duration := cacher.clock.Since(start)
 			if (err != nil) != tc.expectError {
 				t.Fatalf("Unexpected error err: %v", err)