Refactor mock Sleep, add mock Now time function

Instead of the Sleep function pointer being a standalong global
variable, move it into a new Time struct, and add a Now function
pointer, so that time.Now() can be mocked. Time.Now() isn't used yet.
This will be cleaner if we need to mock more time-related functions in
the future.

cmd/root.go

@@ -381,8 +381,9 @@ func init() {
 
 	logrus.RegisterExitHandler(onexit)
 
-	// Indirect function for test mocking (so unit tests can talk to stub functions)
-	common.Sleep = time.Sleep
+	// Indirect functions for test mocking (so unit tests can talk to stub functions)
+	common.Time.Sleep = time.Sleep
+	common.Time.Now = time.Now
 }
 
 // initConfig reads in config file and ENV variables if set.

common/common.go

@@ -53,10 +53,16 @@ type Options struct {
 // in unit tests it points to a function to mock RPCs to zcashd.
 var RawRequest func(method string, params []json.RawMessage) (json.RawMessage, error)
 
-// Sleep allows a request to time.Sleep() to be mocked for testing;
-// in production, it points to the standard library time.Sleep();
-// in unit tests it points to a mock function.
-var Sleep func(d time.Duration)
+// Time allows time-related functions to be mocked for testing,
+// so that tests can be deterministic and so they don't require
+// real time to elapse. In production, these point to the standard
+// library `time` functions; in unit tests they point to mock
+// functions (set by the specific test as required).
+// More functions can be added later.
+var Time struct {
+	Sleep func(d time.Duration)
+	Now   func() time.Time
+}
 
 // Log as a global variable simplifies logging
 var Log *logrus.Entry
@@ -163,7 +169,7 @@ func FirstRPC() {
 			"error": rpcErr.Error(),
 			"retry": retryCount,
 		}).Warn("error with getblockchaininfo rpc, retrying...")
-		Sleep(time.Duration(10+retryCount*5) * time.Second) // backoff
+		Time.Sleep(time.Duration(10+retryCount*5) * time.Second) // backoff
 	}
 }
 
@@ -312,7 +318,7 @@ func BlockIngestor(c *BlockCache, rep int) {
 			}
 			// Delay then retry the same height.
 			c.Sync()
-			Sleep(10 * time.Second)
+			Time.Sleep(10 * time.Second)
 			wait = true
 			continue
 		}
@@ -323,7 +329,7 @@ func BlockIngestor(c *BlockCache, rep int) {
 				Log.Info("Waiting for zcashd height to reach Sapling activation height ",
 					"(", c.GetFirstHeight(), ")...")
 				reorgCount = 0
-				Sleep(20 * time.Second)
+				Time.Sleep(20 * time.Second)
 				continue
 			}
 			if wait {
@@ -333,7 +339,7 @@ func BlockIngestor(c *BlockCache, rep int) {
 					Log.Info("Ingestor waiting for block: ", height)
 					lastHeightLogged = height - 1
 				}
-				Sleep(2 * time.Second)
+				Time.Sleep(2 * time.Second)
 				wait = false
 				continue
 			}

common/common_test.go

@@ -77,6 +77,10 @@ func sleepStub(d time.Duration) {
 	sleepCount++
 	sleepDuration += d
 }
+func nowStub() time.Time {
+	start := time.Time{}
+	return start.Add(sleepDuration)
+}
 
 // ------------------------------------------ GetLightdInfo()
 
@@ -110,7 +114,7 @@ func getLightdInfoStub(method string, params []json.RawMessage) (json.RawMessage
 func TestGetLightdInfo(t *testing.T) {
 	testT = t
 	RawRequest = getLightdInfoStub
-	Sleep = sleepStub
+	Time.Sleep = sleepStub
 	// This calls the getblockchaininfo rpc just to establish connectivity with zcashd
 	FirstRPC()
 
@@ -270,7 +274,7 @@ func getblockStub(method string, params []json.RawMessage) (json.RawMessage, err
 func TestBlockIngestor(t *testing.T) {
 	testT = t
 	RawRequest = getblockStub
-	Sleep = sleepStub
+	Time.Sleep = sleepStub
 	os.RemoveAll(unitTestPath)
 	testcache := NewBlockCache(unitTestPath, unitTestChain, 380640, false)
 	BlockIngestor(testcache, 11)

common/mempool.go

@@ -64,7 +64,7 @@ func GetMempool(sendToClient func(*walletrpc.RawTransaction) error) error {
 				g_lock.Unlock()
 				return err
 			}
-			g_lastTime = time.Now()
+			g_lastTime = Time.Now()
 		}
 		// Send transactions we haven't sent yet, best to not do so while
 		// holding the mutex, since this call may get flow-controlled.
@@ -76,7 +76,7 @@ func GetMempool(sendToClient func(*walletrpc.RawTransaction) error) error {
 				return err
 			}
 		}
-		time.Sleep(200 * time.Millisecond)
+		Time.Sleep(200 * time.Millisecond)
 		g_lock.Lock()
 		if g_lastBlockChainInfo.BestBlockHash != stayHash {
 			break