fix golint issues

core/timex/relativetime_test.go

@@ -16,7 +16,7 @@ func TestRelativeTime(t *testing.T) {
 }
 
 func TestRelativeTime_Time(t *testing.T) {
-	diff := Time().Sub(time.Now())
+	diff := time.Until(Time())
 	if diff > 0 {
 		assert.True(t, diff < time.Second)
 	} else {

core/timex/ticker_test.go

@@ -27,12 +27,9 @@ func TestFakeTicker(t *testing.T) {
 
 	var count int32
 	go func() {
-		for {
-			select {
-			case <-ticker.Chan():
-				if atomic.AddInt32(&count, 1) == total {
-					ticker.Done()
-				}
+		for range ticker.Chan() {
+			if atomic.AddInt32(&count, 1) == total {
+				ticker.Done()
 			}
 		}
 	}()