chore: add more tests (#3261)

core/prof/runtime.go

@@ -2,6 +2,8 @@ package prof
 
 import (
 	"fmt"
+	"io"
+	"os"
 	"runtime"
 	"time"
 )
@@ -13,6 +15,10 @@ const (
 
 // DisplayStats prints the goroutine, memory, GC stats with given interval, default to 5 seconds.
 func DisplayStats(interval ...time.Duration) {
+	displayStatsWithWriter(os.Stdout, interval...)
+}
+
+func displayStatsWithWriter(writer io.Writer, interval ...time.Duration) {
 	duration := defaultInterval
 	for _, val := range interval {
 		duration = val
@@ -24,7 +30,7 @@ func DisplayStats(interval ...time.Duration) {
 		for range ticker.C {
 			var m runtime.MemStats
 			runtime.ReadMemStats(&m)
-			fmt.Printf("Goroutines: %d, Alloc: %vm, TotalAlloc: %vm, Sys: %vm, NumGC: %v\n",
+			fmt.Fprintf(writer, "Goroutines: %d, Alloc: %vm, TotalAlloc: %vm, Sys: %vm, NumGC: %v\n",
 				runtime.NumGoroutine(), m.Alloc/mega, m.TotalAlloc/mega, m.Sys/mega, m.NumGC)
 		}
 	}()