fix the external scaler error when minAvailable is 0 (#227)

Signed-off-by: ChrisLiu <chrisliu1995@163.com>

pkg/externalscaler/externalscaler.go

@@ -197,7 +197,7 @@ func handleMinNum(totalNum, noneNum int, minNumStr string) (int, error) {
 		delta = math.Round(delta*100) / 100
 		minNum := int(math.Ceil(delta)) + noneNum
 		return minNum, nil
-	case n >= 1:
+	case n >= 1 || n == 0:
 		n = math.Ceil(n)
 		return int(n), nil
 	}

pkg/externalscaler/externalscaler_test.go

@@ -102,7 +102,7 @@ func TestHandleMinNum(t *testing.T) {
 			noneNum:   2,
 			minNumStr: "0",
 			wantMin:   0,
-			wantErr:   true,
+			wantErr:   false,
 		},
 		{
 			name:      "invalid n - negative",