feat: add Fastrand UnitTest

internal/runtimex/runtime_test.go

@@ -1,7 +1,36 @@
+// Copyright 2024 ByteDance Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package runtimex
 
 import "testing"
 
+func TestFastrand(t *testing.T) {
+	var isRandom bool
+	for i := 0; i < 3; i++ {
+		x := Fastrand()
+		y := Fastrand()
+		if x != y {
+			isRandom = true
+			break
+		}
+	}
+	if !isRandom {
+		t.Fatal("Invalid fastrand results")
+	}
+}
+
 func BenchmarkFastrand(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		Fastrand()