test: add benchmark (#3)

README.md

@@ -52,5 +52,22 @@ func main() {
 
 ```
 
+## Benchmark
+
+```sh
+go test -bench=. -run=xxx -benchmem
+```
+
+The benchmark result on my Macbook M3 Pro:
+
+    goos: darwin
+    goarch: arm64
+    pkg: github.com/hoanguyenkh/promise4g
+    cpu: Apple M3 Pro
+    BenchmarkNewWithPool/default-11                   892462              1331 ns/op             352 B/op          8 allocs/op
+    BenchmarkNewWithPool/conc-11                      903475              1289 ns/op             352 B/op          8 allocs/op
+    BenchmarkNewWithPool/ants-11                      951216              1296 ns/op             352 B/op          8 allocs/op
+
+
 ## Referer
  1) https://github.com/chebyrash/promise

promise_test.go

@@ -318,3 +318,46 @@ func TestCheckAllConcurrent(t *testing.T) {
 	require.Equal(t, []string{"one", "two", "three"}, results)
 	require.Less(t, elapsed, 350*time.Millisecond, "Promises did not run concurrently")
 }
+
+func BenchmarkNewWithPool(b *testing.B) {
+	ctx := context.Background()
+
+	tests := []struct {
+		name string
+		pool Pool
+	}{
+		{
+			name: "default",
+			pool: newDefaultPool(),
+		},
+		{
+			name: "conc",
+			pool: func() Pool {
+				return FromConcPool(conc.New())
+			}(),
+		},
+		{
+			name: "ants",
+			pool: func() Pool {
+				antsPool, err := ants.NewPool(0)
+				require.NoError(b, err)
+				return FromAntsPool(antsPool)
+			}(),
+		},
+	}
+
+	for _, test := range tests {
+		b.Run(test.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				p := NewWithPool(ctx, func(resolve func(string), reject func(error)) {
+					resolve(test.name)
+				}, test.pool)
+
+				val, err := p.Await(ctx)
+				require.NoError(b, err)
+				require.NotNil(b, val)
+				require.Equal(b, test.name, val)
+			}
+		})
+	}
+}