add unit test for pkg/pool/pool.go (#7152)

Signed-off-by: ZouYu <zouy.fnst@cn.fujitsu.com>

pkg/pool/pool_test.go

@@ -0,0 +1,78 @@
+// Copyright 2020 The Prometheus Authors
+// 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 pool
+
+import (
+	"testing"
+
+	"github.com/prometheus/prometheus/util/testutil"
+)
+
+func makeFunc(size int) interface{} {
+	return size
+}
+
+func TestGet(t *testing.T) {
+	testPool := New(1, 8, 2, makeFunc)
+	cases := []struct {
+		size     int
+		expected int
+	}{
+		{
+			size:     -1,
+			expected: 1,
+		},
+		{
+			size:     3,
+			expected: 4,
+		},
+		{
+			size:     10,
+			expected: 10,
+		},
+	}
+	for _, c := range cases {
+		ret := testPool.Get(c.size)
+		testutil.Equals(t, c.expected, ret)
+	}
+}
+
+func TestPut(t *testing.T) {
+	testPool := New(1, 8, 2, makeFunc)
+	cases := []struct {
+		slice    []int
+		size     int
+		expected interface{}
+	}{
+		{
+			slice:    make([]int, 1),
+			size:     1,
+			expected: []int{},
+		},
+		{
+			slice:    make([]int, 8),
+			size:     8,
+			expected: []int{},
+		},
+		{
+			slice:    nil,
+			size:     2,
+			expected: 2,
+		},
+	}
+	for _, c := range cases {
+		testPool.Put(c.slice)
+		testutil.Equals(t, c.expected, testPool.Get(c.size))
+	}
+}