Wrote tests for the utils.go file (cadence-workflow#1385)

What changed?
Wrote tests for the utils.go file

Why?
Improve code coverage

How did you test it?

Potential risks

Author: jakobht

internal/common/util/util_test.go

@@ -0,0 +1,77 @@
+// Copyright (c) 2017-2021 Uber Technologies Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package util
+
+import (
+	"reflect"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_MergeDicts(t *testing.T) {
+	cases := []struct {
+		dic1     map[string]string
+		dic2     map[string]string
+		expected map[string]string
+	}{
+		{map[string]string{"a": "1", "b": "2"}, map[string]string{"b": "3", "c": "4"}, map[string]string{"a": "1", "b": "3", "c": "4"}},
+		{map[string]string{"a": "1"}, map[string]string{"a": "2"}, map[string]string{"a": "2"}},
+		{map[string]string{}, map[string]string{"a": "1"}, map[string]string{"a": "1"}},
+		{map[string]string{"a": "1"}, map[string]string{}, map[string]string{"a": "1"}},
+		{map[string]string{}, map[string]string{}, map[string]string{}},
+	}
+
+	for _, c := range cases {
+		result := MergeDicts(c.dic1, c.dic2)
+		assert.Equal(t, c.expected, result)
+	}
+}
+
+func Test_AwaitWaitGroup(t *testing.T) {
+	cases := []struct {
+		timeout  time.Duration
+		expected bool
+	}{
+		{10 * time.Millisecond, false},
+		{500 * time.Millisecond, true},
+	}
+
+	for _, c := range cases {
+		var wg sync.WaitGroup
+		wg.Add(1)
+
+		go func() {
+			time.Sleep(100 * time.Millisecond)
+			wg.Done()
+		}()
+
+		assert.Equal(t, c.expected, AwaitWaitGroup(&wg, c.timeout))
+	}
+}
+
+func Test_IsTypeByteSlice(t *testing.T) {
+	assert.True(t, IsTypeByteSlice(reflect.TypeOf([]byte(nil))))
+	assert.True(t, IsTypeByteSlice(reflect.PtrTo(reflect.TypeOf([]byte(nil)))))
+	assert.False(t, IsTypeByteSlice(reflect.TypeOf([]int(nil))))
+}