feat(Go-StudyExample):2020/12/31：新增【Go每日一库】go-cmp结构体比较工具

example/go-cmp/Transformer_test.go

@@ -0,0 +1,75 @@
+/*
+ *  @Author : huangzj
+ *  @Time : 2020/12/31 14:33
+ *  @Description： 比较的时候转换对应的属性，改变结构体对比的规则
+ */
+
+package go_cmp
+
+import (
+	"fmt"
+	"github.com/google/go-cmp/cmp"
+	"testing"
+)
+
+type UserO struct {
+	Name string
+	Age  int
+}
+
+func omitAge(u UserO) string {
+	return u.Name
+}
+
+type UserO2 struct {
+	Name    string
+	Age     int
+	Email   string
+	Address string
+}
+
+func omitAge2(u UserO2) UserO2 {
+	return UserO2{u.Name, 0, u.Email, u.Address}
+}
+
+//对某个字段忽略比较，也就是返回字段默认值
+func TestOmit(t *testing.T) {
+	u1 := UserO{Name: "dj", Age: 18}
+	u2 := UserO{Name: "dj", Age: 28}
+
+	//i think 这边omitAge只返回name属性应该是值比较UserO的name属性即可
+	fmt.Println("u1 equals u2?", cmp.Equal(u1, u2, cmp.Transformer("omitAge", omitAge)))
+
+	u3 := UserO2{Name: "dj", Age: 18, Email: "dj@example.com"}
+	u4 := UserO2{Name: "dj", Age: 28, Email: "dj@example.com"}
+
+	u5 := UserO2{Name: "dj", Age: 18, Email: "dj@example.com"}
+	u6 := UserO2{Name: "dj1", Age: 28, Email: "dj@example.com"}
+
+	//i think 这边的omitAge2返回修改之后的UserO2,只把age设置为0，其他属性不变，说明还是会参与到比较
+	fmt.Println("u3 equals u4?", cmp.Equal(u3, u4, cmp.Transformer("omitAge", omitAge2)))
+
+	fmt.Println("u5 equals u5?", cmp.Equal(u5, u6, cmp.Transformer("omitAge", omitAge2)))
+}
+
+type NetAddrO struct {
+	IP   string
+	Port int
+}
+
+func transformLocalhost(a NetAddrO) NetAddrO {
+	if a.IP == "localhost" {
+		return NetAddrO{IP: "127.0.0.1", Port: a.Port}
+	}
+
+	return a
+}
+
+//对结构体进行对比的时候，修改某字段的值
+func TestTransformValue(t *testing.T) {
+	a1 := NetAddrO{"127.0.0.1", 5000}
+	a2 := NetAddrO{"localhost", 5000}
+
+	//这边是把NetAddr对应的IP进行转换，localhost == 127.0.0.1 所以直接进行转换，比较的结果就会一致
+	fmt.Println("a1 equals a2?", cmp.Equal(a1, a2, cmp.Transformer("localhost", transformLocalhost)))
+}