英文:
how to compare funcs in golang
问题
我正在尝试为我的包编写一个测试，但在比较函数时失败了。以下是我实际在做的事情：
package main
import (
"fmt"
"reflect"
)
type HandlerFunc func(cmd interface{})
type Bus struct {
handlers map[reflect.Type]HandlerFunc
}
func (bus *Bus) RegisterHandler(cmd interface{}, handler HandlerFunc) {
bus.handlers[reflect.TypeOf(cmd)] = handler
}
func (bus *Bus) GetHandler(cmd interface{}) HandlerFunc {
t := reflect.TypeOf(cmd)
for kind, handler := range bus.handlers {
if t == kind {
return handler
}
}
return nil
}
func New() *Bus {
return &Bus{
handlers: make(map[reflect.Type]HandlerFunc),
}
}
type RegisterUserCommand struct {}
func main() {
bus := New()
handler := func (cmd interface{}) {}
bus.RegisterHandler(&RegisterUserCommand{}, handler)
retrieved := bus.GetHandler(&RegisterUserCommand{})
if retrieved != handler {
fmt.Println("Not the same!")
return
}
fmt.Println("Same!")
}
将retrieved与handler进行比较会导致以下错误：
invalid operation: (func(interface {}))(retrieved) != handler (func can only be compared to nil)
如何正确测试我检索到的函数与之前添加的函数是相同的？
英文:
I'm attempting write a test for my package and failing at comparing funcs. Here's essentially what i'm doing.
package main
import (
"fmt"
"reflect"
)
type HandlerFunc func(cmd interface{})
type Bus struct {
handlers map[reflect.Type]HandlerFunc
}
func (bus *Bus) RegisterHandler(cmd interface{}, handler HandlerFunc) {
bus.handlers[reflect.TypeOf(cmd)] = handler
}
func (bus *Bus) GetHandler(cmd interface{}) HandlerFunc {
t := reflect.TypeOf(cmd)
for kind, handler := range bus.handlers {
if t == kind {
return handler
}
}
return nil
}
func New() *Bus {
return &Bus{
handlers: make(map[reflect.Type]HandlerFunc),
}
}
type RegisterUserCommand struct {}
func main() {
bus := New()
handler := func (cmd interface{}) {}
bus.RegisterHandler(&RegisterUserCommand{}, handler)
retrieved := bus.GetHandler(&RegisterUserCommand{})
if retrieved != handler {
fmt.Println("Not the same!")
return
}
fmt.Println("Same!")
}
Comparing retrieved with handler causes the following error
invalid operation: (func(interface {}))(retrieved) != handler (func can only be compared to nil)
How can i properly test the function i'm retrieving is the same one added previously?
答案1
得分: 4
鉴于您无法比较函数，您可以以不同的方式编写测试。您可以让handler在测试中设置一个布尔值，并通过调用它并检查布尔值是否更改来检查是否获得了正确的函数。
以下是一个示例：
func main() {
bus := New()
called := false
handler := func (cmd interface{}) { called = true }
bus.RegisterHandler(&RegisterUserCommand{}, handler)
bus.GetHandler(&RegisterUserCommand{})(nil)
if called {
fmt.Println("我们得到了正确的处理程序！")
return
}
fmt.Println("我们没有得到正确的处理程序")
}
英文:
Given that you can't compare functions, you can write your test in a different way. You can make handler set a boolean value in your test and check that you've got the right function by calling it and seeing if the boolean changes.
Here's an example:
func main() {
bus := New()
called := false
handler := func (cmd interface{}) { called = true }
bus.RegisterHandler(&RegisterUserCommand{}, handler)
bus.GetHandler(&RegisterUserCommand{})(nil)
if called {
fmt.Println("We got the right handler!")
return
}
fmt.Println("We didn't get the right handler")
}
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