add OnOverwrite function

[sunhao1256]

Summary

when mock repeate regist duplicate method name and arguments ，only return this first arguments , i want supply "OnOverwrite" function to overwrite the old regist which has been registed

Changes

mock.go add "Off" function

a := "xx"

d.Mock.On("hello", a).Return("xx1")
d.Mock.On("hello", a).Return("xx2")
get := d.Mock.MethodCalled("hello", a).Get(0) //return xx1
fmt.Println(get)

d.Mock.On("hello", a).Return("xx1")
d.Mock.Off("hello", a)
d.Mock.On("hello", a).Return("xx2")
get := d.Mock.MethodCalled("hello", a).Get(0) //return xx2
fmt.Println(get)

Motivation

we need off function

Related issues

#558
#166

[boyan-soubachov]

Is there a need for this if we implement the .Unset()/.Off() function mentioned in #558 ? I'd rather prioritise getting #558 implemented first.

[sunhao1256]

Is there a need for this if we implement the .Unset()/.Off() function mentioned in #558 ? I'd rather prioritise getting #558 implemented first.

i modify OnOverwrite function to Off function , please review

[boyan-soubachov]

This isn't doing what #982 is doing though. We just need to agree/change the function naming in #982 and merge it.