emock

Lightweight mocking library for function calls in Go

The purpose of this library is to allow easy mocking of function calls, and ease dependency injection.

Get it:

go get github.com/ebabani/emock

Docs

http://godoc.org/github.com/ebabani/emock

Mocking:

Example

The following example uses ginkgo and gomega for assertions

myFunc = func(a int, b string) string {
	return fmt.Sprintf("A IS %+v B is %+v", a, b)
}

It("should return an empty string", func() {
  mockObj = MockFunc(&myFunc) // (1)
  defer mockObj.Restore() // (2)
  
  ret := myFunc(123, "Cool stuff") // (3)
  
  Expect(mockObj.GetArgsForCall(0)).To(MatchArgs(123, "Cool stuff")) // (4)
  Expect(mockObj.CallCount()).To(Equal(1)) // (5)
  Expect(ret).To(BeEmpty()) // (6)
})

1 - Create a mock object

Mock a function at the given address, and return a mock object. The mock object can be used to check how many times the mocked function was called, and with what arguments. (See lines 4 and 5)

2 - Restore the original function implementation

Restore the function to its normal behaviour instead of the mock implemetation.

3 - Call the function.

When mocked, by default the function will return zero values, but you can also set custom return values.

4 - Check the args of the first call to myFunc.

GetArgsForCall(i) will return the args used in the i'th call to the mocked function. The args are returned as an []interface{}

MatchArgs is a custom gomega matcher to make it easier to check if the function was called with the right args.

5 Call count of the mocked function

How many times the mocked function was called.

6 Check the return value of the mocked function

By default when something is mocked it will return zero values for all its returns. (See https://golang.org/ref/spec#The_zero_value)

You can use mockObj.SetReturns to set custom returns, or mockObj.SetReturnFunc to replace the mocked function with another one with the same signature.