Unable to mock variadic function with function argument

[BeyondEvil]

I have a function with this signature:

func (api *Client) PostMessage(channelID string, options ...MsgOption) (string, string, error)`

Where MsgOption is a function-type:

type MsgOption func(*sendConfig) error

The mock:

func (mock *slackAPIMock) PostMessage(channelID string, options ...slack.MsgOption) (string, string, error) {
	args := mock.Called(channelID, options)
	return args.String(0), args.String(1), args.Error(2)
}

Turning it On:

	options := []slack.MsgOption{
		slack.MsgOptionAttachments(expectedAttachment),
		slack.MsgOptionAsUser(true),
	}

	mock.On(
		"PostMessage",
		mock.AnythingOfTypeArgument("string"),
		options,
	).Return(mockedChannel, timestamp, nil)

And the assert:

	mock.AssertCalled(
		t,
		"PostMessage",
		mockedChannel,
		slack.MsgOptionAttachments(expectedAttachment),
		slack.MsgOptionAsUser(true),
	)

Result:

Diff: 1: FAIL:  ([]slack.MsgOption=[0x1376370 0x1376180]) != ([]slack.MsgOption=[0x1376370 0x1376180])

They look the same to me. What am I missing here? 🤔

Full output

panic: 

mock: Unexpected Method Call
-----------------------------

PostMessage(string,[]slack.MsgOption)
		0: "some_channel"
		1: []slack.MsgOption{(slack.MsgOption)(0x1376370), (slack.MsgOption)(0x1376180)}

The closest call I have is: 

PostMessage(mock.AnythingOfTypeArgument,[]slack.MsgOption)
		0: "string"
		1: []slack.MsgOption{(slack.MsgOption)(0x1376370), (slack.MsgOption)(0x1376180)}


Diff: 1: FAIL:  ([]slack.MsgOption=[0x1376370 0x1376180]) != ([]slack.MsgOption=[0x1376370 0x1376180]) [recovered]
	panic: 

mock: Unexpected Method Call
-----------------------------

PostMessage(string,[]slack.MsgOption)
		0: "some_channel"
		1: []slack.MsgOption{(slack.MsgOption)(0x1376370), (slack.MsgOption)(0x1376180)}

The closest call I have is: 

PostMessage(mock.AnythingOfTypeArgument,[]slack.MsgOption)
		0: "string"
		1: []slack.MsgOption{(slack.MsgOption)(0x1376370), (slack.MsgOption)(0x1376180)}


Diff: 1: FAIL:  ([]slack.MsgOption=[0x1376370 0x1376180]) != ([]slack.MsgOption=[0x1376370 0x1376180])

[proclaim]

I think this is a gotcha pitfall. Although you see this message: ([]slack.MsgOption=[0x1376370 0x1376180]) != ([]slack.MsgOption=[0x1376370 0x1376180]) and sure from the visual it's the same, but if you think, we're actually comparing 2 different thing, they just have the same value. (you can only compare primative type)

let me explain:
in the postMessage (small p) you accept the message, and you construct the attachment and pass that attachment to PostMessage (cap P), and when you mock the PostMessage it's comparing the created attachment, with the expectedAttachment and although they have the same value, it's different to go

so if you change line 34, from options to mock.Anything it should work.
here's what worked for me (I did remove some irrelevant code)

func TestPostMessage(t *testing.T) {
	setSlackChannel(mockedChannel)

	expectedColor := "good"
	expectedMessage := "test message"
	// expectedAttachment := slack.Attachment{
	// 	Color:    expectedColor,
	// 	Fallback: expectedMessage,
	// 	Text:     expectedMessage,
	// }

	setColor(expectedColor)

	// options := []slack.MsgOption{
	// 	slack.MsgOptionAttachments(expectedAttachment),
	// 	slack.MsgOptionAsUser(true),
	// }
	timestamp := "123456"
	mockAPI := proxySlackAPIMock{}
	mockAPI.On(
		"PostMessage",
		mock.AnythingOfTypeArgument("string"),
		mock.Anything,
	).Return(mockedChannel, timestamp, nil)

	assert.Nil(t, postMessage(&mockAPI, expectedMessage))

	mockAPI.AssertExpectations(t)
	mockAPI.AssertNumberOfCalls(t, "PostMessage", 1)
	// mockAPI.AssertCalled(
	// 	t,
	// 	"PostMessage",
	// 	mockedChannel,
	// 	mock.Anything,
	// 	slack.MsgOptionAsUser(true),
	// )
}

[BeyondEvil]

Sure, that will make the test pass @proclaim but it also then doesn't assert that PostMessage was called with the expected attachment. That is, it diminishes the test a bit.

I think the main problem is that the slack.MsgOption* functions returns another function.

[gavwu]

the go said:

...
//
// Func values are deeply equal if both are nil; otherwise they are not deeply equal.
...
func DeepEqual(x, y interface{}) bool {

[gavwu]

the go said:

...
//
// Func values are deeply equal if both are nil; otherwise they are not deeply equal.
...
func DeepEqual(x, y interface{}) bool {

and mock use the function to test if they are equal