function call assertions

[umairx97]

Hi, So i've been using tape for quite some time now, both in my personal projects and companies, but I'm finding there's no way to write an assertion that checks if a function has been called as part of another function. or maybe I haven't just looked hard enough

example of what i'm trying to do

// Test file
const test = require('tape')
const someFile = require('./somefile')

test('Should call function Y as well', t => {
  const response = someFile.func1()
  t.ok(response)
  t.toHaveBeenCalled(someFile.func2)
})

// someFile.js
function func1 () {
  return func2()
}

function func2 () {
  return 2
}

so is there any recommended way to do this, or maybe there's an internal function i'm missing on

Appreciate the help

[umairx97]

Update: I just noticed this is a way to add assertions, if that's recommended how would I go about writing a toHaveBeenCalled assertion any examples would be great

original ticket this was commented on: #555

[ljharb]

In this case, you can't do it with tape as-is. You need an object mocking/spying library - which is what https://npmjs.com/sinon is for.

You can then make assertions about your sinon spies/mocks/stubs using tape.

[Raynos]

The alternative answer is that writing a test which checks what happens to the internals of a module is fragile and not a very useful test.

Your better of writing a test that checks the black box behavior of a module. Or changing the API of a module to make it easier to test.

If you want to write an assertion that a module for example does a logger.warn('oops', info) then passing in an instance of https://github.com/Raynos/testing-logger so that you can track and assert that the module does indeed emit useful log lines is a decent approach.

Changing the module would be something like someFile.func1(logger) or someFile.setLogger(logger)

[umairx97]

Thank you both @Raynos and @ljharb, both suggestions are good, but I think for my case sinon is a better choice