Mocha: BeforeEach inside Describe

[heynemann]

I'm not sure if my case is actually a bug or if I'm not understanding correctly how to use beforeEach.

I have a common.js file with:

describe('API', function () {
  console.log("Common - Describe")
  beforeEach(async () => {
    console.log("Common - Before")
  })
})

Then in my test file I have:

require ('./common')

describe.only('API', function () {
  it('should do something', async () => {
    console.log("it")
  })
  // many more "it"s
})

I only get logs for "Common - Describe" and "it". The beforeEach never gets called.

Any ideas on what I'm doing wrong?

[ORESoftware]

Mocha uses a stack data structure to register all API calls.

In order to achieve what you want, you have to do this instead:

// common.js
  beforeEach(async () => {
    console.log("Common - Before")
  })

require ('./common'); // requires the above code

describe.only('API', function () {
  it('should do something', async () => {
    console.log("it")
  })
  // many more "it"s
})

otherwise, the beforeEach won't get applied because the hook is not "at the right level of the stack".

[heynemann]

The issue with that is that I have 3 different major "common.js" files for three different modules of my app. I can't have all three execute before each test. That's why I need to include the describe in the common.js.

I have a extensions module for common code, a worker module for the worker of my app and an api module for the rest api. Each has it's common.js for test setup.

I can't have the worker beforeEach happen in each of the tests of the API.

What was happening is that they were accumulating: the API only ran the API common. The extensions ran both the API and extensions. The worker ran all three before each test.

[ORESoftware]

Yep, this is why Mocha has problems IMO, unless you know what you are doing, it's hard to know what to do :) Let me try to solve your issue though. This _will_ work for you.

describe(1, function(){

    require('beforeEach1');   // if you load it here, then the beforeEach will only apply to registered calls inside this describe block

   // do your thing;
    describe(x, function(){

    });

})


describe(2, function(){

    require('beforeEach2');   // ditto above

     // do your thing;
    describe(y, function(){

    });
})


describe(3, function(){

    require('beforeEach3');  // ditto above

  // do your thing;
    describe(z, function(){

    });
})

that should solve your problem. Also considering wrapping your shared code in functions so that you don't accidentally load a file you didn't mean to load. Only if you explicitly call the file.

So maybe do this:

//shared.js / common.js

module.exports = {


   one: function() {

        beforeEach(1, function(){

        })

   },

  two: function() {

        beforeEach(2, function(){

        })

   },

  three: function() {

        beforeEach(3, function(){

        })

   }
};

of course now it's possible to call those functions more than once by accident, whereas if they were just in a module, modules only run/load once and then are cached.

[heynemann]

Thanks! That was very helpful!

[ORESoftware]

no problem amigo

[boneskull]

@ORESoftware Thanks for helping @heynemann.

While this is appreciated, what _isn't_ appreciated is your history of unproductive commentary on Mocha and its authors / maintainers. Constructive criticism is welcome, but your criticism is seldom of this variety.

It's becoming a distraction to not just me, but other maintainers. You will be banned from the mochajs org (and this issue tracker) if we see more of it. Thanks!

[ORESoftware]

@boneskull no comment