refactor busboy constructor - add esm

[Uzlopak]

@kibertoad
I know you assigned esm support, but i took the opportunity to also refactor the whole busboy constructor functionality and write corresponding unit tests.

It makes it also possible to set autoDestroy to true or false, if somebody wants to do that.

test coverage for main.js increases to 100%

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[Uzlopak]

@kibertoad

Maybe if this helps for the approval:
This PR is actually non-backwards-breaking :). You can put the unit tests to master and you will see all the errors thrown are having the same reasons.

123 passing (254ms)
  5 failing

  1) busboy-constructor
       should throw an Error if no options are provided:

      AssertionError: expected [Function] to throw error including 'Busboy expected an options-Object.' but got 'Cannot read property \'highWaterMark\' of undefined'
      + expected - actual

      -Cannot read property 'highWaterMark' of undefined
      +Busboy expected an options-Object.
      
      at Context.<anonymous> (test/main.spec.js:6:40)
      at processImmediate (internal/timers.js:464:21)

  2) busboy-constructor
       should throw an Error if options does not contain headers:

      AssertionError: expected [Function] to throw error including 'Busboy expected an options-Object with headers-attribute.' but got 'Missing Content-Type'
      + expected - actual

      -Missing Content-Type
      +Busboy expected an options-Object with headers-attribute.
      
      at Context.<anonymous> (test/main.spec.js:9:42)
      at processImmediate (internal/timers.js:464:21)

  3) busboy-constructor
       should throw an Error if content-type is not set:

      AssertionError: expected [Function] to throw error including 'Missing Content-Type-header.' but got 'Missing Content-Type'
      + expected - actual

      -Missing Content-Type
      +Missing Content-Type-header.
      
      at Context.<anonymous> (test/main.spec.js:16:55)
      at processImmediate (internal/timers.js:464:21)

  4) busboy-constructor
       should throw an Error if content-type is unsupported:

      AssertionError: expected [Function] to throw error including 'Unsupported Content-Type.' but got 'Unsupported content type: unsupported'
      + expected - actual

      -Unsupported content type: unsupported
      +Unsupported Content-Type.
      
      at Context.<anonymous> (test/main.spec.js:19:86)
      at processImmediate (internal/timers.js:464:21)

  5) busboy-constructor
       if busboy is called with stream options and autoDestroy:true, autoDestroy should be set to true:

      AssertionError: expected false to equal true
      + expected - actual

      -false
      +true
      
      at Context.<anonymous> (test/main.spec.js:36:61)
      at processImmediate (internal/timers.js:464:21)

[kibertoad]

yeah, it looks good, just need a bit of focus to review it throughly. also want to apply the infamous triplet pattern for cross cjs/esm support.

[Uzlopak]

@kibertoad

Do you mean this?

if (typeof define === 'function' && define.amd) {
  define('Busboy', function () {
    return Busboy;
  });
} else if (typeof module !== 'undefined' && module.exports) {
  module.exports = Busboy;
  module.exports.default = Busboy
  module.exports.Busboy = Busboy;
} else {
  global.Busboy = Busboy;
}

[kibertoad]

we've been doing just the second branch without condition in the past. global doesn't seem applicable to node-only lib, do you find first branch useful?

[Uzlopak]

I just copied and modified it from another project. But yes you are right, the last one is for browser compatibility.

[kibertoad]

AMD seems frontend-focused too. So I'd suggest keeping just the second branch without any checks.

[Uzlopak]

@kibertoad

add infamous ejs, cjs triplet :)

[kibertoad]

We also need to update TS types and add import tests.
See https://github.com/pinojs/sonic-boom/blob/master/types/index.d.ts and https://github.com/pinojs/sonic-boom/blob/master/types/index.test-d.ts for how this can be done for the infamous triplet.

[Uzlopak]

@kibertoad
Seems like it was already OK?

[kibertoad]

@Uzlopak I'm not so sure. Busboy in TS exports only a type, not a constructor. BusboyConstructor is exported as a default, but not as Busboy as well, so you can't do named import for a constructor itself (not a type).

[Uzlopak]

@kibertoad
Ok now?