Feature: add custom assertions via plugins

[mroderick]

As an author, it is currently rather inconvenient to add custom assertions to referee.

I always end up creating some meta file and importing that

// referee-with-custom-assertions.js
referee.add(/* arguments */);

module.exports = referee;

// some-module.test.js
var referee = require('../test/referee-with-custom-assertions');

This doesn't make it very convenient for me to re-use my domain specific assertions easily across repositories.

It would be really handy, if I could add custom assertions to referee via plugins, in the same fashion as plugins for eslint.

My custom assertions could then be published to an internal registry (or the public registry), and re-used across projects.

// referee.config.js
module.exports = {
    plugins: [
        require('path/to/max/assertions'),
        require('morgan-assertions')
    ]
};

// some-module.test.js
var referee = require('referee');

Thoughts?

[mantoni]

I was wondering the same thing today. While your suggestion is fine for node, how about browser support?

Maybe this can even be achieved without changing anything. E.g. with Mocha your can require additional modules:

mocha -r ./path/to/assertions -r morgan-assertions

When using something browserify based this can also be done the same way.

[mroderick]

How would that work in browsers?

Should the plugins export things into the global scope, that can be detected by referee when it is loaded?

[mantoni]

The plugins can simply require('referee').add(...) as before.

[mroderick]

I am a bit slow today, would that make the config file obsolete?

[mantoni]

Yes. You'd essentially pass the file paths to require to the test runner instead.

[mroderick]

I think we'll need to create a running example of how this would work. Perhaps this can be the foundation of a how-to article about using custom assertions with referee.

[mroderick]

https://github.com/sinonjs/referee-custom-assert-with-mocha

[mgred]

👍 That's awesome, I've stolen your work for the docs 😁