prunk

prunk

prunk is a mocking utility for node.js require(). It allows you to mock or suppress imports based on their name, regular expressions or custom test functions.

Example

Given you have a React component you want to test. However, since this component imports a SCSS file you cannot the import component directly. At this point, you either can introduce a pre-compiler, loader or whatever your test framework supports or you can simply mock the import.

// MyComp.js
import { Component } from 'react';
import 'style.scss';

export default class Mycomp extends Component {
    // ...
}

// MyComp.spec.js
const prunk = require('prunk');

prunk.mock('style.scss', 'no scss, dude.');
// or
prunk.mock( function(req) { return 'style.scss' === req; }, 'no scss, dude');
// or better
prunk.mock( /\.(css|scss|sass)$/, 'no styles, dude');

const MyComp = require('./MyComp');

In the test require() is used instead of import because some pre-compilers move all imports to the top of the file and that would make the mocking impossible. If you use mocha you can use compiler for that.

If you just and to make sure some things don't get imported you can suppress them. Then, they will always return undefined;

// MyComp.spec.js
const prunk = require('prunk');

prunk.suppress('style.scss');
// or
prunk.suppress( function(req) { return 'style.scss' === req; } );
// or better
prunk.suppress( /\.(css|scss|sass)$/ );

const MyComp = require('./MyComp');

API

prunk.mock(test, value)

Mocks the given import with the given value. test can be a function that is used to compare whatever is required and returns true or false. If the return value is truthy the import will be mocked with the given value.

The function's arguments are the same as with Module._load. Most of the time you will look at the first argument, a string.

var mockStyles = (req) => 'style.css' === req;
prunk.mock( mockStyles, 'no css, dude.');

test can also be a RegExp that is matched agains the name of the import or a string. It can be anything else, too, if your imports are gone totally crazy.

prunk.mock( 'style.css', 'no css, dude.' );
prunk.mock( /\.(css|scss|sass|less)/, 'no styles, dude.');

This function returns the prunk object so that you can chain calls.

prunk.mock( ... )
     .mock( ... )
     .mock( ... );

prunk.unmock(test)

Removes the mock registered for the given test. unmock() uses strict equal to compare the registered mocks.

This function returns the prunk object so that you can chain calls.

prunk.unmockAll()

Removes all mocks. This function returns the prunk object so that you can chain calls.

prunk.suppress(test)

Suppresses all imports that matches the given test. test can be a function that is used to compare whatever is required and returns true or false. If the return value is truthy the import will be suppressed and thus returns undefined.

The function's arguments are the same as with Module._load. Most of the time you will look at the first argument, a string.

var mockStyles = (req) => 'style.css' === req;
prunk.mock( mockStyles, 'no css, dude.');

test can also be a RegExp that is matched agains the name of the import or a string or something else.

prunk.mock( 'style.css', 'no css, dude.' );
prunk.mock( /\.(css|scss|sass|less)/, 'no styles, dude.');

This function returns the prunk object so that you can chain calls.

prunk.unsuppress(test)

Removes the mock registered for the given test. unsuppress() uses strict equal to compare the suppressed imports. This function returns the prunk object so that you can chain calls.

prunk.unsuppressAll()

Removes all suppressed imports. This function returns the prunk object so that you can chain calls.

Documentation

Documented source.