devmcc-require-hook v1.1.4

require-hook

Allows you to change the result of require, by using hooks. This package supports two types of hooks; scoped hook and a global hook.

Scoped hook

A hook that is registered during the runtime of a scope.

tester.js

const requireHook = require('devmcc-require-hook')

requireHook(
    // The hook function.
    (path, resolve) => {
        // Will resolve with the first argument.
        if (path == './test-module-function') {
            const mock = {
                get(arg) {
                    return 'mocked: ' + arg
                }
            }
            resolve(mock, true)
            return
        }

        // Will resolve with the original module.
        resolve()
    },
    // The scope function.
    () => require('./test-module')
)

test-module.js

const mod = require('./test-module-function')

console.log(mod.get('abc'))

test-module-function.js

module.exports = {
    get(arg) {
        return 'original: ' + arg
    }
}

Running test-module.js directly will output original: abc.
Running tester.js will output mocked: abc.

Global hook

A hook that is permantently registered until removed.

hook.js

const requireHook = require('devmcc-require-hook')

// Calling requireHook without arguments will return the HookObject.
// The method "addHook" returns a HookKey.
const hookKey = requireHook().addHook((path, resolve) => {
    if (path == './test') {
        resolve('./fake')
    }
})

console.log(require('./test'))

// This will remove the hook.
requireHook().removeHook(hookKey)

test.js

module.exports = 'test'

fake.js

module.exports = 'fake'

Running hook.js will output fake.

HookObject

The HookObject contains three methods:

• addHook - adds a global hook, returns a HookKey.
• removeHook - Removes a global hook based on the HookKey.
• getHooks - Returns a mapping of all the current hooks.

Multiple hooks

It is possible to have multiple hooks, they will be invoked in chronological order.
If one hook resolves, then all the other hooks will receive undefined, rather than a resolve function.

Resolving modules

Calling resolve without arguments will resolve with the original module.
Calling resolve with only a string will replace the import path, please keep in mind that the path is relative.
Calling resolve with a second argument as true will resolve with the first argument.