Snare

Snare is a Babel plugin that can help you in monkey patching of functions in your tests.

npm install snarejs

Initalization

.babelrc

{

	"plugins": [
		"snarejs/lib/plugin"
	]
}

API

var snareInstance = snare(fn);

First argument is a function where you want to intercept calls of another functions. When babel plugin finds the initialization it will resolve passed argument and will find a module where function is declared. The function can be received in any way that you prefer: ES6, common.js require.

let fn = require('./module');
let {fn} = require('./module');
let {anotherName: fn} = require('./module');
let fn = require('./module').anotherName;
import fn from './module';
import {fn} from './module';
import {anotherName as fn} from './module'

In any of above cases the plugin searches necessary export in specific module and replaces necessary calls of functions inside. The exports can be common.js or ES6 too.

snareInstance.catchOnce('fnName()', function(fnName, …args){});
snareInstance.catchAll('fnName()', function(fnName, …args){});

The first argument is a string with CallExpression that you want to catch and override. The second argument is the overrider that is called instead of "fnName()".

catchOnce() catches call once. catchAll() catches all calls.

snareInstance.reset('fnName()');

Cancels interceptions of fnName()