Simple module for mocking required dependencies. Works with any testing suite. (https://github.com/mateodelnorte/mockrequire).
Imagine your application uses the following module to onboard a user, in reaction to a recieved event. A service will require the module and call it, passing the event as a parameter. But, in the course of developing your application, you'd like to test the module in isolation from the rest of your code. The module depends on another module, 'my_db_lib'.
How can you test the module in isolation?
var db = require('my_db_lib');
module.exports = function onboardUser (event) {
// we want to test this function's behavior, but need to isolate the behavior of the module apart from the behavior of it's dependency, the db.
db.User.findByEmail(event.email, function (err, user) {
if(err) throw err;
user.onboarding = 'complete';
user.save(function (err) {
if(err) throw err;
});
});
};
MockRequire provides a simple means of allowing you to mock dependencies of any module you require(). Want to unit test your code without ever having to hit a database, even though your code is require-ing your datastore modules directly? MockRequire is exactly what you need.
The following example uses 'mocha' and 'should' to create a unit test for the module above. We also use 'mockrequire' to mock out our dependencies, parts of our module we don't care to isolate in our test.
require('mocha'),
require('should');
var mockrequire = require('mockrequire');
var user = (function() {
return {
save: function (cb) {
cb(null);
this.saved = true;
}
};
})();
// instead of require()ing our handler directly, we can mockrequire() it and supply an object containing any child dependencies we would like to mock as well. Here we're mocking my_db_lib
var onboardUser = mockrequire('./handler', {
'my_db_lib': {
User: {
findByEmail: function (email, cb){
cb(null, user);
}
}
}
});
// we create our unit tests with mocha
describe('userPaymentComplete()', function(){
onboardUser({ email: '[email protected]' });
it('should set onboarding as \'complete\'', function() {
user.should.have.property('onboarding').equal('complete');
});
it('should save user', function() {
user.should.have.property('saved').equal(true);
});
});
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