Testing Mongoose Node.JS app

Question

I'm trying to write unit tests for parts of my Node app. I'm using Mongoose for my ORM.

I've searched a bunch for how to do testing with Mongoose and Node but not come with anything. The solutions/frameworks all seem to be full-stack or make no mention of mocking stuff.

Is there a way I can mock my Mongoose DB so I can return static data in my tests? I'd rather not have to set up a test DB and fill it with data for every unit test.

Has anyone else encountered this?

Answer 1

I too went looking for answers, and ended up here. This is what I did:

I started off using mockery to mock out the module that my models were in. An then creating my own mock module with each model hanging off it as a property. These properties wrapped the real models (so that child properties exist for the code under test). And then I override the methods I want to manipulate for the test like save. This had the advantage of mockery being able to undo the mocking.

but...

I don't really care enough about undoing the mocking to write wrapper properties for every model. So now I just require my module and override the functions I want to manipulate. I will probably run tests in separate processes if it becomes an issue.

In the arrange part of my tests:

// mock out database saves
var db = require("../../schema");
db.Model1.prototype.save = function(callback) { 
    console.log("in the mock");
    callback();
};
db.Model2.prototype.save = function(callback) {
    console.log("in the mock");
    callback("mock staged an error for testing purposes");
};