Possible to stub constructors?

For example-

In my ‘email.js’ I have:

var mandrill = require('mandrill-api/mandrill');
var mandrill_client = new mandrill.Mandrill('API_KEY_HERE');

exports.sendTemplate = function(templateName, to, variables, callback) {

    console.log('mandrill_client === ', mandrill_client)

    var message = {
        //omitted for brevity
    };

    mandrill_client.messages.sendTemplate({
        template_name: templateName,
        template_content: [],
        message: message,
    }, function(result) {
        //... do something
        return callback();
    }, function(err) {
        //...
    });
}

Then, in my test, I want to stub out mandrill, so that when a new mandrill_client is created, it gets my stubbed version, ultimately with a sinon.spy on mandrill_client.messages.sendTemplate

//not sure what mandrillStub should be??

email = proxyquire('../../../app/helpers/email', {
    'mandrill-api/mandrill': mandrillStub
});

Is this possible?

[bendrucker]

Sure – there’s nothing special here. Proxyquire is changing what require itself returns. You’re not mutating shared values and so you specifically can stub constructors and other primitives that you cannot mutate through a shared reference between your source and test code.

Here’s a rough start to get you going:

function MockMandrill (key) {
  this.messages = {
    sendTemplate: sinon.stub()
  }
}

var mandrillStub = {Mandrill: MockMandrill}

[phrozen]

I’m having the same problem as @neilghosh How do I stub a class constructor and methods?