How to stub nested dependecies with ts-sinon - node.js

Question

I got a simple unit test with the following code:
my-pubsub.spec.ts
import * as tsSinon from 'ts-sinon';
import { myPubSubFunction } from './my-pubsub';
import * as sendEmail from './send-mail';
describe("Notifications PubSub tests", () => {
it("Should trigger audit", (done) => {
const today = new Date()
const data = {
( my data )
}
const spy = tsSinon.default.spy(sendEmail, "sendNotificationMessage")
const dataBuffer = Buffer.from(JSON.stringify(data))
// Call tested function and verify its behavior
myPubSubFunction(dataBuffer)
setTimeout(() => {
// check if spy was called
tsSinon.default.assert.calledOnce(spy)
done()
}, 100)
})
})
And my-pubsub.ts got a call to a function from send-mail with contains a function to set the Api key
import * as sgMail from '#sendgrid/mail';
sgMail.setApiKey(
"MyKey"
) // error in here
export function sendNotificationMessage(mailConfig: any) {
const defaultConfig = {
from: {
email: "noreply#mymail.com",
name: "my name",
},
template_id: "my template",
}
const msg = { ...defaultConfig, ...mailConfig }
return sgMail.send(msg)
}
However when running my tests I got the following error TypeError: sgMail.setApiKey is not a function
Edit: added a bit more code to the send-mail code.
Bellow you can find a bit more code about my-pubsub.ts
my-pubsub.ts
import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';
import moment = require('moment');
import { IModel, ModelType } from '../models/model.model';
import { sendNotificationMessage } from '../shared/send-mail';
const { PubSub } = require("#google-cloud/pubsub")
try {
admin.initializeApp()
} catch (e) {}
const db = admin.firestore()
const pubSubClient = new PubSub()
export const myPubSubTrigger = functions.pubsub
.topic("on-trigger")
.onPublish(async (message) => {
console.log("version 1")
const myMessage = Buffer.from(message.data, "base64").toString("utf-8")
const data: IModel = JSON.parse(myMessage)
( logic to create my object )
/**
* Send email
*/
const result: any = await sendNotificationMessage(myObject)
/**
* Check result
*/
if (result[0].statusCode === 202) {
await docRef.update({ emailSent: true })
}
( another publish to audit the action )
})

Answer 1

The problem is not with tests per se, but incorrect types definition of #sendgrid/mail:
// OK
import sgMail from "#sendgrid/mail";
import { default as sgMail2 } from "#sendgrid/mail";
console.log(sgMail === sgMail2);
sgMail.setApiKey("SG.key");
sgMail2.setApiKey("SG.key2");
// BROKEN
// type definition does not match runtime shape
import * as sgMailIncorrectlyTyped from "#sendgrid/mail";
console.log(sgMailIncorrectlyTyped, sgMailIncorrectlyTyped.setApiKey === undefined);
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