Jest - How to mock a function inside available function - node.js

Question

I have functions in a file as below:
import logger from 'logger-module';
import spir from '../spir';
const spirA = new spir(
process.env.USERNAME,
process.env.PASSWORD,
process.env.API_KEY,
process.env.SMS_WORKSPACE_ID,
process.env.SMS_TEMPLATE_ID
);
const spirSMS = params => {
return new Promise((resolve, reject) => {
spirA.sms(params).then(resolve, reject);
});
};
export const send = params => {
logger.info('Sending new sms...');
const { to: recipients, invalidNumber } = params;
const promises = recipients.map(number =>
spirSMS({ to: number, subject: params.subject, body: params.body })
);
return Promise.all(promises).then(() => {
logger.info(`SMS has been sent to ${recipients.toString()}!`);
return {
message: `SMS has been sent to ${recipients.toString()}`,
data: {
recipients,
invalid_recipients: invalidNumber
}
};
});
};
How to I can mock spirSMS inside recipients.map
I found it to be a loop function so I'm not sure how to mock it.
Many thanks!

Answer 1

I would probably use Classes here for better testability of your code. somethink like this
class SomeClass {
constructor(spirSms) {
this.spirSms_ = spirSms;
}
send(params) {
logger.info('Sending new sms...');
const { to: recipients, invalidNumber } = params;
const promises = recipients.map(number =>
this.spirSms_({ to: number, subject: params.subject, body: params.body })
);
return Promise.all(promises).then(() => {
logger.info(`SMS has been sent to ${recipients.toString()}!`);
return {
message: `SMS has been sent to ${recipients.toString()}`,
data: {
recipients,
invalid_recipients: invalidNumber
}
};
});
}
}
module.exports = SomeClass;
and then you will have some main.js which will instantiate your class and inject spirSms
const spirA = new spir(
process.env.USERNAME,
process.env.PASSWORD,
process.env.API_KEY,
process.env.SMS_WORKSPACE_ID,
process.env.SMS_TEMPLATE_ID
);
const spirSMS = params => {
return new Promise((resolve, reject) => {
spirA.sms(params).then(resolve, reject);
});
};
const someClass = new SomeClass(spirSMS);
someClass.send(params);
Now in your test when you will test SomeClass, you can inject any mock spirSms which will basically do what you are looking for.
Hope this helps.