Testing serverless with Mocha plugin - testing

Question

I have been using serverless for a while now, however this is the first time I'm trying to use mocha for writing tests. When I'm trying to run the following sls create test --function insiders/create.create I get the following error Cannot read property 'handler' of undefined. This is how my serverless.yml looks like for the handler I have created
createInsider:
handler: insiders/create.create
events:
- http:
path: insiders
method: post
cors: true
This is how the plugin Mocha is defined
plugins:
- serverless-mocha-plugin
The code is deployed and it works fine. The namespacing is as insiders/create.js is where I have defined my function.
module.exports.create = () => {}
I have also tried the following ways
sls create test --function insiders/create
sls create test --function create

Answer 1

Not sure if it answers your question, but since majority of the business logic for serverless code is just regular javascript, you can use mocha directly for unit testing.
npm install --save-dev mocha
In package.json
"test": "mocha test/**/*test.js",
Create a test folder and corresponding test files under it
Ex: for src/insiders/create.js create test/insiders/create.test.js
For every handler test the outputs for different inputs
For callback style
describe('create', () => {
it('should execute', (done) => {
const event = {};
const context = {};
const callback = (_, response) => {
//assert required things
done();
};
const handler = require('../../src/insiders/create.js');
handler(event, context, callback)
});
});
For async await style
describe('create', () => {
it('should execute', async () => {
const event = {};
const handler = require('../../src/insiders/create.js');
const result = await handler(event);
//assert the result
});
});
We use this style and it works very well for us.
Edit: Fix the mocha glob pattern to search recursively for all test files.