CODEWITHSUNDEEP
javascriptnode.jstypescriptmocha.js
ENV
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Reputation: 1282

How to increase code coverage for Mocha testing on basic Typescript example?

I want to get a better understanding of how to test these kinds of functions in Typescript using mocha. Namely, I have the following small file:

import { Request, Response } from 'express';

export const ping = (req: Request, res: Response) => {
    res.send('pong');
};

export const health = (req: Request, res: Response) => {
    res.send('OK');
};

This exercise may be trivial since there's not much to test here but below I have some basic mocha tests:

 describe('Health Tests', () => {
    it('Check ping', () => {
        expect(ping).to.not.be.null;
    })
    it('Check health', () => {
        expect(health).to.not.be.null;
    })
})

When I run code coverage on this test I get: 50% Stmts | 100% Branch | 0% Funcs | 50% Lines. Especially because this is such a small bit of code, I want to get 100% coverage on all of the categories if possible. Would anyone have any advice on how to accomplish this? Also, could someone please explain why I have 0% coverage for functions? By checking ping or health, am I not also then calling a function and hence, testing that as well.

Any advice would be much appreciated!

Upvotes: 1

Views: 1613

Answers (1)

Lin Du
Lin Du

Reputation: 102337

You need to use some mock/stub library like sinonjs. Here is unit test solution with 100% coverage:

index.ts:

import { Request, Response } from 'express';

export const ping = (req: Request, res: Response) => {
  res.send('pong');
};

export const health = (req: Request, res: Response) => {
  res.send('OK');
};

index.test.ts:

import { ping, health } from './';
import sinon from 'sinon';

describe('63065938', () => {
  describe('#ping', () => {
    it('should pass', () => {
      const mReq = {};
      const mRes = { send: sinon.stub() };
      ping(mReq, mRes as any);
      sinon.assert.calledWith(mRes.send, 'pong');
    });
  });

  describe('#health', () => {
    it('should pass', () => {
      const mReq = {};
      const mRes = { send: sinon.stub() };
      health(mReq, mRes as any);
      sinon.assert.calledWith(mRes.send, 'OK');
    });
  });
});

unit test result with 100% coverage:

  63065938
    #ping
      ✓ should pass
    #health
      ✓ should pass


  2 passing (12ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |     100 |      100 |     100 |     100 |                   
 index.ts |     100 |      100 |     100 |     100 |                   
----------|---------|----------|---------|---------|-------------------

Upvotes: 2

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