sinon.js : stub call does not increment callCount

Question

sinon.js 9.0.2

In test I create a stub:

test.js

const myHandler = {
  handle: (some_var_to_pass) => sinon.stub()["resolves"]([{ whatever: "whatever" }]),
};

Then hit the actual code from the test as some endpoint request (with async / await) which executs the code below:

code.js

module.exports = (myHandler) => ({
  getStuff: async (req, res, next) => {
  const var1 = "something1";
  const var2 = "something2";
  const my_response = await myHandler.handle()(var1, var2);

  console.log("my response", JSON.stringify(my_response)); //correct, returns { whatever: "whatever"}
  console.log("Executed stub: ", myHandler.handle(some_var_to_pass).callCount); //always returns zero

I control that myHandler.handle correctly goes through the stub creation and the my_response is

{ whatever: "whatever"}

However, myHandler.handle().callCount remains zero (not undefined). What am I missing to make it increment correctly? Or I need to actually set .callCount return to 1 when I create the stub (would be weird)?

Answer 1

You didn't stub myHandler.handle method. You only stub the function which myHandler.handle method returned. Unit test solution:

code.js:

module.exports = (myHandler) => ({
  getStuff: async (req, res, next) => {
    const var1 = 'something1';
    const var2 = 'something2';
    const my_response = await myHandler.handle()(var1, var2);
    return my_response;
  },
});

code.test.js:

const code = require('./code');
const sinon = require('sinon');

describe('64468517', () => {
  it('should pass', async () => {
    const returnedFn = sinon.stub().resolves([{ whatever: 'whatever' }]);
    const myHandler = {
      handle: sinon.stub().returns(returnedFn),
    };
    await code(myHandler).getStuff();
    expect(myHandler.handle.callCount).to.be.eq(1);
    sinon.assert.calledOnce(myHandler.handle);
    sinon.assert.calledWithExactly(returnedFn, 'something1', 'something2');
  });
});

unit test result:

  64468517
    ✓ should pass


  1 passing (13ms)

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