CODEWITHSUNDEEP
javascriptsinon
srgbnd
srgbnd

Reputation: 5644

Stub an object which is inside another object constructor

How to stub this.desires.eat?

const sinon = require('sinon');
const expect = require('expect.js');

class Cat {
  constructor() {
    this.desires = {
      eat: () => 'for a mouse'
    }
  }

  breakfast() {
    return 'go ' + this.desires.eat();
  }
}

const twinky = new Cat();

sinon.stub(twinky, 'desires.eat', () => {
  return 'fishing';
});

describe('test cat', () => {
  it('cat is going to have breakfast', (done) => {
    const solution = twinky.breakfast();
    expect(solution.includes('fishing')).to.be(true);
    done();
  });
});

Now I have the following error:

/media/trex/safe1/Development/app/node_modules/sinon/lib/sinon/util/core.js:115
                    throw error;
                    ^

TypeError: Attempted to wrap undefined property desires.eat as function
    at Object.wrapMethod (/media/trex/safe1/Development/app/node_modules/sinon/lib/sinon/util/core.js:106:29)
    at Object.stub (/media/trex/safe1/Development/app/node_modules/sinon/lib/sinon/stub.js:67:26)
    at Object.<anonymous> (/media/trex/safe1/Development/app/server/lib/test.js:19:7)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)

Upvotes: 1

Views: 108

Answers (1)

T.J. Crowder
T.J. Crowder

Reputation: 1075209

From the docs it looks like:

sinon.stub(twinky.desires, 'eat', () => {
    return 'fishing';
});

E.g., since the method is on twinky.desires, pass that in rather than twinky and then just pass eat as the method name. Apparently sinon doesn't parse dotted notation strings and dive down into the object (which is perfectly reasonable for it not to do).

Upvotes: 1

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