Sinon error Attempted to wrap function which is already wrapped

Though there is a same question here but I could not find answer to my problem so here goes my question:

I am testing my node js app using mocha and chai. I am using sinion to wrap my function.

describe('App Functions', function(){

  let mockObj = sinon.stub(testApp, 'getObj', (dbUrl) => {
     //some stuff
  });
  it('get results',function(done) {
     testApp.someFun
  });
}

describe('App Errors', function(){

  let mockObj = sinon.stub(testApp, 'getObj', (dbUrl) => {
     //some stuff
  });
  it('throws errors',function(done) {
     testApp.someFun
  });
}

When I try to run this test it gives me error

Attempted to wrap getObj which is already wrapped

I also tried putting

beforeEach(function () {
  sandbox = sinon.sandbox.create();
});

afterEach(function () {
  sandbox.restore();
});

in each describe, but still giving me same error.

Solution 1:

You should restore the getObj in after() function, please try it as below.

describe('App Functions', function(){
    var mockObj;
    before(function () {
            mockObj = sinon.stub(testApp, 'getObj', () => {
                 console.log('this is sinon test 1111');
            });
    });

    after(function () {
        testApp.getObj.restore(); // Unwraps the spy
    });

    it('get results',function(done) {
        testApp.getObj();
    });
});

describe('App Errors', function(){
    var mockObj;
    before(function () {
            mockObj = sinon.stub(testApp, 'getObj', () => {
                 console.log('this is sinon test 1111');
            });
    });

    after( function () {
        testApp.getObj.restore(); // Unwraps the spy
    });

    it('throws errors',function(done) {
         testApp.getObj();
    });
});

Update 2022/01/22

Using sinon's sanbox you could created stub mocks with sandbox.stub() and restores all fakes created through sandbox.restore(), Arjun Malik give an good example

Solution 2:

This error is due to not restoring the stub function properly. Use sandbox and then create the stub using the sandbox. After each test inside the suite, restore the sandbox

  beforeEach(() => {
      sandbox = sinon.createSandbox();
      mockObj = sandbox.stub(testApp, 'getObj', fake_function)
  });

  afterEach(() => {
      sandbox.restore();
  });

Solution 3:

For cases where you need to restore all the methods of one object, you can use the sinon.restore(obj).

Example:

before(() => {
    userRepositoryMock = sinon.stub(userRepository);
});

after(() => {
    sinon.restore(userRepository);
});

Solution 4:

I was also hitting this using the before() and after() hooks of Mocha. I was also using the restore() as mentioned everywhere. Single test file ran fine, multiple did not. Finally found about Mocha root-level-hooks: I did not have my before() and after() inside my own describe(). So it finds all files with before() at the root-level and executes those before starting any tests.

So make sure you have a similar pattern:

describe('my own describe', () => {
  before(() => {
    // setup stub code here
    sinon.stub(myObj, 'myFunc').callsFake(() => {
      return 'bla';
    });
  });
  after(() => {
    myObj.myFunc.restore();
  });
  it('Do some testing now', () => {
    expect(myObj.myFunc()).to.be.equal('bla');
  });
});

Solution 5:

For anyone running into this issue, if you stub or spy on the entire object, and you later do

sandbox.restore()

You'll still get the error. You have to stub/spy the individual methods.

I wasted forever trying to figure out what was wrong.

sinon-7.5.0