Calling different callbacks for stub on firstcall and second call

Question

I'm looking for a way in sinon to call different functions in first and second call to the stub method.

Here is an example:

var func1 = function(connectionPolicy, requestOptions, callback) {
  callback({code: 403});
}

var func2 = function(connectionPolicy, requestOptions, callback) {
  callback(undefined);
}

var stub = sinon.stub();

// Something of this form
stub.onCall(0) = func1;
stub.onCall(1) = func2;

request.createRequestObjectStub = stub;

So that when request.createrequestObjectStub gets called internally(when calling a public API), I see this behavior.

• Sinon version: 1.17.4
• Environment: Node JS

Answer 1

The only way I found to do what you want (with onCall(index) and an anonymous stub) is with bind JS Function.

This would be:

stub.onCall(0).returns(func1.bind()());
stub.onCall(1).returns(func2.bind()());

If you use stub.onCall(0).returns(func1()); the function func1 is executed when defining that onCall, that is why you need the .bind.

Anyway, you have other options, like returning a value directly with .onCall(index).returns(anObject); or defining a counter that is incremented each time your stubbed method is called (this way you know in which n-call you are and you can return different values).

For these three approaches, you can see the following fiddle with examples: https://jsfiddle.net/elbecita/jhvvv1h1/

Answer 2

onCall worked for me. my code looks like:

const stubFnc = sinon.stub(myObject, "myFunction");
stubFnc.onCall(0).returns(mockObject1);
stubFnc.onCall(1).returns(mockObject2);

Answer 3

This is an old thread, but atleast as of Sinon 1.8, a more efficient way to solve this would be chaining sinon.onCall(arg) with callsFake().

So, in your use-case, you could do the following:

var func1 = function(connectionPolicy, requestOptions, callback) {
    callback({code: 403});
}
var func2 = function(connectionPolicy, requestOptions, callback) {
    callback(undefined);
}

var stub = sinon.stub();

// Solution

stub.onCall(0).callsFake(func1);
stub.onCall(1).callsFake(func2);

request.createRequestObjectStub = stub;

Answer 4

You can use callsArg and callsArgWith from sinon.stub() to make sinon call the callbacks

Causes the stub to call the argument at the provided index as a callback function. stub.callsArg(0); causes the stub to call the first argument as a callback. source

Then you can do something like:

  myStub.onCall(0).callsArgWith(0, first);
  myStub.onCall(1).callsArgWith(0, second);