Sinon: Mocks don't work well with onCall

It seems like it doesn't work with .stub either. I get an error saying the method was called with the wrong arguments. Showing the arguments from the first call but the requirements from the second. As if it discards the onCall(0).

var mock = sinon.mock();

mock.exactly(2);
mock.onFirstCall().stub.withExactArgs("bar1", "bar2").returns("bar");
mock.onSecondCall().stub.withExactArgs("foo1", "foo2").returns("foo");

mock("bar1", "bar2");
mock("foo1", "foo2");

mock.verify();

Gives ExpectationError: Anonymous mock received wrong arguments ["bar1", "bar2"], expected ["foo1", "foo2"]

It is neither intended behaviour nor a bug. You're mixing metaphors. onCall and withArgs are both ways of identifying a method invocation.

// So either, 

mock.onCall(0).returns("foo")

// OR

mock.withArgs("arg1", "arg2").returns("foo")

// but not both

Your second example is flawed for the same reason and should probably be re-written using a stub.

    var stub = sinon.stub();

    stub.withArgs("bar1", "bar2").returns("bar");
    stub.withArgs("foo1", "foo2").returns("foo");

    stub("bar1", "bar2");
    stub("foo1", "foo2");

    sinon.assert.calledTwice(stub);

    // verify the 2 calls
    sinon.assert.calledWithExactly(stub, "bar1", "bar2");
    sinon.assert.calledWithExactly(stub, "foo1", "foo2");

    // verify the 2 calls in order
    sinon.assert.callOrder(
        stub.withArgs("bar1", "bar2"),
        stub.withArgs("foo1", "foo2")
    );

Unfortunately, there's no withExactArgs on Stub.

However...

You can identify individual calls to a stub, even when called multiple times with the same arguments. For example

stub.withArgs("foo")
  .onCall(0).returns("a")
  .onCall(1).returns("b");

stub.withArgs("bar")
  .onCall(0).returns("c")
  .onCall(1).returns("d");

If that helps?

@mantoni I think this issue can be closed