toHaveBeenCalledWith: equal vs. identical arguments

[tbus...@eclipsesource.com]

Hi there.

The following code would pass in jasmine:
      var spy = jasmine.createSpy();
      spy( {} );
      expect( spy ).toHaveBeenCalledWith( {} );

Which I find somewhat dangerous, since the two objects not the same instance.
The follwing fails:

      expect( spy.mostRecentCall.args[ 0 ] ).toBe( {} );

Is there a way to use toHaveBeenCalledWith to check for identity? I know I can use the above, but then I might get into trouble if there are multiple calls.

Greetings,
Tim

[Ben Loveridge]

Tim,

You can write a custom matcher that does this.

Below is some sample code that demonstrates how this might can be done. This example would need to be improved upon to be a good general purpose tool -- if you decide to go this route I suggest taking a look at the source for the toHaveBeenCalledWith matcher and adapt it as necessary because it will capture a lot more of the edge cases than the sample below, which only works when testing for the first argument and continues to process all calls even if it's already found a match; I meant this to be clean and short, not a full robust solution.

  beforeEach(function() {

    jasmine.getEnv().currentSpec.addMatchers({

      toHaveBeenCalledWithExactly: function(expected) {

        var self = this, matched = false;

        this.actual.calls.forEach(function(call, i) {

          if(self.actual.argsForCall[i][0] === expected) {

            matched = true;

          }

        });

        return matched;

      }

    });

  });

  it('should be able to use object identity when comparing function arguments', function() {

    var a = {}, b = {};

    var spy = jasmine.createSpy();

    spy(a);

    expect(spy).toHaveBeenCalledWith(b); // true

    expect(spy).toHaveBeenCalledWithExactly(a); // true

    expect(spy).toHaveBeenCalledWithExactly(b); // false

  });

Cheers,

- Ben

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