Matching an argument with a function in Jasmine

Question

I want to perform a custom assertion about the argument passed to a spied-on function call. Can I supply a callback to be used within the expectation against an argument?

expect(my.method).toHaveBeenCalledWith(jasmine.argumentMatching(myCustomCallback), jasmine.any({}));

... Where jasmine.argumentMatching(myCustomCallback) is pseudo code.

Answer 1

Jasmine spy has a property .calls , which provides information about the number of calls, arguments for particular calls, etc. Take a look at this docs section - Other tracking properties . It depends on your requirements which one would you use, and in documentation it is described very well, but in general:

• .calls.argsFor(n) - returns array of arguments for n-th call

• .calls.allArgs() - returns array of arrays of arguments for all calls

• .calls.mostRecent() , .calls.first() - return an object in form:

   { object: my, args: ['foo', 42], returnValue: undefined }

• .calls.all() - returns array of objects (like one above)

In general it will look like:

spyOn(my, 'method');

my.method('foo', 42);

expect(my.method.calls.argsFor(0)).toEqual(['foo', 42]);