Cómo probar jquery con jazmín por $ ("# elemento-id") si se usa como $ (esto)

Question

No sé cómo ejecutar esta prueba de jazmín para mi JS y seguramente también otras PPL tienen este problema.Tal vez estoy haciendo mal o tal vez es imposible, no encontré ninguna pista sobre esto.El problema tiene que ver con el hecho de que, en jQuery, $ (esto) no es lo mismo que el elemento elegido por E.G.$ ("# esta identificación"):

javascript:

[..]
$("#button-id").on("click", function(e) { callSomeFunctionWith( $(this) ); } );

Prueba de jazmín (Coffeescript):

[..]
spyOn some.object, "callSomeFunctionWith"
spyOnEvent( $("#button-id"), 'click' )

$("#button-id").trigger( "click" )
expect( some.object.callSomeFunctionWith ).toHaveBeenCalledWith( $("#button-id") )

Desafortunadamente, esta prueba falla (con cualquier variación, como almacenar la referencia a la variable primero en mi prueba de jazmín), porque la función no se llama con $ ("# botón-ID"), pero en su lugar se llama con $ (esto), y $ (esto)!= $ ("# botón-ID").

¿Alguien puede decirme cómo lograr esta prueba?Estoy bastante perdido.Incluso Remy Sharp's Gran Artículo sobre jQuery y $ (esto) Didn 'T Dame más lejos.

Answer 1

Ok, now I've got the solution to my problem. The solution is easy, the explanation not. I'll explain the solution from scratch.

This is my Javascript code with jQuery that I want to test using jasmine-jquery:

$( "input.toggler" ).on( "click", function( e ) {
  [...]
  doSomethingWith( $(this) );
} );

And now using Jasmine-jQuery I want to ensure that the JS function "doSomethingWith" gets called with the correct "$(this)".

First one might think that $(this) === $( "input.toggler" ), but that is not true. Inside the callback function of the click handler, the $(this) jQuery uses is neither the jQuery object $( "input.toggler" ) nor the DOM element referenced by that object. As Remy Sharp explains in his really nice article "jQuery's this: demystified", the "this" inside the callback function is the DOM element, but $(this) creates a jQuery object from that DOM element. And that is not identical to the jQuery object $( "input.toggler" ).

So if you want to test this with Jasmine using the function "toHaveBeenCalledWith", you have to first extract the DOM element using either document.getElementById(...) or else document.getElementsByTagName(...)[INDEX] (where INDEX is the index of the element you want, since the latter function gives you an array of DOM elements), which is plain old Javascript. Then, when you have extracted the DOM element wanted, you have to create a jQuery-object from it by enclosing it in $( and ).

My passing Jasmine-jQuery-test finally looks something like this (using Coffeescript):

it "does something with my input element", ->
  DOM_input_element = document.getElementsByTagName( "input" )[0] # Choose the correct DOM element here

  spyOn myobject.functions, "doSomethingWith"
  spyOnEvent( $( 'input.toggler' ), 'click' )

  [...]

  $( 'input.toggler' ).trigger( 'click' )

  # Check for changes after click:
  expect( myobject.functions.doSomethingWith ).toHaveBeenCalledWith( $( DOM_input_element ) )

So the "$(this)" from my Javascript code translates to "$(DOM_input_element)" in my Jasmine-jQuery test.

Hopefully this helps you with your projects! It took me quite a while to figure this out.