Comment tester jQuery avec jasmin pour $ ("# element-id") si utilisé comme $ (ceci)

Question

Je ne sais pas comment gérer ce test de jasmin pour mon JS et sûrement aussi, d'autres personnes ont ce problème.Peut-être que je vais vous tromper ou peut-être que c'est impossible - je n'ai trouvé aucun indice à ce sujet.Le problème a à voir avec le fait que - en jQuery - $ (ceci) n'est pas la même chose que l'élément choisi par ex.$ ("# cet identifiant"):

JavaScript:

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

Test de jasmin (Coffeescript):

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

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

Malheureusement, ce test échoue (avec n'importe quelle variante, comme en train de stocker la référence dans une variable d'abord dans mon test de jasmin), car la fonction n'est pas appelée avec $ ("# bouton-identifiant"), mais est appelée à $ (ceci), et $ (this)!= $ ("# bouton-identifiant").

Quelqu'un peut-il me dire comment accomplir ce test?Je suis assez perdu.Même Great Article de Remy Sharp sur JQuery et $ (this) DIDN 't pouvons-moi davantage.

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.