CODEWITHSUNDEEP
javascriptunit-testing
Gareth Bowen
Gareth Bowen

Reputation: 949

How can I unit test anonymous callbacks passed to JavaScript functions?

I'm creating a jQuery UI autocomplete widget passing in a callback function, like this:

input.autocomplete( {
    ...,
    select: function ( event, ui ) {
        valueField.val( ui.item.id );
    },
    ...
} );

How can I unit test the select function to assert that when it's called the valueField is updated with the correct value?

Upvotes: 1

Views: 453

Answers (2)

Bryan Oakley
Bryan Oakley

Reputation: 386305

If you're wanting to unit test your javascript, the best plan is to create first class functions for your callbacks.

Upvotes: 1

Gareth Bowen
Gareth Bowen

Reputation: 949

Using JsMockito you can capture the parameter passed in to the autocomplete function, eg: 

var params;
when( input ).autocomplete().then( function ( p ) {
    params = p;
} );

By doing this you're saving the reference to the anonymous function, so you can call it later.

params.select( null, { item: { id: someId } } );
verify( valueField ).val( someId );

This technique can also be used for functions that are private, for example, when using the module pattern.

Upvotes: 0

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