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easejs/test/Class/InteropTest.js

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JavaScript

/**
* Tests class interoperability with vanilla ECMAScript
*
* Copyright (C) 2014 Mike Gerwitz
*
* This file is part of GNU ease.js.
*
* ease.js is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Note that these tests all use the `new' keyword for instantiating
* classes, even though it is not required with ease.js; this is both for
* historical reasons (when `new' was required during early development) and
* because we are not testing (and do want to depend upon) that feature.
*/
require( 'common' ).testCase(
{
caseSetUp: function()
{
this.Class = this.require( 'class' );
},
/**
* While this may seem at odds with ease.js' philosophy (because ease.js
* methods are *not* virtual by default), we do not have much choice in
* the matter: JavaScript is very lax and does not offer a way to
* declare something as virtual or otherwise. Given that, we have to
* choose between implicit virtual methods, or never allowing the user
* to override methods inherited from a prototype. The latter is not a
* wise choice, since there would be no way to change that behavior.
*
* Of course, if such a distinction were important, a wrapper class
* could be created that simply extends the prototype, marks methods
* virtual as appropriate, and retain only that reference for use from
* that point forward.
*/
'Methods inherited from a prototype are implicitly virtual': function()
{
var expected = {};
var P = function()
{
this.foo = function()
{
return null;
};
}
var Class = this.Class,
inst;
// if an error is thrown here, then we're probably not virtual
this.assertDoesNotThrow( function()
{
inst = Class.extend( P,
{
'override foo': function()
{
return expected;
}
} )();
} );
// the sky is falling if the above worked but this didn't
this.assertStrictEqual( inst.foo(), expected );
},
/**
* Complement to the above test.
*/
'Prototype method overrides must provide override keyword': function()
{
var P = function()
{
this.foo = function() {};
};
var Class = this.Class;
this.assertThrows( function()
{
Class.extend( P,
{
// missing override keyword
foo: function() {},
} );
} );
},
} );