easejs/test/test-class-extend.js

/**
 * Tests class module extend() method
 *
 *  Copyright (C) 2010 Mike Gerwitz
 *
 *  This file is part of ease.js.
 *
 *  ease.js is free software: you can redistribute it and/or modify it under the
 *  terms of the GNU Lesser 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 Lesser General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author  Mike Gerwitz
 * @package test
 */

require( './common' );

var assert = require( 'assert' ),
    Class  = require( 'class' );

var foo_props = {
        one: 1,
        two: 2,
    },
    Foo = Class.extend( foo_props );

assert.ok(
    ( Foo.extend instanceof Function ),
    "Created class contains extend method"
);

var sub_props = {
        three: 3,
        four:  4,
    },
    SubFoo = Foo.extend( sub_props );

assert.ok(
    ( SubFoo instanceof Object ),
    "Subtype is returned as an object"
);

// ensure properties were inherited from supertype
for ( var prop in foo_props )
{
    assert.equal(
        foo_props[ prop ],
        SubFoo.prototype[ prop ],
        "Subtype inherits parent properties: " + prop
    );
}

// and ensure that the subtype's properties were included
for ( var prop in sub_props )
{
    assert.equal(
        sub_props[ prop ],
        SubFoo.prototype[ prop ],
        "Subtype contains its own properties: " + prop
    );
}

assert.ok(
    ( new SubFoo() instanceof Foo ),
    "Subtypes must be considered to be instances of their supertypes"
);


//         Foo
//          |
//        SubFoo
//        /   \
// SubSubFoo  SubSubFoo2
//
var SubSubFoo  = SubFoo.extend(),
    SubSubFoo2 = SubFoo.extend();

assert.ok(
    ( new SubSubFoo() instanceof Foo ),
    "Sub-subtypes should be instances of their super-supertype"
);

assert.ok(
    !( new SubFoo() instanceof SubSubFoo ),
    "Supertypes should not be considered instances of their subtypes"
);

assert.ok(
    !( new SubSubFoo2() instanceof SubSubFoo ),
    "Subtypes should not be considered instances of their siblings"
);


// to test inheritance of classes that were not previously created via the
// Class.extend() method
var OtherClass = function() {};
OtherClass.prototype =
{
    foo: 'bla',
};

var SubOther = Class.extend( OtherClass,
{
    newFoo: 2,
});


assert.equal(
    SubOther.prototype.foo,
    OtherClass.prototype.foo,
    "Prototype of existing class should be copied to subclass"
);

assert.notEqual(
    SubOther.prototype.newFoo,
    undefined,
    "Subtype should contain extended members"
);


assert.throws( function()
{
    Class.extend( OtherClass,
    {
        foo: function() {},
    });
}, TypeError, "Cannot override property with a method" );


var AnotherFoo = Class.extend(
{
    arr: [],
    obj: {},
});

var Obj1 = new AnotherFoo(),
    Obj2 = new AnotherFoo();

Obj1.arr.push( 'one' );
Obj2.arr.push( 'two' );

Obj1.obj.a = true;
Obj2.obj.b = true;

// to ensure we're not getting/setting values of the prototype (=== can also be
// used to test for references, but this test demonstrates the functionality
// that we're looking to ensure)
assert.ok(
    ( ( Obj1.arr[ 0 ] === 'one' ) && ( Obj2.arr[ 0 ] === 'two' ) ),
    "Multiple instances of the same class do not share array references"
);

assert.ok(
    ( ( ( Obj1.obj.a === true ) && ( Obj1.obj.b === undefined ) )
        && ( ( Obj2.obj.a === undefined ) && ( Obj2.obj.b === true ) )
    ),
    "Multiple instances of the same class do not share object references"
);

var arr_val = 1;
var SubAnotherFoo = AnotherFoo.extend(
{
    arr: [ arr_val ],
});

var SubObj1 = new SubAnotherFoo(),
    SubObj2 = new SubAnotherFoo();

assert.ok(
    ( ( SubObj1.arr !== SubObj2.arr ) && ( SubObj1.obj !== SubObj2.obj ) ),
    "Instances of subtypes do not share property references"
);

assert.ok(
    ( ( SubObj1.arr[ 0 ] === arr_val ) && ( SubObj2.arr[ 0 ] === arr_val ) ),
    "Subtypes can override parent property values"
);

assert.throws( function()
{
    Class.extend(
    {
        __initProps: function() {},
    });
}, Error, "__initProps() cannot be declared (internal method)" );


var SubSubAnotherFoo = AnotherFoo.extend(),
    SubSubObj1       = new SubSubAnotherFoo(),
    SubSubObj2       = new SubSubAnotherFoo();

// to ensure the effect is recursive
assert.ok(
    ( ( SubSubObj1.arr !== SubSubObj2.arr )
        && ( SubSubObj1.obj !== SubSubObj2.obj )
    ),
    "Instances of subtypes do not share property references"
);