easejs/test/test-class-constructor.js

/**
 * Tests class module constructor creation
 *
 *  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
 */

var common = require( './common' ),
    assert = require( 'assert' ),
    Class  = common.require( 'class' );

// these two variables are declared outside of the class to ensure that they
// will still be set even if the context of the constructor is wrong
var construct_count   = 0,
    construct_context = null;

// create a basic test class
var Foo = Class.extend(
{
    args: null,


    __construct: function()
    {
        construct_count++;
        construct_context = this;

        this.args = arguments;
    },
});

assert.ok(
    ( Foo.prototype.__construct instanceof Function ),
    "Provided properties should be copied to the new class prototype"
);

assert.equal(
    construct_count,
    0,
    "Constructor should not be called before class is instantiated"
);

var args = [ 'foo', 'bar' ],
    obj  = new Foo( args[0], args[1] );

assert.equal(
    construct_count,
    1,
    "Constructor should be invoked once the class is instantiated"
);

assert.equal(
    obj,
    construct_context,
    "Constructor should be invoked within the context of the class instance"
);

assert.notEqual(
    obj.args,
    null,
    "Constructor arguments should be passed to the constructor"
);

assert.equal(
    obj.args.length,
    args.length,
    "All arguments should be passed to the constructor"
);

// check the argument values
for ( var i = 0, len = args.length; i < len; i++ )
{
    assert.equal(
        obj.args[ i ],
        args[ i ],
        "Arguments should be passed to the constructor: " + i
    );
}

var SubFoo = Foo.extend(
{
    args: [ 'should', 'be', 'overwritten' ],
} );

construct_count   = 0;
construct_context = null;

var args2  = [ 'fried', 'pickle' ],
    subobj = new SubFoo( args2[ 0 ], args2[ 1 ] );

assert.equal(
    construct_count,
    1,
    "Parent constructor should be called for subtype if not overridden"
);

assert.equal(
    construct_context,
    subobj,
    "Parent constructor is run in context of the subtype"
);

// this should be implied by the previous test, but let's add it for some peace
// of mind
assert.ok(
    ( ( subobj.args[ 0 ] === args2[ 0 ] )
        && ( subobj.args[ 1 ] == args2[ 1 ] )
    ),
    "Parent constructor sets values on subtype"
);


var subobj2 = SubFoo( args2[ 0 ], args2[ 1 ] );

assert.ok(
    ( subobj2 instanceof SubFoo ),
    "Constructor is self-invoking"
);

assert.equal(
    construct_context,
    subobj2,
    "Self-invoking constructor is run in the context of the new object"
);

assert.ok(
    ( ( subobj2.args[ 0 ] === args2[ 0 ] )
        && ( subobj2.args[ 1 ] == args2[ 1 ] )
    ),
    "Self-invoking constructor receives arguments"
);