easejs/test/test-class_builder-final.js

/**
 * Tests final members
 *
 *  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' ),
    builder = common.require( 'class_builder' ),

    Class      = common.require( 'class' )
    FinalClass = common.require( 'class_final' )
;


/**
 * Methods declared as final should not be able to be overridden by subtypes.
 * Simple as that.
 */
( function testFinalMethodsCannotBeOverridenBySubtypes()
{
    var Foo = builder.build(
    {
        'final public foo': function() {},
    } );

    try
    {
        // attempt to override (should fail)
        builder.build( Foo,
        {
            'public foo': function() {},
        } );
    }
    catch ( e )
    {
        assert.ok(
            e.message.search( 'foo' ) !== -1,
            "Final error message contains name of method"
        );

        return;
    }

    assert.fail( 'Should not be able to override final methods' );
} )();


/**
 * Due to our static implementation (late static binding), the use of 'final'
 * with properties doesn't make much sense. We have to deal with different
 * problems than languages like Java that truly bind members statically. Consult
 * the documentation for rationale.
 *
 * See also const keyword.
 */
( function testFinalKeywordCannotBeUsedWithProperties()
{
    try
    {
        // attempt to define a 'final' property (should fail)
        builder.build(
        {
            'final public foo': 'bar',
        } );
    }
    catch ( e )
    {
        assert.ok(
            e.message.search( 'foo' ) !== -1,
            "Final property error message contains name of property"
        );

        return;
    }

    assert.fail( "Should not be able to use final keyword with properties" );
} )();


/**
 * The 'abstract' keyword's very point is to state that no definition is
 * provided and that a subtype must provide one. Therefore, declaring something
 * 'abstract final' is rather contradictory and should not be permitted.
 */
( function testFinalyKeywordCannotBeUsedWithAbstract()
{
    try
    {
        // should fail
        builder.build( { 'abstract final foo': [] } );
    }
    catch ( e )
    {
        assert.ok(
            e.message.search( 'foo' ) !== -1,
            "Abstract final error message contains name of method"
        );

        return;
    }

    assert.fail( "Should not be able to use final keyword with abstract" );
} )();


/**
 * Ensure that FinalClass properly forwards data to create a new Class.
 */
( function testFinalClassesAreValidClasses()
{
    assert.ok( Class.isClass( FinalClass( {} ) ),
        "Final classes should generate valid classes"
    );
} )();


/**
 * When a class is declared as final, it should prevent it from ever being
 * extended. Ever.
 */
( function testFinalClassesCannotBeExtended()
{
    try
    {
        // this should fail
        FinalClass( 'Foo', {} ).extend( {} );
    }
    catch ( e )
    {
        assert.ok(
            e.message.search( 'Foo' ) !== -1,
            "Final class error message should contain name of class"
        );

        return;
    }

    assert.fail( "Should not be able to extend final classes" );
} )();


/**
 * Ensure we're able to create final classes by extending existing classes.
 */
( function testCanCreateFinalSubtypes()
{
    var Foo        = builder.build( {} ),
        FinalNamed = FinalClass( 'FinalNamed' ).extend( Foo, {} ),
        FinalAnon  = FinalClass.extend( Foo, {} )
    ;

    // named
    assert.throws( function()
    {
        FinalNamed.extend( {} );
    }, Error, "Cannot extend final named subtype" );

    // anonymous
    assert.throws( function()
    {
        FinalAnon.extend( {} );
    }, Error, "Cannot extend final anonymous subtype" );
} )();