774 lines
23 KiB
JavaScript
774 lines
23 KiB
JavaScript
/**
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* Tests class member visibility (public, private, protected)
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*
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* Copyright (C) 2010 Mike Gerwitz
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*
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* This file is part of ease.js.
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*
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* ease.js is free software: you can redistribute it and/or modify it under the
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* terms of the GNU Lesser General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
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* for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @author Mike Gerwitz
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*/
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var common = require( './common' ),
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Class = common.require( 'class' ),
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Interface = common.require( 'interface' ),
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util = common.require( 'util' ),
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pub = 'foo',
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prot = 'bar',
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priv = 'baz',
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pubf = function() { return pub; },
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protf = function() { return prot; },
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privf = function() { return priv; },
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// new anonymous class instance
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Foo = Class.extend( {
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'public pub': pub,
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'protected peeps': prot,
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'private parts': priv,
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'public pubf': pubf,
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'protected protf': protf,
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'private privf': privf,
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'virtual public getProp': function( name )
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{
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// return property, allowing us to break encapsulation for
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// protected/private properties (for testing purposes)
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return this[ name ];
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},
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/**
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* Does the same as the above, but we won't override this one
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*/
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'public nonOverrideGetProp': function( name )
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{
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return this[ name ];
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},
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/**
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* Allows us to set a value from within the class
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*/
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'public setValue': function( name, value )
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{
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this[ name ] = value;
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},
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'public getSelf': function()
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{
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return this;
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},
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'virtual public getSelfOverride': function()
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{
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// override me
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},
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'public getPrivProp': function()
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{
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return this.parts;
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},
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'public invokePriv': function()
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{
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return this._priv();
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},
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'private _priv': function()
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{
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return priv;
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},
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}),
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// instance of Foo
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foo = Foo(),
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// subtype
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SubFoo = Foo.extend({
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'private _pfoo': 'baz',
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'override public getSelfOverride': function()
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{
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// return this from overridden method
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return this;
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},
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/**
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* We have to override this so that 'this' is not bound to the supertype
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*/
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'override public getProp': function( name )
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{
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// return property, allowing us to break encapsulation for
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// protected/private properties (for testing purposes)
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return this[ name ];
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},
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'private myOwnPrivateFoo': function() {},
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}),
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sub_foo = SubFoo(),
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sub_sub_foo = SubFoo.extend( {} )()
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;
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require( 'common' ).testCase(
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{
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/**
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* Public members are the only members added to the instance's prototype to
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* be accessible externally
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*/
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'Public members are accessible externally': function()
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{
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this.assertEqual(
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foo.pub,
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pub,
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"Public properties are accessible via public interface"
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);
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this.assertEqual(
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foo.pubf(),
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pub,
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"Public methods are accessible via public interface"
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);
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},
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/**
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* For reasons that are discussed in the next test (writing to public
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* properties), we need to make sure public members are available
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* internally. Actually, we don't need to test public methods, really, but
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* it's in there for good measure. Who knows what bugs may be introduced in
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* the future.
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*
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* This ensures that the getter is properly proxying the value to us.
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*/
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'Public members are accessible internally': function()
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{
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this.assertEqual(
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foo.getProp( 'pub' ),
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pub,
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"Public properties are accessible internally"
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);
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this.assertEqual(
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foo.getProp( 'pubf' )(),
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pub,
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"Public methods are accessible internally"
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);
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},
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/**
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* This may sound like an odd test, but it's actually very important. Due to
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* how private/protected members are implemented, it compromises public
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* members. In fact, public members would not work internally without what
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* is essentially a proxy via setters.
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*
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* This test is to ensure that the setter is properly forwarding writes to
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* the object within the prototype chain containing the public values.
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* Otherwise, setting the value would simply mask it in the prototype chain.
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* The value would appear to have changed internally, but when accessed
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* externally, the value would still be the same. That would obviously be a
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* problem ;)
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*/
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'Public properties are writable internally': function()
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{
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var val = 'moomookittypoo';
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// start by setting the value
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foo.setValue( 'pub', val );
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// we should see that change internally...
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this.assertEqual(
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foo.getProp( 'pub' ),
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val,
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"Setting the value of a public property internally should be " +
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"observable /internally/"
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);
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// ...as well as externally
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this.assertEqual(
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foo.pub,
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val,
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"Setting the value of a public property internally should be " +
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"observable /externally/"
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);
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},
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'Protected and private members are not accessible externally': function()
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{
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// browsers that do not support the property proxy will not support
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// encapsulating properties
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if ( util.definePropertyFallback() )
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{
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return;
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}
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this.assertEqual(
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foo.peeps,
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undefined,
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"Protected properties are inaccessible via public interface"
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);
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this.assertEqual(
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foo.parts,
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undefined,
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"Private properties are inaccessible via public interface"
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);
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this.assertEqual(
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foo.protf,
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undefined,
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"Protected methods are inaccessible via public interface"
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);
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this.assertEqual(
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foo.privf,
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undefined,
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"Private methods are inaccessible via public interface"
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);
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},
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/**
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* Protected members should be accessible from within class methods
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*/
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'Protected members are accessible internally': function()
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{
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this.assertEqual(
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foo.getProp( 'peeps' ),
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prot,
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"Protected properties are available internally"
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);
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// invoke rather than checking for equality, because the method may be
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// wrapped
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this.assertEqual(
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foo.getProp( 'protf' )(),
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prot,
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"Protected methods are available internally"
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);
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},
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/**
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* Private members should be accessible from within class methods
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*/
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'Private members are accessible internally': function()
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{
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this.assertEqual(
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foo.getProp( 'parts' ),
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priv,
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"Private properties are available internally"
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);
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// invoke rather than checking for equality, because the method may be
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// wrapped
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this.assertEqual(
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foo.getProp( 'privf' )(),
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priv,
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"Private methods are available internally"
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);
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},
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/**
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* Inheritance 101; protected members should be available to subtypes
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*/
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'Protected members are inherited from parent': function()
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{
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this.assertEqual(
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sub_foo.getProp( 'peeps' ),
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prot,
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"Protected properties are available to subtypes"
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);
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// invoke rather than checking for equality, because the method may be
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// wrapped
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this.assertEqual(
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sub_foo.getProp( 'protf' )(),
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prot,
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"Protected methods are available to subtypes"
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);
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},
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/**
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* Interface 101-2: We do not want private members to be available to
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* subtypes.
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*/
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'Private members of supertypes are inaccessible to subtypes': function()
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{
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// browsers that do not support the property proxy will not support
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// encapsulating properties
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if ( util.definePropertyFallback() )
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{
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return;
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}
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this.assertEqual(
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sub_foo.getProp( 'parts' ),
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undefined,
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"Private properties of supertypes should be unavailable to subtypes"
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);
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// invoke rather than checking for equality, because the method may be
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// wrapped
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this.assertEqual(
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sub_foo.getProp( 'privf' ),
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undefined,
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"Private methods of supertypes should be unavailable to subtypes"
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);
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},
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/**
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* For good measure, let's make sure we didn't screw anything up. To ensure
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* that the same object isn't being passed around to subtypes, ensure that
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* multiple class instances do not share prototypes.
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*/
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'Protected members are not shared between class instances': function()
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{
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var val = 'foobar';
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foo.setValue( 'prot', val );
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// ensure that class instances do not share values (ensuring the same
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// object isn't somehow being passed around)
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this.assertNotEqual(
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sub_foo.getProp( 'prot' ),
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val,
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"Class instances do not share protected values (subtype)"
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);
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// do the same for multiple instances of the same type
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var sub_foo2 = SubFoo();
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sub_foo2.setValue( 'prot', val );
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this.assertNotEqual(
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sub_foo.getProp( 'prot' ),
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val,
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"Class instances do not share protected values (same type)"
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);
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},
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/**
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* When a method is called, 'this' is bound to the property object
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* containing private and protected members. Returning 'this' would
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* therefore be a very bad thing. Not only would it break encapsulation, but
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* it would likely have other problems down the road.
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*
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* Therefore, we have to check the return value of the method. If the return
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* value is the property object that it was bound to, we need to replace the
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* return value with the actual class instance. This allows us to
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* transparently enforce encapsulation. How sweet is that?
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*/
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'Returning self from method should return instance not prop obj': function()
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{
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this.assertDeepEqual(
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foo.getSelf(),
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foo,
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"Returning 'this' from a method should return instance of self"
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);
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// what happens in the case of inheritance?
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this.assertDeepEqual(
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sub_foo.getSelf(),
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sub_foo,
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"Returning 'this' from a super method should return the subtype"
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);
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// finally, overridden methods should still return the instance
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this.assertDeepEqual(
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sub_foo.getSelfOverride(),
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sub_foo,
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"Returning 'this' from a overridden method should return subtype"
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);
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},
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/**
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* This one's a particularly nasty bug that snuck up on me. Private members
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* should not be accessible to subtypes; that's a given. However, they need
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* to be accessible to the parent methods. For example, let's say class Foo
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* contains public method bar(), which invokes private method _baz(). This
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* is perfectly legal. Then SubFoo extends Foo, but does not override method
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* bar(). Invoking method bar() should still be able to invoke private
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* method _baz(), because, from the perspective of the parent class, that
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* operation is perfectly legal.
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*
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* The resolution of this bug required a slight system redesign. The
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* short-term fix was to declare any needed private members are protected,
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* so that they were accessible by the subtype.
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*/
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'Parent methods can access private members of parent': function()
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{
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// properties
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this.assertEqual(
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sub_foo.getPrivProp(),
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priv,
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"Parent methods should have access to the private properties of " +
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"the parent"
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);
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// methods
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this.assertEqual(
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sub_foo.invokePriv(),
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priv,
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"Parent methods should have access to the private methods of the " +
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"parent"
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);
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// should apply to super-supertypes too
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this.assertEqual(
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sub_sub_foo.getPrivProp(),
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priv,
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"Parent methods should have access to the private properties of " +
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"the parent (2)"
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);
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this.assertEqual(
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sub_sub_foo.invokePriv(),
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priv,
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"Parent methods should have access to the private methods of the " +
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"parent (2)"
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);
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},
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/**
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* When a parent method is invoked, the parent should not be given access to
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* the private members of the invoking subtype. Why?
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*
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* This is not a matter of whether or not this is possible to do. In fact
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* it's relatively simple to implement. The issue is whether or not it makes
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* sense. Consider a compiled language. Let's say Foo and SubFoo (as
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* defined in this test case) were written in C++. Should Foo have access to
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* a private property on SubFoo when it is overridden?
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*
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* No - that doesn't make sense. The private member is not a member of Foo
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* and therefore Foo would fail to even compile. Alright, but we don't have
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* such a restriction in our case. So why not implement it?
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*
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* Proponents of such an implementation are likely thinking of the act of
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* inheriting methods as a copy/paste type of scenario. If we inherit public
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* method baz(), and it were a copy/paste type of situation, then surely
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* baz() would have access to all of SubFoo's private members. But that is
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* not the case. Should baz() be defined as a member of Foo, then its scope
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* is restricted to Foo and its supertypes. That is not how OO works. It is
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* /not/ copy/paste. It is inheriting functionality.
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*/
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'Parents should not have access to private members of subtypes': function()
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{
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// browsers that do not support the property proxy will not support
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// encapsulating properties
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if ( util.definePropertyFallback() )
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{
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return;
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}
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// property
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this.assertEqual(
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sub_foo.nonOverrideGetProp( '_pfoo' ),
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undefined,
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"Parent should not have access to private properties of subtype " +
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"whena parent method is invoked"
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);
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// member
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this.assertEqual(
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sub_foo.nonOverrideGetProp( '_myOwnPrivateFoo' ),
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undefined,
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"Parent should not have access to private methods of subtype " +
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"when a parent method is invoked"
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);
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},
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/**
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* Visibility escalation (protected -> private) should be permitted
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*/
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'Can escalate member visibility': function()
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{
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// escalate
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this.assertDoesNotThrow( function()
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{
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Class(
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{
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'protected foo': 'bar',
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'virtual protected baz': function() {},
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} ).extend( {
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'public foo': 'bar',
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'override public baz': function() {},
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} );
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}, Error, "Can escalate visibility of subtype members" );
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// same level of visibility
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this.assertDoesNotThrow( function()
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{
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Class(
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{
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'protected foo': 'bar',
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'virtual protected baz': function() {},
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} ).extend( {
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'protected foo': 'bar',
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'override protected baz': function() {},
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} );
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}, Error, "Can retain level of visibility for subtype members" );
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},
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|
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/**
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* We should /not/ be able to de-escalate member visibility
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* (public -> {protected,private}
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*/
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'Cannot de-escalate member visibility': function()
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{
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// public -> protected
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this.assertThrows( function()
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{
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Class(
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{
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'public foo': 'bar',
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} ).extend( {
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'protected foo': 'bar',
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} );
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}, Error, "Cannot de-escalate visibility of sub-props to protected" );
|
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this.assertThrows( function()
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{
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Class(
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{
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'virtual public baz': function() {},
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} ).extend( {
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'protected baz': function() {},
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} );
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}, Error, "Cannot de-escalate visibility of sub-methods to protected" );
|
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|
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// public -> private
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this.assertThrows( function()
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{
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Class(
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{
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'public foo': 'bar',
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} ).extend( {
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'private foo': 'bar',
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} );
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}, Error, "Cannot de-escalate visibility of subtype props to private" );
|
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this.assertThrows( function()
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{
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Class(
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{
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'virtual public baz': function() {},
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} ).extend( {
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'private baz': function() {},
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} );
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}, Error, "Cannot de-escalate visibility of sub-methods to private" );
|
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|
|
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// protected -> private
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this.assertThrows( function()
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{
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Class(
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{
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'protected foo': 'bar',
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} ).extend( {
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'private foo': 'bar',
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} );
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}, Error, "Cannot de-escalate visibility of sub-props to private2" );
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this.assertThrows( function()
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{
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Class(
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{
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'virtual protected baz': function() {},
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} ).extend( {
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'private baz': function() {},
|
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} );
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}, Error, "Cannot de-escalate visibility of sub-methods to private2" );
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},
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|
|
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/**
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|
* With the visibility implementation, it's possible that __super() will not
|
|
* work properly with protected methods. This is because of the override
|
|
* lookup process (which hopefully was fixed in the commit before this test
|
|
* was originally introduced: ce736bea).
|
|
*/
|
|
'Calling super method works properly with protected methods': function()
|
|
{
|
|
var val = 'foobar',
|
|
result = Class( {
|
|
'virtual protected foo': function()
|
|
{
|
|
return val;
|
|
},
|
|
} ).extend(
|
|
{
|
|
// we override to public just so we can call it externally
|
|
'override public foo': function()
|
|
{
|
|
return this.__super();
|
|
},
|
|
} )().foo();
|
|
|
|
this.assertEqual( result, val,
|
|
"__super() calls work with protected overrides"
|
|
);
|
|
},
|
|
|
|
|
|
/**
|
|
* Concrete implementations of interfaces should have to follow the same
|
|
* visibility de-escalation rules as defined in the above tests (otherwise,
|
|
* that defeats the purpose of an interface). In other words, they must be
|
|
* public.
|
|
*/
|
|
'Visibility de-escalation rulse apply to interfaces': function()
|
|
{
|
|
this.assertThrows( function()
|
|
{
|
|
Class.implement( Interface( { 'abstract public foo': [] } ) )
|
|
.extend(
|
|
{
|
|
// should throw an exception; visibility de-escalation
|
|
'protected foo': function() {},
|
|
}
|
|
);
|
|
}, Error, "Cannot de-escalate visibility for interface members" );
|
|
},
|
|
|
|
|
|
/**
|
|
* Due to the way the property object is laid atop of the public members, we
|
|
* need to ensure that protected methods' functionality can /actually/ be
|
|
* overridden, since the protected method is higher in the prototype chain
|
|
* and therefore will be accessed before the public method.
|
|
*
|
|
* We don't care about private -> protected, because that's not possible
|
|
* through inheritance.
|
|
*/
|
|
'Can override protected method functionality with public': function()
|
|
{
|
|
// get the result of invoking overridden foo()
|
|
var result = Class(
|
|
{
|
|
'virtual protected foo': function()
|
|
{
|
|
return false;
|
|
},
|
|
} ).extend(
|
|
{
|
|
// override and escalate visibility of method foo()
|
|
'override public foo': function()
|
|
{
|
|
return true;
|
|
},
|
|
} )().foo();
|
|
|
|
// if the override was successful, we'll be able to invoke the
|
|
// overridden method
|
|
this.assertEqual( result, true,
|
|
"Can properly override protected methods with public"
|
|
);
|
|
},
|
|
|
|
|
|
/**
|
|
* There was an issue where the private property object was not proxying
|
|
* values to the true protected values. This would mean that when the parent
|
|
* initialized protected values, those values would be unavailable to the
|
|
* subtype. Instead, the value available to the subtype was the value that
|
|
* was assigned as the default value in the class definition.
|
|
*/
|
|
'Protected values are available to subtypes when set by parent': function()
|
|
{
|
|
var expected = 5,
|
|
result = Class(
|
|
{
|
|
'protected val': 0,
|
|
|
|
'public __construct': function()
|
|
{
|
|
this.val = expected;
|
|
},
|
|
} ).extend(
|
|
{
|
|
'public getVal': function()
|
|
{
|
|
return this.val;
|
|
},
|
|
} )().getVal();
|
|
|
|
this.assertEqual( result, expected,
|
|
"Subtypes should have acess to protected properties values set " +
|
|
"by super methods"
|
|
);
|
|
},
|
|
|
|
|
|
/**
|
|
* There was a bug introduced when we prevented protected members from
|
|
* overriding public (since in the prototype chain, protected members are
|
|
* laid atop public, and this cannot change). This bug would disallow
|
|
* protected members from being overridden by other protected members.
|
|
*
|
|
* This test is both a proof and a regression test.
|
|
*/
|
|
'Can properly override protected with protected': function()
|
|
{
|
|
var val = 'foobar',
|
|
result = Class(
|
|
{
|
|
'virtual protected foo': function() {},
|
|
} ).extend(
|
|
{
|
|
// provide concrete implementation
|
|
'override protected foo': function()
|
|
{
|
|
return val;
|
|
},
|
|
|
|
'public doFoo': function()
|
|
{
|
|
return this.foo();
|
|
},
|
|
} )().doFoo();
|
|
;
|
|
|
|
// if everything worked as expected, the value of 'val' will have been
|
|
// returned and stored in 'result'
|
|
this.assertEqual( result, val,
|
|
"Protected methods can properly be overriden by another " +
|
|
"protected method"
|
|
);
|
|
},
|
|
} );
|
|
|