Merge "mediawiki.Title: Add isTalkPage/getTalkPage methods to mw.Title.js"

diff --combined resources/src/mediawiki.Title/Title.js
index 33e5fbf,b80928d..0bcb2b6
--- 1/resources/src/mediawiki.Title/Title.js
--- 2/resources/src/mediawiki.Title/Title.js
+++ b/resources/src/mediawiki.Title/Title.js
@@@ -4,7 -4,7 +4,7 @@@
   * @since 1.18
   */
  
 -( function ( mw, $ ) {
 +( function () {
        /**
         * Parse titles into an object structure. Note that when using the constructor
         * directly, passing invalid titles will result in an exception. Use #newFromText to use the
@@@ -662,12 -662,22 +662,22 @@@
                return null;
        };
  
+       /**
+        * Check if a given namespace is a talk namespace
+        * @param {number} namespaceId Namespace ID
+        * @return {boolean} Namespace is a talk namespace
+        */
+       Title.isTalkNamespace = function ( namespaceId ) {
+               return !!( namespaceId > NS_MAIN && namespaceId % 2 );
+       };
+ 
        /**
         * Whether this title exists on the wiki.
         *
         * @static
         * @param {string|mw.Title} title prefixed db-key name (string) or instance of Title
         * @return {boolean|null} Boolean if the information is available, otherwise null
+        * @throws {Error} If title is not a string or mw.Title
         */
        Title.exists = function ( title ) {
                var match,
@@@ -931,6 -941,49 +941,49 @@@
                        }
                },
  
+               /**
+                * Check if the title is in a talk namespace
+                *
+                * @return {boolean} The title is in a talk namespace
+                */
+               isTalkPage: function () {
+                       return Title.isTalkNamespace( this.getNamespaceId() );
+               },
+ 
+               /**
+                * Get the title for the associated talk page
+                *
+                * @return {mw.Title|null} The title for the associated talk page, null if not available
+                */
+               getTalkPage: function () {
+                       if ( !this.canHaveTalkPage() ) {
+                               return null;
+                       }
+                       return this.isTalkPage() ?
+                               this :
+                               Title.makeTitle( this.getNamespaceId() + 1, this.getMainText() );
+               },
+ 
+               /**
+                * Get the title for the subject page of a talk page
+                *
+                * @return {mw.Title|null} The title for the subject page of a talk page, null if not available
+                */
+               getSubjectPage: function () {
+                       return this.isTalkPage() ?
+                               Title.makeTitle( this.getNamespaceId() - 1, this.getMainText() ) :
+                               this;
+               },
+ 
+               /**
+                * Check the the title can have an associated talk page
+                *
+                * @return {boolean} The title can have an associated talk page
+                */
+               canHaveTalkPage: function () {
+                       return this.getNamespaceId() >= NS_MAIN;
+               },
+ 
                /**
                 * Whether this title exists on the wiki.
                 *
@@@ -957,4 -1010,4 +1010,4 @@@
        // Expose
        mw.Title = Title;
  
 -}( mediaWiki, jQuery ) );
 +}() );

diff --combined tests/qunit/suites/resources/mediawiki/mediawiki.Title.test.js
index 44c1f4b,ea278f7..acdf2f1
--- 1/tests/qunit/suites/resources/mediawiki/mediawiki.Title.test.js
--- 2/tests/qunit/suites/resources/mediawiki/mediawiki.Title.test.js
+++ b/tests/qunit/suites/resources/mediawiki/mediawiki.Title.test.js
@@@ -1,4 -1,4 +1,4 @@@
 -( function ( mw, $ ) {
 +( function () {
        /* eslint-disable camelcase */
        var repeat = function ( input, multiplier ) {
                        return new Array( multiplier + 1 ).join( input );
@@@ -291,6 -291,38 +291,38 @@@
                assert.strictEqual( title.toString(), 'Penguins:Flightless_yet_cute.jpg' );
        } );
  
+       QUnit.test( 'isTalkPage/getTalkPage/getSubjectPage', function ( assert ) {
+               var title;
+ 
+               title = new mw.Title( 'User:Foo' );
+               assert.strictEqual( title.isTalkPage(), false, 'Non-talk page detected as such' );
+               assert.strictEqual( title.getSubjectPage().getPrefixedText(), 'User:Foo', 'getSubjectPage on a subject page is a no-op' );
+ 
+               title = title.getTalkPage();
+               assert.strictEqual( title.getPrefixedText(), 'User talk:Foo', 'getTalkPage creates correct title' );
+               assert.strictEqual( title.getTalkPage().getPrefixedText(), 'User talk:Foo', 'getTalkPage on a talk page is a no-op' );
+               assert.strictEqual( title.isTalkPage(), true, 'Talk page is detected as such' );
+ 
+               title = title.getSubjectPage();
+               assert.strictEqual( title.getPrefixedText(), 'User:Foo', 'getSubjectPage creates correct title' );
+ 
+               title = new mw.Title( 'Special:AllPages' );
+               assert.strictEqual( title.isTalkPage(), false, 'Special page is not a talk page' );
+               assert.strictEqual( title.getTalkPage(), null, 'getTalkPage not valid for this namespace' );
+               assert.strictEqual( title.getSubjectPage().getPrefixedText(), 'Special:AllPages', 'getSubjectPage is self for special pages' );
+ 
+               title = new mw.Title( 'Category:Project:Maintenance' );
+               assert.strictEqual( title.getTalkPage().getPrefixedText(), 'Category talk:Project:Maintenance', 'getTalkPage is not confused by colon in main text' );
+               title = new mw.Title( 'Category talk:Project:Maintenance' );
+               assert.strictEqual( title.getSubjectPage().getPrefixedText(), 'Category:Project:Maintenance', 'getSubjectPage is not confused by colon in main text' );
+ 
+               title = new mw.Title( 'Foo#Caption' );
+               assert.strictEqual( title.getFragment(), 'Caption', 'Subject page has a fragment' );
+               title = title.getTalkPage();
+               assert.strictEqual( title.getPrefixedText(), 'Talk:Foo', 'getTalkPage creates correct title' );
+               assert.strictEqual( title.getFragment(), null, 'getTalkPage does not copy the fragment' );
+       } );
+ 
        QUnit.test( 'Throw error on invalid title', function ( assert ) {
                assert.throws( function () {
                        return new mw.Title( '' );
@@@ -735,4 -767,4 +767,4 @@@
                }
        } );
  
 -}( mediaWiki, jQuery ) );
 +}() );