Add a way to exclude categories from Special:UnusedCategories

Added __EXPECT_UNUSED_CATEGORY__ as a behavioral switch. Adding
this switch to category pages prevents them from appearing in
Special:UnusedCategories.

Bug: T96041
Change-Id: I055e59f5311347155e0f801dd5ec9a6d4a68c9cc

6 files changed, 71 insertions, 4 deletions

diff --git a/RELEASE-NOTES-1.33 b/RELEASE-NOTES-1.33
index c573a5951cff..df6b5f821479 100644
--- a/RELEASE-NOTES-1.33
+++ b/RELEASE-NOTES-1.33
@@ -30,6 +30,8 @@ production.
 
 === New features in 1.33 ===
 * The 'GetPreferences' hook now receives an additional $context parameter.
+* (T96041) __EXPECT_UNUSED_CATEGORY__ on a category page causes the category
+  to be hidden on Special:UnusedCategories.
 * …
 
 === External library changes in 1.33 ===
diff --git a/includes/MagicWordFactory.php b/includes/MagicWordFactory.php
index e62716d67e32..4e9bfaf1f7e7 100644
--- a/includes/MagicWordFactory.php
+++ b/includes/MagicWordFactory.php
@@ -173,6 +173,7 @@ class MagicWordFactory {
 		'newsectionlink',
 		'nonewsectionlink',
 		'hiddencat',
+		'expectunusedcategory',
 		'index',
 		'noindex',
 		'staticredirect',
diff --git a/includes/page/WikiCategoryPage.php b/includes/page/WikiCategoryPage.php
index 6c932029ae2c..283757399861 100644
--- a/includes/page/WikiCategoryPage.php
+++ b/includes/page/WikiCategoryPage.php
@@ -59,6 +59,20 @@ class WikiCategoryPage extends WikiPage {
 		$pageId = $this->getTitle()->getArticleID();
 		$pageProps = PageProps::getInstance()->getProperties( $this->getTitle(), 'hiddencat' );
 
-		return isset( $pageProps[$pageId] ) ? true : false;
+		return isset( $pageProps[$pageId] );
+	}
+
+	/**
+	 * Checks if a category is expected to be an unused category.
+	 *
+	 * @since 1.33
+	 *
+	 * @return bool
+	 */
+	public function isExpectedUnusedCategory() {
+		$pageId = $this->getTitle()->getArticleID();
+		$pageProps = PageProps::getInstance()->getProperties( $this->getTitle(), 'expectunusedcategory' );
+
+		return isset( $pageProps[$pageId] );
 	}
 }
diff --git a/includes/specials/SpecialUnusedcategories.php b/includes/specials/SpecialUnusedcategories.php
index 1469742a4b8b..2577a100cf9f 100644
--- a/includes/specials/SpecialUnusedcategories.php
+++ b/includes/specials/SpecialUnusedcategories.php
@@ -39,7 +39,7 @@ class UnusedCategoriesPage extends QueryPage {
 
 	public function getQueryInfo() {
 		return [
-			'tables' => [ 'page', 'categorylinks' ],
+			'tables' => [ 'page', 'categorylinks', 'page_props' ],
 			'fields' => [
 				'namespace' => 'page_namespace',
 				'title' => 'page_title',
@@ -48,9 +48,16 @@ class UnusedCategoriesPage extends QueryPage {
 			'conds' => [
 				'cl_from IS NULL',
 				'page_namespace' => NS_CATEGORY,
-				'page_is_redirect' => 0
+				'page_is_redirect' => 0,
+				'pp_page IS NULL'
 			],
-			'join_conds' => [ 'categorylinks' => [ 'LEFT JOIN', 'cl_to = page_title' ] ]
+			'join_conds' => [
+				'categorylinks' => [ 'LEFT JOIN', 'cl_to = page_title' ],
+				'page_props' => [ 'LEFT JOIN', [
+					'page_id = pp_page',
+					'pp_propname' => 'expectunusedcategory'
+				] ]
+			]
 		];
 	}
 
diff --git a/languages/messages/MessagesEn.php b/languages/messages/MessagesEn.php
index 587f6ea4adb4..b5e2c5eaa7da 100644
--- a/languages/messages/MessagesEn.php
+++ b/languages/messages/MessagesEn.php
@@ -359,6 +359,7 @@ $magicWords = [
 	'filepath'                => [ 0, 'FILEPATH:' ],
 	'tag'                     => [ 0, 'tag' ],
 	'hiddencat'               => [ 1, '__HIDDENCAT__' ],
+	'expectunusedcategory'    => [ 1, '__EXPECT_UNUSED_CATEGORY__', '__EXPECT_UNUSED_CAT__', '__EXPECTUNUSEDCATEGORY__', '__EXPECTUNUSEDCAT__' ],
 	'pagesincategory'         => [ 1, 'PAGESINCATEGORY', 'PAGESINCAT' ],
 	'pagesize'                => [ 1, 'PAGESIZE' ],
 	'index'                   => [ 1, '__INDEX__' ],
diff --git a/tests/phpunit/includes/page/WikiCategoryPageTest.php b/tests/phpunit/includes/page/WikiCategoryPageTest.php
index 5f1bf0ca794a..9f696c08b834 100644
--- a/tests/phpunit/includes/page/WikiCategoryPageTest.php
+++ b/tests/phpunit/includes/page/WikiCategoryPageTest.php
@@ -60,4 +60,46 @@ class WikiCategoryPageTest extends MediaWikiLangTestCase {
 
 		ScopedCallback::consume( $scopedOverride );
 	}
+
+	/**
+	 * @covers WikiCategoryPage::isExpectedUnusedCategory
+	 */
+	public function testExpectUnusedCategory_PropertyNotSet() {
+		$title = Title::makeTitle( NS_CATEGORY, 'CategoryPage' );
+		$categoryPage = WikiCategoryPage::factory( $title );
+
+		$pageProps = $this->getMockPageProps();
+		$pageProps->expects( $this->once() )
+			->method( 'getProperties' )
+			->with( $title, 'expectunusedcategory' )
+			->will( $this->returnValue( [] ) );
+
+		$scopedOverride = PageProps::overrideInstance( $pageProps );
+
+		$this->assertFalse( $categoryPage->isExpectedUnusedCategory() );
+
+		ScopedCallback::consume( $scopedOverride );
+	}
+
+	/**
+	 * @dataProvider provideCategoryContent
+	 * @covers WikiCategoryPage::isExpectedUnusedCategory
+	 */
+	public function testExpectUnusedCategory_PropertyIsSet( $isExpectedUnusedCategory ) {
+		$categoryTitle = Title::makeTitle( NS_CATEGORY, 'CategoryPage' );
+		$categoryPage = WikiCategoryPage::factory( $categoryTitle );
+		$returnValue = $isExpectedUnusedCategory ? [ $categoryTitle->getArticleID() => '' ] : [];
+
+		$pageProps = $this->getMockPageProps();
+		$pageProps->expects( $this->once() )
+			->method( 'getProperties' )
+			->with( $categoryTitle, 'expectunusedcategory' )
+			->will( $this->returnValue( $returnValue ) );
+
+		$scopedOverride = PageProps::overrideInstance( $pageProps );
+
+		$this->assertEquals( $isExpectedUnusedCategory, $categoryPage->isExpectedUnusedCategory() );
+
+		ScopedCallback::consume( $scopedOverride );
+	}
 }