MediaWiki/tests/phpunit/includes/Storage/DerivedPageDataUpdaterTest.php

<?php

namespace MediaWiki\Tests\Storage;

use CommentStoreComment;
use Content;
use ContentHandler;
use LinksUpdate;
use MediaWiki\MediaWikiServices;
use MediaWiki\Storage\DerivedPageDataUpdater;
use MediaWiki\Storage\MutableRevisionRecord;
use MediaWiki\Storage\MutableRevisionSlots;
use MediaWiki\Storage\RevisionRecord;
use MediaWiki\Storage\RevisionSlotsUpdate;
use MediaWiki\Storage\SlotRecord;
use MediaWikiTestCase;
use MWCallableUpdate;
use PHPUnit\Framework\MockObject\MockObject;
use TextContent;
use TextContentHandler;
use Title;
use User;
use Wikimedia\TestingAccessWrapper;
use WikiPage;
use WikitextContent;

/**
 * @group Database
 *
 * @covers \MediaWiki\Storage\DerivedPageDataUpdater
 */
class DerivedPageDataUpdaterTest extends MediaWikiTestCase {

	/**
	 * @param string $title
	 *
	 * @return Title
	 */
	private function getTitle( $title ) {
		return Title::makeTitleSafe( $this->getDefaultWikitextNS(), $title );
	}

	/**
	 * @param string|Title $title
	 *
	 * @return WikiPage
	 */
	private function getPage( $title ) {
		$title = ( $title instanceof Title ) ? $title : $this->getTitle( $title );

		return WikiPage::factory( $title );
	}

	/**
	 * @param string|Title|WikiPage $page
	 *
	 * @return DerivedPageDataUpdater
	 */
	private function getDerivedPageDataUpdater( $page, RevisionRecord $rec = null ) {
		if ( is_string( $page ) || $page instanceof Title ) {
			$page = $this->getPage( $page );
		}

		$page = TestingAccessWrapper::newFromObject( $page );
		return $page->getDerivedDataUpdater( null, $rec );
	}

	/**
	 * Creates a revision in the database.
	 *
	 * @param WikiPage $page
	 * @param $summary
	 * @param null|string|Content $content
	 *
	 * @return RevisionRecord|null
	 */
	private function createRevision( WikiPage $page, $summary, $content = null ) {
		$user = $this->getTestUser()->getUser();
		$comment = CommentStoreComment::newUnsavedComment( $summary );

		if ( $content === null || is_string( $content ) ) {
			$content = new WikitextContent( $content ?? $summary );
		}

		if ( !is_array( $content ) ) {
			$content = [ 'main' => $content ];
		}

		$this->getDerivedPageDataUpdater( $page ); // flush cached instance before.

		$updater = $page->newPageUpdater( $user );

		foreach ( $content as $role => $c ) {
			$updater->setContent( $role, $c );
		}

		$rev = $updater->saveRevision( $comment );

		$this->getDerivedPageDataUpdater( $page ); // flush cached instance after.
		return $rev;
	}

	// TODO: test setArticleCountMethod() and isCountable();
	// TODO: test isRedirect() and wasRedirect()

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getCanonicalParserOptions()
	 */
	public function testGetCanonicalParserOptions() {
		$user = $this->getTestUser()->getUser();
		$page = $this->getPage( __METHOD__ );

		$parentRev = $this->createRevision( $page, 'first' );

		$mainContent = new WikitextContent( 'Lorem ipsum' );

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent );
		$updater = $this->getDerivedPageDataUpdater( $page );
		$updater->prepareContent( $user, $update, false );

		$options1 = $updater->getCanonicalParserOptions();
		$this->assertSame( MediaWikiServices::getInstance()->getContentLanguage(),
			$options1->getUserLangObj() );

		$speculativeId = $options1->getSpeculativeRevId();
		$this->assertSame( $parentRev->getId() + 1, $speculativeId );

		$rev = $this->makeRevision(
			$page->getTitle(),
			$update,
			$user,
			$parentRev->getId() + 7,
			$parentRev->getId()
		);
		$updater->prepareUpdate( $rev );

		$options2 = $updater->getCanonicalParserOptions();

		$currentRev = call_user_func( $options2->getCurrentRevisionCallback(), $page->getTitle() );
		$this->assertSame( $rev->getId(), $currentRev->getId() );
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::grabCurrentRevision()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::pageExisted()
	 */
	public function testGrabCurrentRevision() {
		$page = $this->getPage( __METHOD__ );

		$updater0 = $this->getDerivedPageDataUpdater( $page );
		$this->assertNull( $updater0->grabCurrentRevision() );
		$this->assertFalse( $updater0->pageExisted() );

		$rev1 = $this->createRevision( $page, 'first' );
		$updater1 = $this->getDerivedPageDataUpdater( $page );
		$this->assertSame( $rev1->getId(), $updater1->grabCurrentRevision()->getId() );
		$this->assertFalse( $updater0->pageExisted() );
		$this->assertTrue( $updater1->pageExisted() );

		$rev2 = $this->createRevision( $page, 'second' );
		$updater2 = $this->getDerivedPageDataUpdater( $page );
		$this->assertSame( $rev1->getId(), $updater1->grabCurrentRevision()->getId() );
		$this->assertSame( $rev2->getId(), $updater2->grabCurrentRevision()->getId() );
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::prepareContent()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isContentPrepared()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::pageExisted()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isCreation()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isChange()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getSlots()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getRawSlot()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getRawContent()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getModifiedSlotRoles()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getTouchedSlotRoles()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getSlotParserOutput()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getCanonicalParserOutput()
	 */
	public function testPrepareContent() {
		$sysop = $this->getTestUser( [ 'sysop' ] )->getUser();
		$updater = $this->getDerivedPageDataUpdater( __METHOD__ );

		$this->assertFalse( $updater->isContentPrepared() );

		// TODO: test stash
		// TODO: MCR: Test multiple slots. Test slot removal.
		$mainContent = new WikitextContent( 'first [[main]] ~~~' );
		$auxContent = new WikitextContent( 'inherited ~~~ content' );
		$auxSlot = SlotRecord::newSaved(
			10, 7, 'tt:7',
			SlotRecord::newUnsaved( 'aux', $auxContent )
		);

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent );
		$update->modifySlot( SlotRecord::newInherited( $auxSlot ) );
		// TODO: MCR: test removing slots!

		$updater->prepareContent( $sysop, $update, false );

		// second be ok to call again with the same params
		$updater->prepareContent( $sysop, $update, false );

		$this->assertNull( $updater->grabCurrentRevision() );
		$this->assertTrue( $updater->isContentPrepared() );
		$this->assertFalse( $updater->isUpdatePrepared() );
		$this->assertFalse( $updater->pageExisted() );
		$this->assertTrue( $updater->isCreation() );
		$this->assertTrue( $updater->isChange() );
		$this->assertFalse( $updater->isContentDeleted() );

		$this->assertNotNull( $updater->getRevision() );
		$this->assertNotNull( $updater->getRenderedRevision() );

		$this->assertEquals( [ 'main', 'aux' ], $updater->getSlots()->getSlotRoles() );
		$this->assertEquals( [ 'main' ], array_keys( $updater->getSlots()->getOriginalSlots() ) );
		$this->assertEquals( [ 'aux' ], array_keys( $updater->getSlots()->getInheritedSlots() ) );
		$this->assertEquals( [ 'main', 'aux' ], $updater->getModifiedSlotRoles() );
		$this->assertEquals( [ 'main', 'aux' ], $updater->getTouchedSlotRoles() );

		$mainSlot = $updater->getRawSlot( 'main' );
		$this->assertInstanceOf( SlotRecord::class, $mainSlot );
		$this->assertNotContains( '~~~', $mainSlot->getContent()->serialize(), 'PST should apply.' );
		$this->assertContains( $sysop->getName(), $mainSlot->getContent()->serialize() );

		$auxSlot = $updater->getRawSlot( 'aux' );
		$this->assertInstanceOf( SlotRecord::class, $auxSlot );
		$this->assertContains( '~~~', $auxSlot->getContent()->serialize(), 'No PST should apply.' );

		$mainOutput = $updater->getCanonicalParserOutput();
		$this->assertContains( 'first', $mainOutput->getText() );
		$this->assertContains( '<a ', $mainOutput->getText() );
		$this->assertNotEmpty( $mainOutput->getLinks() );

		$canonicalOutput = $updater->getCanonicalParserOutput();
		$this->assertContains( 'first', $canonicalOutput->getText() );
		$this->assertContains( '<a ', $canonicalOutput->getText() );
		$this->assertContains( 'inherited ', $canonicalOutput->getText() );
		$this->assertNotEmpty( $canonicalOutput->getLinks() );
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::prepareContent()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::pageExisted()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isCreation()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isChange()
	 */
	public function testPrepareContentInherit() {
		$sysop = $this->getTestUser( [ 'sysop' ] )->getUser();
		$page = $this->getPage( __METHOD__ );

		$mainContent1 = new WikitextContent( 'first [[main]] ({{REVISIONUSER}}) #~~~#' );
		$mainContent2 = new WikitextContent( 'second ({{subst:REVISIONUSER}}) #~~~#' );

		$rev = $this->createRevision( $page, 'first', $mainContent1 );
		$mainContent1 = $rev->getContent( 'main' ); // get post-pst content
		$userName = $rev->getUser()->getName();
		$sysopName = $sysop->getName();

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent1 );
		$updater1 = $this->getDerivedPageDataUpdater( $page );
		$updater1->prepareContent( $sysop, $update, false );

		$this->assertNotNull( $updater1->grabCurrentRevision() );
		$this->assertTrue( $updater1->isContentPrepared() );
		$this->assertTrue( $updater1->pageExisted() );
		$this->assertFalse( $updater1->isCreation() );
		$this->assertFalse( $updater1->isChange() );

		$this->assertNotNull( $updater1->getRevision() );
		$this->assertNotNull( $updater1->getRenderedRevision() );

		// parser-output for null-edit uses the original author's name
		$html = $updater1->getRenderedRevision()->getRevisionParserOutput()->getText();
		$this->assertNotContains( $sysopName, $html, '{{REVISIONUSER}}' );
		$this->assertNotContains( '{{REVISIONUSER}}', $html, '{{REVISIONUSER}}' );
		$this->assertNotContains( '~~~', $html, 'signature ~~~' );
		$this->assertContains( '(' . $userName . ')', $html, '{{REVISIONUSER}}' );
		$this->assertContains( '>' . $userName . '<', $html, 'signature ~~~' );

		// TODO: MCR: test inheritance from parent
		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent2 );
		$updater2 = $this->getDerivedPageDataUpdater( $page );
		$updater2->prepareContent( $sysop, $update, false );

		// non-null edit use the new user name in PST
		$pstText = $updater2->getSlots()->getContent( 'main' )->serialize();
		$this->assertNotContains( '{{subst:REVISIONUSER}}', $pstText, '{{subst:REVISIONUSER}}' );
		$this->assertNotContains( '~~~', $pstText, 'signature ~~~' );
		$this->assertContains( '(' . $sysopName . ')', $pstText, '{{subst:REVISIONUSER}}' );
		$this->assertContains( ':' . $sysopName . '|', $pstText, 'signature ~~~' );

		$this->assertFalse( $updater2->isCreation() );
		$this->assertTrue( $updater2->isChange() );
	}

	// TODO: test failure of prepareContent() when called again...
	// - with different user
	// - with different update
	// - after calling prepareUpdate()

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::prepareUpdate()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isUpdatePrepared()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isCreation()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getSlots()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getRawSlot()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getRawContent()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getModifiedSlotRoles()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getTouchedSlotRoles()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getSlotParserOutput()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getCanonicalParserOutput()
	 */
	public function testPrepareUpdate() {
		$page = $this->getPage( __METHOD__ );

		$mainContent1 = new WikitextContent( 'first [[main]] ~~~' );
		$rev1 = $this->createRevision( $page, 'first', $mainContent1 );
		$updater1 = $this->getDerivedPageDataUpdater( $page, $rev1 );

		$options = []; // TODO: test *all* the options...
		$updater1->prepareUpdate( $rev1, $options );

		$this->assertTrue( $updater1->isUpdatePrepared() );
		$this->assertTrue( $updater1->isContentPrepared() );
		$this->assertTrue( $updater1->isCreation() );
		$this->assertTrue( $updater1->isChange() );
		$this->assertFalse( $updater1->isContentDeleted() );

		$this->assertNotNull( $updater1->getRevision() );
		$this->assertNotNull( $updater1->getRenderedRevision() );

		$this->assertEquals( [ 'main' ], $updater1->getSlots()->getSlotRoles() );
		$this->assertEquals( [ 'main' ], array_keys( $updater1->getSlots()->getOriginalSlots() ) );
		$this->assertEquals( [], array_keys( $updater1->getSlots()->getInheritedSlots() ) );
		$this->assertEquals( [ 'main' ], $updater1->getModifiedSlotRoles() );
		$this->assertEquals( [ 'main' ], $updater1->getTouchedSlotRoles() );

		// TODO: MCR: test multiple slots, test slot removal!

		$this->assertInstanceOf( SlotRecord::class, $updater1->getRawSlot( 'main' ) );
		$this->assertNotContains( '~~~~', $updater1->getRawContent( 'main' )->serialize() );

		$mainOutput = $updater1->getCanonicalParserOutput();
		$this->assertContains( 'first', $mainOutput->getText() );
		$this->assertContains( '<a ', $mainOutput->getText() );
		$this->assertNotEmpty( $mainOutput->getLinks() );

		$canonicalOutput = $updater1->getCanonicalParserOutput();
		$this->assertContains( 'first', $canonicalOutput->getText() );
		$this->assertContains( '<a ', $canonicalOutput->getText() );
		$this->assertNotEmpty( $canonicalOutput->getLinks() );

		$mainContent2 = new WikitextContent( 'second' );
		$rev2 = $this->createRevision( $page, 'second', $mainContent2 );
		$updater2 = $this->getDerivedPageDataUpdater( $page, $rev2 );

		$options = []; // TODO: test *all* the options...
		$updater2->prepareUpdate( $rev2, $options );

		$this->assertFalse( $updater2->isCreation() );
		$this->assertTrue( $updater2->isChange() );

		$canonicalOutput = $updater2->getCanonicalParserOutput();
		$this->assertContains( 'second', $canonicalOutput->getText() );
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::prepareUpdate()
	 */
	public function testPrepareUpdateReusesParserOutput() {
		$user = $this->getTestUser()->getUser();
		$page = $this->getPage( __METHOD__ );

		$mainContent1 = new WikitextContent( 'first [[main]] ~~~' );

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent1 );
		$updater = $this->getDerivedPageDataUpdater( $page );
		$updater->prepareContent( $user, $update, false );

		$mainOutput = $updater->getSlotParserOutput( 'main' );
		$canonicalOutput = $updater->getCanonicalParserOutput();

		$rev = $this->createRevision( $page, 'first', $mainContent1 );

		$options = []; // TODO: test *all* the options...
		$updater->prepareUpdate( $rev, $options );

		$this->assertTrue( $updater->isUpdatePrepared() );
		$this->assertTrue( $updater->isContentPrepared() );

		$this->assertSame( $mainOutput, $updater->getSlotParserOutput( 'main' ) );
		$this->assertSame( $canonicalOutput, $updater->getCanonicalParserOutput() );
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::prepareUpdate()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getSlotParserOutput()
	 */
	public function testPrepareUpdateOutputReset() {
		$user = $this->getTestUser()->getUser();
		$page = $this->getPage( __METHOD__ );

		$mainContent1 = new WikitextContent( 'first --{{REVISIONID}}--' );

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent1 );
		$updater = $this->getDerivedPageDataUpdater( $page );
		$updater->prepareContent( $user, $update, false );

		$mainOutput = $updater->getSlotParserOutput( 'main' );
		$canonicalOutput = $updater->getCanonicalParserOutput();

		// prevent optimization on matching speculative ID
		$mainOutput->setSpeculativeRevIdUsed( 0 );
		$canonicalOutput->setSpeculativeRevIdUsed( 0 );

		$rev = $this->createRevision( $page, 'first', $mainContent1 );

		$options = []; // TODO: test *all* the options...
		$updater->prepareUpdate( $rev, $options );

		$this->assertTrue( $updater->isUpdatePrepared() );
		$this->assertTrue( $updater->isContentPrepared() );

		// ParserOutput objects should have been flushed.
		$this->assertNotSame( $mainOutput, $updater->getSlotParserOutput( 'main' ) );
		$this->assertNotSame( $canonicalOutput, $updater->getCanonicalParserOutput() );

		$html = $updater->getCanonicalParserOutput()->getText();
		$this->assertContains( '--' . $rev->getId() . '--', $html );

		// TODO: MCR: ensure that when the main slot uses {{REVISIONID}} but another slot is
		// updated, the main slot is still re-rendered!
	}

	// TODO: test failure of prepareUpdate() when called again with a different revision
	// TODO: test failure of prepareUpdate() on inconsistency with prepareContent.

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getPreparedEdit()
	 */
	public function testGetPreparedEditAfterPrepareContent() {
		$user = $this->getTestUser()->getUser();

		$mainContent = new WikitextContent( 'first [[main]] ~~~' );
		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent );

		$updater = $this->getDerivedPageDataUpdater( __METHOD__ );
		$updater->prepareContent( $user, $update, false );

		$canonicalOutput = $updater->getCanonicalParserOutput();

		$preparedEdit = $updater->getPreparedEdit();
		$this->assertSame( $canonicalOutput->getCacheTime(), $preparedEdit->timestamp );
		$this->assertSame( $canonicalOutput, $preparedEdit->output );
		$this->assertSame( $mainContent, $preparedEdit->newContent );
		$this->assertSame( $updater->getRawContent( 'main' ), $preparedEdit->pstContent );
		$this->assertSame( $updater->getCanonicalParserOptions(), $preparedEdit->popts );
		$this->assertSame( null, $preparedEdit->revid );
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::getPreparedEdit()
	 */
	public function testGetPreparedEditAfterPrepareUpdate() {
		$page = $this->getPage( __METHOD__ );

		$mainContent = new WikitextContent( 'first [[main]] ~~~' );
		$update = new MutableRevisionSlots();
		$update->setContent( 'main', $mainContent );

		$rev = $this->createRevision( $page, __METHOD__ );

		$updater = $this->getDerivedPageDataUpdater( $page );
		$updater->prepareUpdate( $rev );

		$canonicalOutput = $updater->getCanonicalParserOutput();

		$preparedEdit = $updater->getPreparedEdit();
		$this->assertSame( $canonicalOutput->getCacheTime(), $preparedEdit->timestamp );
		$this->assertSame( $canonicalOutput, $preparedEdit->output );
		$this->assertSame( $updater->getRawContent( 'main' ), $preparedEdit->pstContent );
		$this->assertSame( $updater->getCanonicalParserOptions(), $preparedEdit->popts );
		$this->assertSame( $rev->getId(), $preparedEdit->revid );
	}

	public function testGetSecondaryDataUpdatesAfterPrepareContent() {
		$user = $this->getTestUser()->getUser();
		$page = $this->getPage( __METHOD__ );
		$this->createRevision( $page, __METHOD__ );

		$mainContent1 = new WikitextContent( 'first' );

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent1 );
		$updater = $this->getDerivedPageDataUpdater( $page );
		$updater->prepareContent( $user, $update, false );

		$dataUpdates = $updater->getSecondaryDataUpdates();

		$this->assertNotEmpty( $dataUpdates );

		$linksUpdates = array_filter( $dataUpdates, function ( $du ) {
			return $du instanceof LinksUpdate;
		} );
		$this->assertCount( 1, $linksUpdates );
	}

	/**
	 * @param string $name
	 *
	 * @return ContentHandler
	 */
	private function defineMockContentModelForUpdateTesting( $name ) {
		/** @var ContentHandler|MockObject $handler */
		$handler = $this->getMockBuilder( TextContentHandler::class )
			->setConstructorArgs( [ $name ] )
			->setMethods(
				[ 'getSecondaryDataUpdates', 'getDeletionUpdates', 'unserializeContent' ]
			)
			->getMock();

		$dataUpdate = new MWCallableUpdate( 'time' );
		$dataUpdate->_name = "$name data update";

		$deletionUpdate = new MWCallableUpdate( 'time' );
		$deletionUpdate->_name = "$name deletion update";

		$handler->method( 'getSecondaryDataUpdates' )->willReturn( [ $dataUpdate ] );
		$handler->method( 'getDeletionUpdates' )->willReturn( [ $deletionUpdate ] );
		$handler->method( 'unserializeContent' )->willReturnCallback(
			function ( $text ) use ( $handler ) {
				return $this->createMockContent( $handler, $text );
			}
		);

		$this->mergeMwGlobalArrayValue(
			'wgContentHandlers', [
				$name => function () use ( $handler ){
					return $handler;
				}
			]
		);

		return $handler;
	}

	/**
	 * @param ContentHandler $handler
	 * @param string $text
	 *
	 * @return Content
	 */
	private function createMockContent( ContentHandler $handler, $text ) {
		/** @var Content|MockObject $content */
		$content = $this->getMockBuilder( TextContent::class )
			->setConstructorArgs( [ $text ] )
			->setMethods( [ 'getModel', 'getContentHandler' ] )
			->getMock();

		$content->method( 'getModel' )->willReturn( $handler->getModelID() );
		$content->method( 'getContentHandler' )->willReturn( $handler );

		return $content;
	}

	public function testGetSecondaryDataUpdatesWithSlotRemoval() {
		global $wgMultiContentRevisionSchemaMigrationStage;

		if ( ! ( $wgMultiContentRevisionSchemaMigrationStage & SCHEMA_COMPAT_READ_NEW ) ) {
			$this->markTestSkipped( 'Slot removal cannot happen with MCR being enabled' );
		}

		$m1 = $this->defineMockContentModelForUpdateTesting( 'M1' );
		$a1 = $this->defineMockContentModelForUpdateTesting( 'A1' );
		$m2 = $this->defineMockContentModelForUpdateTesting( 'M2' );

		$mainContent1 = $this->createMockContent( $m1, 'main 1' );
		$auxContent1 = $this->createMockContent( $a1, 'aux 1' );
		$mainContent2 = $this->createMockContent( $m2, 'main 2' );

		$user = $this->getTestUser()->getUser();
		$page = $this->getPage( __METHOD__ );
		$this->createRevision(
			$page,
			__METHOD__,
			[ 'main' => $mainContent1, 'aux' => $auxContent1 ]
		);

		$update = new RevisionSlotsUpdate();
		$update->modifyContent( 'main', $mainContent2 );
		$update->removeSlot( 'aux' );

		$page = $this->getPage( __METHOD__ );
		$updater = $this->getDerivedPageDataUpdater( $page );
		$updater->prepareContent( $user, $update, false );

		$dataUpdates = $updater->getSecondaryDataUpdates();

		$this->assertNotEmpty( $dataUpdates );

		$updateNames = array_map( function ( $du ) {
			return isset( $du->_name ) ? $du->_name : get_class( $du );
		}, $dataUpdates );

		$this->assertContains( LinksUpdate::class, $updateNames );
		$this->assertContains( 'A1 deletion update', $updateNames );
		$this->assertContains( 'M2 data update', $updateNames );
		$this->assertNotContains( 'M1 data update', $updateNames );
	}

	/**
	 * Creates a dummy revision object without touching the database.
	 *
	 * @param Title $title
	 * @param RevisionSlotsUpdate $update
	 * @param User $user
	 * @param string $comment
	 * @param int $id
	 * @param int $parentId
	 *
	 * @return MutableRevisionRecord
	 */
	private function makeRevision(
		Title $title,
		RevisionSlotsUpdate $update,
		User $user,
		$comment,
		$id,
		$parentId = 0
	) {
		$rev = new MutableRevisionRecord( $title );

		$rev->applyUpdate( $update );
		$rev->setUser( $user );
		$rev->setComment( CommentStoreComment::newUnsavedComment( $comment ) );
		$rev->setId( $id );
		$rev->setPageId( $title->getArticleID() );
		$rev->setParentId( $parentId );

		return $rev;
	}

	/**
	 * @param int $id
	 * @return Title
	 */
	private function getMockTitle( $id = 23 ) {
		$mock = $this->getMockBuilder( Title::class )
			->disableOriginalConstructor()
			->getMock();
		$mock->expects( $this->any() )
			->method( 'getDBkey' )
			->will( $this->returnValue( __CLASS__ ) );
		$mock->expects( $this->any() )
			->method( 'getArticleID' )
			->will( $this->returnValue( $id ) );

		return $mock;
	}

	public function provideIsReusableFor() {
		$title = $this->getMockTitle();

		$user1 = User::newFromName( 'Alice' );
		$user2 = User::newFromName( 'Bob' );

		$content1 = new WikitextContent( 'one' );
		$content2 = new WikitextContent( 'two' );

		$update1 = new RevisionSlotsUpdate();
		$update1->modifyContent( 'main', $content1 );

		$update1b = new RevisionSlotsUpdate();
		$update1b->modifyContent( 'xyz', $content1 );

		$update2 = new RevisionSlotsUpdate();
		$update2->modifyContent( 'main', $content2 );

		$rev1 = $this->makeRevision( $title, $update1, $user1, 'rev1', 11 );
		$rev1b = $this->makeRevision( $title, $update1b, $user1, 'rev1', 11 );

		$rev2 = $this->makeRevision( $title, $update2, $user1, 'rev2', 12 );
		$rev2x = $this->makeRevision( $title, $update2, $user2, 'rev2', 12 );
		$rev2y = $this->makeRevision( $title, $update2, $user1, 'rev2', 122 );

		yield 'any' => [
			'$prepUser' => null,
			'$prepRevision' => null,
			'$prepUpdate' => null,
			'$forUser' => null,
			'$forRevision' => null,
			'$forUpdate' => null,
			'$forParent' => null,
			'$isReusable' => true,
		];
		yield 'for any' => [
			'$prepUser' => $user1,
			'$prepRevision' => $rev1,
			'$prepUpdate' => $update1,
			'$forUser' => null,
			'$forRevision' => null,
			'$forUpdate' => null,
			'$forParent' => null,
			'$isReusable' => true,
		];
		yield 'unprepared' => [
			'$prepUser' => null,
			'$prepRevision' => null,
			'$prepUpdate' => null,
			'$forUser' => $user1,
			'$forRevision' => $rev1,
			'$forUpdate' => $update1,
			'$forParent' => 0,
			'$isReusable' => true,
		];
		yield 'match prepareContent' => [
			'$prepUser' => $user1,
			'$prepRevision' => null,
			'$prepUpdate' => $update1,
			'$forUser' => $user1,
			'$forRevision' => null,
			'$forUpdate' => $update1,
			'$forParent' => 0,
			'$isReusable' => true,
		];
		yield 'match prepareUpdate' => [
			'$prepUser' => null,
			'$prepRevision' => $rev1,
			'$prepUpdate' => null,
			'$forUser' => $user1,
			'$forRevision' => $rev1,
			'$forUpdate' => null,
			'$forParent' => 0,
			'$isReusable' => true,
		];
		yield 'match all' => [
			'$prepUser' => $user1,
			'$prepRevision' => $rev1,
			'$prepUpdate' => $update1,
			'$forUser' => $user1,
			'$forRevision' => $rev1,
			'$forUpdate' => $update1,
			'$forParent' => 0,
			'$isReusable' => true,
		];
		yield 'mismatch prepareContent update' => [
			'$prepUser' => $user1,
			'$prepRevision' => null,
			'$prepUpdate' => $update1,
			'$forUser' => $user1,
			'$forRevision' => null,
			'$forUpdate' => $update1b,
			'$forParent' => 0,
			'$isReusable' => false,
		];
		yield 'mismatch prepareContent user' => [
			'$prepUser' => $user1,
			'$prepRevision' => null,
			'$prepUpdate' => $update1,
			'$forUser' => $user2,
			'$forRevision' => null,
			'$forUpdate' => $update1,
			'$forParent' => 0,
			'$isReusable' => false,
		];
		yield 'mismatch prepareContent parent' => [
			'$prepUser' => $user1,
			'$prepRevision' => null,
			'$prepUpdate' => $update1,
			'$forUser' => $user1,
			'$forRevision' => null,
			'$forUpdate' => $update1,
			'$forParent' => 7,
			'$isReusable' => false,
		];
		yield 'mismatch prepareUpdate revision update' => [
			'$prepUser' => null,
			'$prepRevision' => $rev1,
			'$prepUpdate' => null,
			'$forUser' => null,
			'$forRevision' => $rev1b,
			'$forUpdate' => null,
			'$forParent' => 0,
			'$isReusable' => false,
		];
		yield 'mismatch prepareUpdate revision user' => [
			'$prepUser' => null,
			'$prepRevision' => $rev2,
			'$prepUpdate' => null,
			'$forUser' => null,
			'$forRevision' => $rev2x,
			'$forUpdate' => null,
			'$forParent' => 0,
			'$isReusable' => false,
		];
		yield 'mismatch prepareUpdate revision id' => [
			'$prepUser' => null,
			'$prepRevision' => $rev2,
			'$prepUpdate' => null,
			'$forUser' => null,
			'$forRevision' => $rev2y,
			'$forUpdate' => null,
			'$forParent' => 0,
			'$isReusable' => false,
		];
	}

	/**
	 * @dataProvider provideIsReusableFor
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::isReusableFor()
	 *
	 * @param User|null $prepUser
	 * @param RevisionRecord|null $prepRevision
	 * @param RevisionSlotsUpdate|null $prepUpdate
	 * @param User|null $forUser
	 * @param RevisionRecord|null $forRevision
	 * @param RevisionSlotsUpdate|null $forUpdate
	 * @param int|null $forParent
	 * @param bool $isReusable
	 */
	public function testIsReusableFor(
		User $prepUser = null,
		RevisionRecord $prepRevision = null,
		RevisionSlotsUpdate $prepUpdate = null,
		User $forUser = null,
		RevisionRecord $forRevision = null,
		RevisionSlotsUpdate $forUpdate = null,
		$forParent = null,
		$isReusable = null
	) {
		$updater = $this->getDerivedPageDataUpdater( __METHOD__ );

		if ( $prepUpdate ) {
			$updater->prepareContent( $prepUser, $prepUpdate, false );
		}

		if ( $prepRevision ) {
			$updater->prepareUpdate( $prepRevision );
		}

		$this->assertSame(
			$isReusable,
			$updater->isReusableFor( $forUser, $forRevision, $forUpdate, $forParent )
		);
	}

	/**
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::doUpdates()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::doSecondaryDataUpdates()
	 * @covers \MediaWiki\Storage\DerivedPageDataUpdater::doParserCacheUpdate()
	 */
	public function testDoUpdates() {
		$page = $this->getPage( __METHOD__ );

		$content = [ 'main' => new WikitextContent( 'first [[main]]' ) ];

		if ( $this->hasMultiSlotSupport() ) {
			$content['aux'] = new WikitextContent( 'Aux [[Nix]]' );
		}

		$rev = $this->createRevision( $page, 'first', $content );
		$pageId = $page->getId();

		$oldStats = $this->db->selectRow( 'site_stats', '*', '1=1' );
		$this->db->delete( 'pagelinks', '*' );

		$pcache = MediaWikiServices::getInstance()->getParserCache();
		$pcache->deleteOptionsKey( $page );

		$updater = $this->getDerivedPageDataUpdater( $page, $rev );
		$updater->setArticleCountMethod( 'link' );

		$options = []; // TODO: test *all* the options...
		$updater->prepareUpdate( $rev, $options );

		$updater->doUpdates();

		// links table update
		$pageLinks = $this->db->select(
			'pagelinks',
			'*',
			[ 'pl_from' => $pageId ],
			__METHOD__,
			[ 'ORDER BY' => 'pl_namespace, pl_title' ]
		);

		$pageLinksRow = $pageLinks->fetchObject();
		$this->assertInternalType( 'object', $pageLinksRow );
		$this->assertSame( 'Main', $pageLinksRow->pl_title );

		if ( $this->hasMultiSlotSupport() ) {
			$pageLinksRow = $pageLinks->fetchObject();
			$this->assertInternalType( 'object', $pageLinksRow );
			$this->assertSame( 'Nix', $pageLinksRow->pl_title );
		}

		// parser cache update
		$cached = $pcache->get( $page, $updater->getCanonicalParserOptions() );
		$this->assertInternalType( 'object', $cached );
		$this->assertSame( $updater->getCanonicalParserOutput(), $cached );

		// site stats
		$stats = $this->db->selectRow( 'site_stats', '*', '1=1' );
		$this->assertSame( $oldStats->ss_total_pages + 1, (int)$stats->ss_total_pages );
		$this->assertSame( $oldStats->ss_total_edits + 1, (int)$stats->ss_total_edits );
		$this->assertSame( $oldStats->ss_good_articles + 1, (int)$stats->ss_good_articles );

		// TODO: MCR: test data updates for additional slots!
		// TODO: test update for edit without page creation
		// TODO: test message cache purge
		// TODO: test module cache purge
		// TODO: test CDN purge
		// TODO: test newtalk update
		// TODO: test search update
		// TODO: test site stats good_articles while turning the page into (or back from) a redir.
		// TODO: test category membership update (with setRcWatchCategoryMembership())
	}

	private function hasMultiSlotSupport() {
		global $wgMultiContentRevisionSchemaMigrationStage;

		return ( $wgMultiContentRevisionSchemaMigrationStage & SCHEMA_COMPAT_WRITE_NEW )
			&& ( $wgMultiContentRevisionSchemaMigrationStage & SCHEMA_COMPAT_READ_NEW );
	}

}