TemplateParser: Test server-local cache interaction

Add integration tests covering how TemplateParser::getTemplate interacts
with the server-local cache.

Bug: T113095
Change-Id: Ie0da8a157796bfe8ab4d758f38a4c6a2d5dc90ce

tests/phpunit/integration/includes/TemplateParserTest.php

@@ -0,0 +1,132 @@
+<?php
+
+use LightnCandy\LightnCandy;
+use Wikimedia\TestingAccessWrapper;
+
+/**
+ * @group Templates
+ * @coversDefaultClass TemplateParser
+ */
+class TemplateParserTest extends MediaWikiIntegrationTestCase {
+
+	private const TEMPLATE_NAME = 'foobar';
+
+	private $secretKey;
+	private $cache;
+	private $templateDir;
+	private $templateParser;
+
+	private function makeKey() : string {
+		return $this->cache->makeKey(
+			'lightncandy-compiled',
+
+			// See TemplateParser::$cacheVersion
+			'2.1.0',
+
+			// See TemplateParser::__construct and TemplateParser::$compileFlags
+			LightnCandy::FLAG_ERROR_EXCEPTION | LightnCandy::FLAG_MUSTACHELOOKUP,
+
+			self::TEMPLATE_NAME
+		);
+	}
+
+	private function getTemplate() {
+		//
+		// NOTE: Deliberately destroy the per-instance cache every time we render a template in
+		// order to test interactions with the server-local cache.
+		$templateParser = TestingAccessWrapper::newFromObject(
+			new TemplateParser( $this->templateDir )
+		);
+
+		return $templateParser->getTemplate( self::TEMPLATE_NAME );
+	}
+
+	// Tests
+	// =====
+
+	protected function setUp() : void {
+		parent::setUp();
+
+		// Data
+		$this->secretKey = 'foo';
+		$this->setMwGlobals( [
+			'wgSecretKey' => $this->secretKey,
+		] );
+		$this->templateDir = __DIR__ . '/../../data/templates';
+
+		// Stubs
+		$this->cache = ObjectCache::getLocalServerInstance( CACHE_ANYTHING );
+	}
+
+	/**
+	 * @covers ::getTemplate
+	 */
+	public function testGetTemplateCachesCompilationResult() {
+		$this->getTemplate();
+
+		$value = $this->cache->get( $this->makeKey() );
+
+		$this->assertIsArray( $value );
+		$this->assertArrayHasKey( 'phpCode', $value );
+		$this->assertArrayHasKey( 'files', $value );
+		$this->assertArrayHasKey( 'filesHash', $value );
+
+		// ---
+
+		$this->assertEquals(
+			hash_hmac( 'sha256', $value['phpCode'], $this->secretKey ),
+			$value['integrityHash'],
+			'::getTemplate adds an integrity hash to the compiled template before caching it.'
+		);
+	}
+
+	/**
+	 * @covers ::getTemplate
+	 */
+	public function testGetTemplateInvalidatesCacheWhenFilesHashIsInvalid() {
+		$key = $this->makeKey();
+		$this->cache->set( $key, [
+			'phpCode' => 'foo',
+			'files' => [ 'bar' ],
+			'filesHash' => 'baz',
+		] );
+
+		$this->getTemplate();
+
+		$expectedFiles = [ $this->templateDir . '/' . self::TEMPLATE_NAME . '.mustache' ];
+		$expectedFilesHash = FileContentsHasher::getFileContentsHash( $expectedFiles );
+
+		$value = $this->cache->get( $this->makeKey() );
+
+		$this->assertNotEquals( 'foo', $value['phpCode'] );
+		$this->assertEquals( $expectedFiles, $value['files'] );
+		$this->assertEquals(
+			$expectedFilesHash,
+			$value['filesHash'],
+			'The cached compiled template was invalidated.'
+		);
+	}
+
+	/**
+	 * @covers ::getTemplate
+	 */
+	public function testGetTemplateInvalidatesCacheWhenIntegrityHashIsInvalid() {
+		$this->getTemplate();
+
+		$key = $this->makeKey();
+		$value = $this->cache->get( $key );
+
+		$value['integrityHash'] = 'foo';
+		$this->cache->set( $key, $value );
+
+		$this->getTemplate();
+
+		$newValue = $this->cache->get( $key );
+
+		$this->assertNotEquals(
+			$newValue['integrityHash'],
+			$value['integrityHash'],
+			'The cached compiled template was invalidated.'
+		);
+	}
+}