Introduce ReferenceMessageLocalizer

Encapsulate the language interfaces, this will be used to replace
global wfMessage calls in future patches.

Change-Id: I7857f3e5154626e0b29977610b81103d91615f65

src/ReferenceMessageLocalizer.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Cite;
+
+use Language;
+use Message;
+use MessageLocalizer;
+use MessageSpecifier;
+
+class ReferenceMessageLocalizer implements MessageLocalizer {
+
+	/**
+	 * @var Language
+	 */
+	private $language;
+
+	/**
+	 * @param Language $language
+	 */
+	public function __construct( Language $language ) {
+		$this->language = $language;
+	}
+
+	/**
+	 * @return Language
+	 */
+	public function getLanguage(): Language {
+		return $this->language;
+	}
+
+	/**
+	 * This is the method for getting translated interface messages.
+	 *
+	 * @see https://www.mediawiki.org/wiki/Manual:Messages_API
+	 * @see Message::__construct
+	 *
+	 * @param string|string[]|MessageSpecifier $key Message key, or array of keys,
+	 *   or a MessageSpecifier.
+	 * @param mixed ...$params Normal message parameters
+	 * @return Message
+	 */
+	public function msg( $key, ...$params ): Message {
+		return wfMessage( $key, ...$params )->inLanguage( $this->language );
+	}
+
+}

tests/phpunit/ReferenceMessageLocalizerTest.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Cite;
+
+use LanguageQqx;
+use MediaWikiIntegrationTestCase;
+
+/**
+ * @coversDefaultClass \Cite\ReferenceMessageLocalizer
+ */
+class ReferenceMessageLocalizerTest extends MediaWikiIntegrationTestCase {
+	/**
+	 * @covers ::msg
+	 */
+	public function testMsg() {
+		$localizer = new ReferenceMessageLocalizer( new LanguageQqx() );
+		$this->assertSame(
+			'(cite_reference_link_prefix)',
+			$localizer->msg( 'cite_reference_link_prefix' )->plain() );
+	}
+}