First working test.

tests/phpunit/TestCase.php

@@ -0,0 +1,19 @@
+<?php
+namespace LinkTitles;
+
+abstract class TestCase extends \MediaWikiTestCase {
+  protected function setUp() {
+    parent::setUp();
+    $this->insertPage( 'link target', 'This page serves as a link target' );
+    Extension::invalidateCache();
+  }
+
+  protected function tearDown() {
+    parent::tearDown();
+  }
+
+  protected function getPageText( \WikiPage $page ) {
+    $content = $page->getContent();
+    return $page->getContentHandler()->serializeContent( $content );
+  }
+}