Improve ExtensionRegistry test coverage

Change-Id: I7f7445952f057995a3e3215145803affa5aceede

includes/registration/ExtensionRegistry.php

@@ -82,6 +82,7 @@ class ExtensionRegistry {
 	private static $instance;
 
 	/**
+	 * @codeCoverageIgnore
 	 * @return ExtensionRegistry
 	 */
 	public static function getInstance() {
@@ -105,9 +106,11 @@ class ExtensionRegistry {
 			} else {
 				throw new Exception( "$path does not exist!" );
 			}
+			// @codeCoverageIgnoreStart
 			if ( !$mtime ) {
 				$err = error_get_last();
 				throw new Exception( "Couldn't stat $path: {$err['message']}" );
+				// @codeCoverageIgnoreEnd
 			}
 		}
 		$this->queued[$path] = $mtime;

tests/phpunit/includes/registration/ExtensionRegistryTest.php

@@ -1,9 +1,57 @@
 <?php
 
+/**
+ * @covers ExtensionRegistry
+ */
 class ExtensionRegistryTest extends MediaWikiTestCase {
 
+	private $dataDir;
+
+	public function setUp() {
+		parent::setUp();
+		$this->dataDir = __DIR__ . '/../../data/registration';
+	}
+
+	public function testQueue_invalid() {
+		$registry = new ExtensionRegistry();
+		$path = __DIR__ . '/doesnotexist.json';
+		$this->setExpectedException(
+			Exception::class,
+			"$path does not exist!"
+		);
+		$registry->queue( $path );
+	}
+
+	public function testQueue() {
+		$registry = new ExtensionRegistry();
+		$path = "{$this->dataDir}/good.json";
+		$registry->queue( $path );
+		$this->assertArrayHasKey(
+			$path,
+			$registry->getQueue()
+		);
+		$registry->clearQueue();
+		$this->assertEmpty( $registry->getQueue() );
+	}
+
+	public function testLoadFromQueue_empty() {
+		$registry = new ExtensionRegistry();
+		$registry->loadFromQueue();
+		$this->assertEmpty( $registry->getAllThings() );
+	}
+
+	public function testLoadFromQueue_late() {
+		$registry = new ExtensionRegistry();
+		$registry->finish();
+		$registry->queue( "{$this->dataDir}/good.json" );
+		$this->setExpectedException(
+			MWException::class,
+			"The following paths tried to load late: {$this->dataDir}/good.json"
+		);
+		$registry->loadFromQueue();
+	}
+
 	/**
-	 * @covers ExtensionRegistry::exportExtractedData
 	 * @dataProvider provideExportExtractedDataGlobals
 	 */
 	public function testExportExtractedDataGlobals( $desc, $before, $globals, $expected ) {