Add basic tests for ULS' ResourceLoader modules

This is a starting point to increase the test coverage in this code
base.

Change-Id: I215713e928e9b55615afd17ccf7a7082ef559e01

tests/phpunit/ResourceLoaderULSJsonMessageModuleTest.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace UniversalLanguageSelector\Tests;
+
+use ResourceLoaderULSJsonMessageModule;
+
+/**
+ * @covers \ResourceLoaderULSJsonMessageModule
+ *
+ * @license GPL-2.0-or-later
+ * @author Thiemo Kreuz
+ */
+class ResourceLoaderULSJsonMessageModuleTest extends \PHPUnit\Framework\TestCase {
+	use \PHPUnit4And6Compat;
+
+	public function testAllReturnValues() {
+		$instance = new ResourceLoaderULSJsonMessageModule();
+
+		$context = $this->createMock( \ResourceLoaderContext::class );
+		$context->method( 'getLanguage' )
+			->willReturn( 'en' );
+
+		$this->assertContainsOnly( 'string', $instance->getDependencies(), 'dependencies' );
+		$this->assertContainsOnly( 'string', $instance->getTargets(), 'targets' );
+
+		$summary = $instance->getDefinitionSummary( $context );
+		$lastElement = end( $summary );
+		$this->assertArrayHasKey( 'fileHashes', $lastElement );
+		$this->assertContainsOnly( 'string', $lastElement['fileHashes'] );
+
+		$script = $instance->getScript( $context );
+		$this->assertStringStartsWith( 'mw.uls.loadLocalization("en",{"', $script );
+	}
+
+}