Issue #2878248 by Mile23, dawehner: DrupalStandardsListener improper handling...

Issue #2878248 by Mile23, dawehner: DrupalStandardsListener improper handling of @trigger_error() deprecation

core/modules/system/tests/modules/deprecation_test/deprecation_test.info.yml

+name: 'Deprecation test'
+type: module
+description: 'Support module for testing deprecation behaviors.'
+package: Testing
+version: VERSION
+core: 8.x

core/modules/system/tests/modules/deprecation_test/src/Deprecation/FixtureDeprecatedClass.php

+<?php
+
+namespace Drupal\deprecation_test\Deprecation;
+
+@trigger_error(__NAMESPACE__ . '\FixtureDeprecatedClass is deprecated.', E_USER_DEPRECATED);
+
+/**
+ * Fixture class for use by DrupalStandardsListenerDeprecationTest.
+ *
+ * This class is arbitrarily deprecated in order to test the deprecation error
+ * handling properties of DrupalStandardsListener.
+ *
+ * @see \Drupal\Tests\Core\Listeners\DrupalStandardsListenerDeprecationTest
+ * @see \Drupal\Tests\Listeners\DrupalStandardsListener::endTest()
+ */
+class FixtureDeprecatedClass {
+
+  /**
+   * Returns a known value.
+   *
+   * @return string
+   *   A known return value.
+   */
+  public function testFunction() {
+    return 'test';
+  }
+
+}

core/tests/Drupal/Tests/Core/Listeners/DrupalStandardsListenerDeprecationTest.php

+<?php
+
+namespace Drupal\Tests\Core\Listeners;
+
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * Test deprecation error handling by DrupalStandardsListener.
+ *
+ * DrupalStandardsListener has a dependency on composer/composer, so we can't
+ * test it directly. However, we can create a test which is annotated as
+ * covering a deprecated class. This way we can know whether the standards
+ * listener process handles deprecation errors properly.
+ *
+ * Note that this test is annotated as covering
+ * \Drupal\deprecation_test\Deprecation\FixtureDeprecatedClass::testFunction(),
+ * but the reason the test exists is to cover
+ * \Drupal\Tests\Listeners\DrupalStandardsListener::endTest(). We never
+ * actually instantiate
+ * \Drupal\deprecation_test\Deprecation\FixtureDeprecatedClass because that
+ * would trigger another deprecation error.
+ *
+ * @group Listeners
+ *
+ * @coversDefaultClass \Drupal\deprecation_test\Deprecation\FixtureDeprecatedClass
+ */
+class DrupalStandardsListenerDeprecationTest extends UnitTestCase {
+
+  /**
+   * Exercise DrupalStandardsListener's coverage validation.
+   *
+   * @covers ::testFunction
+   */
+  public function testDeprecation() {
+    // Meaningless assertion so this test is not risky.
+    $this->assertTrue(TRUE);
+  }
+
+}

core/tests/Drupal/Tests/Listeners/DrupalStandardsListener.php

@@ -142,6 +142,16 @@ public function checkValidCoversForTest(TestCase $test) {
 
   /**
    * {@inheritdoc}
+   *
+   * We must mark this method as belonging to the special legacy group because
+   * it might trigger an E_USER_DEPRECATED error during coverage annotation
+   * validation. The legacy group allows symfony/phpunit-bridge to keep the
+   * deprecation notice as a warning instead of an error, which would fail the
+   * test.
+   *
+   * @group legacy
+   *
+   * @see http://symfony.com/doc/current/components/phpunit_bridge.html#mark-tests-as-legacy
    */
   public function endTest(\PHPUnit_Framework_Test $test, $time) {
     // \PHPUnit_Framework_Test does not have any useful methods of its own for