diff --git a/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
index dc93d42..410cc4f 100644
--- a/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -331,7 +331,7 @@ function simpletest_phpunit_run_command(array $unescaped_test_classnames, $phpun
   // this variable.
   if ($base_url) {
     putenv('SIMPLETEST_BASE_URL=' . $base_url);
-    putenv('BROWSERTEST_OUTPUT_DIRECTORY=' . Drupal::service('file_system')->realpath('public://simpletest'));
+    putenv('BROWSERTEST_OUTPUT_DIRECTORY=' . \Drupal::service('file_system')->realpath('public://simpletest'));
   }
   $phpunit_bin = simpletest_phpunit_command();
 
diff --git a/core/modules/simpletest/src/Tests/UiPhpUnitOutputTest.php b/core/modules/simpletest/src/Tests/UiPhpUnitOutputTest.php
new file mode 100644
index 0000000..8f8b6c5
--- /dev/null
+++ b/core/modules/simpletest/src/Tests/UiPhpUnitOutputTest.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Drupal\simpletest\Tests;
+
+use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\simpletest\Functional\SimpletestPhpunitBrowserTest;
+
+/**
+ * Test PHPUnit output for the Simpletest UI.
+ *
+ * @group simpletest
+ */
+class UiPhpUnitOutputTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var string[]
+   */
+  public static $modules = ['simpletest'];
+
+  /**
+   * Tests that PHPUnit output in the Simpletest UI looks good.
+   */
+  public function testOutput() {
+    require_once __DIR__ . '/../../tests/fixtures/simpletest_phpunit_browsertest.php';
+    $phpunit_junit_file = \Drupal::service('file_system')->realpath('public://phpunit_junit.xml');
+    // Prepare the default browser test output directory in the child site.
+    \Drupal::service('file_system')->mkdir('public://simpletest');
+    $status = 0;
+    $output = [];
+    simpletest_phpunit_run_command([SimpletestPhpunitBrowserTest::class], $phpunit_junit_file, $status, $output);
+
+    $this->verbose(print_r($output, TRUE));
+
+    // Check that there are <br> tags for the HTML output by
+    // SimpletestUiPrinter.
+    $this->assertEqual($output[9], 'HTML output was generated<br />');
+    // Check that URLs are printed as HTML links.
+    $this->assertIdentical(strpos($output[10], '<a href="http'), 0);
+  }
+
+}
diff --git a/core/modules/simpletest/tests/fixtures/simpletest_phpunit_browsertest.php b/core/modules/simpletest/tests/fixtures/simpletest_phpunit_browsertest.php
new file mode 100644
index 0000000..059d818
--- /dev/null
+++ b/core/modules/simpletest/tests/fixtures/simpletest_phpunit_browsertest.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\Tests\simpletest\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * A PHPUnit-based browser test that will be run from Simpletest.
+ *
+ * To avoid accidentally running it is not in a normal PSR-4 directory.
+ *
+ * @group simpletest
+ */
+class SimpletestPhpunitBrowserTest extends BrowserTestBase {
+
+  /**
+   * Dummy test that logs the visited front page for HTML output.
+   */
+  public function testOutput() {
+    $this->drupalGet('<front>');
+  }
+
+}