diff --git a/core/modules/toolbar/tests/src/FunctionalJavascript/ToolbarIntegrationTest.php b/core/modules/toolbar/tests/src/FunctionalJavascript/ToolbarIntegrationTest.php
index c22443c..326effb 100644
--- a/core/modules/toolbar/tests/src/FunctionalJavascript/ToolbarIntegrationTest.php
+++ b/core/modules/toolbar/tests/src/FunctionalJavascript/ToolbarIntegrationTest.php
@@ -30,23 +30,23 @@ public function testToolbarToggling() {
     $this->drupalGet('<front>');
 
     // Test that it is possible to toggle the toolbar tray.
-    $this->assertTrue($this->getSession()->getDriver()->isVisible('.//a[@id="toolbar-link-system-admin_content"]'), 'Toolbar tray is open by default.');
-    $this->getSession()->getDriver()->click('.//a[@id="toolbar-item-administration"]');
-    $this->assertFalse($this->getSession()->getDriver()->isVisible('//a[@id="toolbar-link-system-admin_content"]'), 'Toolbar tray is closed after clicking the "Manage" button.');
-    $this->getSession()->getDriver()->click('.//a[@id="toolbar-item-administration"]');
-    $this->assertTrue($this->getSession()->getDriver()->isVisible('//a[@id="toolbar-link-system-admin_content"]'), 'Toolbar tray is visible again after clicking the "Manage" button a second time.');
+    $this->assertElementVisible('#toolbar-link-system-admin_content', 'Toolbar tray is open by default.');
+    $this->click('a#toolbar-item-administration');
+    $this->assertElementNotVisible('#toolbar-link-system-admin_content', 'Toolbar tray is closed after clicking the "Manage" button.');
+    $this->click('a#toolbar-item-administration');
+    $this->assertElementVisible('#toolbar-link-system-admin_content', 'Toolbar tray is visible again after clicking the "Manage" button a second time.');
 
     // Test toggling the toolbar tray between horizontal and vertical.
-    $this->assertTrue($this->getSession()->getDriver()->isVisible('.//div[@id="toolbar-item-administration-tray" and contains(concat(" ", @class, " "), " toolbar-tray-horizontal ")]'), 'Toolbar tray is horizontally oriented by default.');
-    $this->assertEmpty($this->getSession()->getDriver()->find('.//div[@id="toolbar-item-administration-tray" and contains(concat(" ", @class, " "), " toolbar-tray-vertical ")]'), 'Toolbar tray not vertically oriented by default.');
+    $this->assertElementVisible('#toolbar-item-administration-tray.toolbar-tray-horizontal', 'Toolbar tray is horizontally oriented by default.');
+    $this->assertElementNotPresent('#toolbar-item-administration-tray.toolbar-tray-vertical', 'Toolbar tray is not vertically oriented by default.');
 
-    $this->getSession()->getDriver()->click('.//div[@id="toolbar-item-administration-tray"]//button[contains(concat(" ", @class, " "), " toolbar-icon-toggle-vertical ")]');
-    $this->assertTrue($this->getSession()->getDriver()->wait(1000, 'jQuery("#toolbar-item-administration-tray").hasClass("toolbar-tray-vertical")'));
-    $this->assertTrue($this->getSession()->getDriver()->isVisible('.//div[@id="toolbar-item-administration-tray" and contains(concat(" ", @class, " "), " toolbar-tray-vertical ")]'), 'After toggling the orientation the toolbar tray is now displayed vertically.');
+    $this->click('#toolbar-item-administration-tray button.toolbar-icon-toggle-vertical');
+    $this->assertTrue($this->wait(1000, 'jQuery("#toolbar-item-administration-tray").hasClass("toolbar-tray-vertical")'));
+    $this->assertElementVisible('div#toolbar-item-administration-tray.toolbar-tray-vertical', 'After toggling the orientation the toolbar tray is now displayed vertically.');
 
-    $this->getSession()->getDriver()->click('.//div[@id="toolbar-item-administration-tray"]//button[contains(concat(" ", @class, " "), " toolbar-icon-toggle-horizontal ")]');
-    $this->assertTrue($this->getSession()->getDriver()->wait(1000, 'jQuery("#toolbar-item-administration-tray").hasClass("toolbar-tray-horizontal")'));
-    $this->assertTrue($this->getSession()->getDriver()->isVisible('.//div[@id="toolbar-item-administration-tray" and contains(concat(" ", @class, " "), " toolbar-tray-horizontal ")]'), 'After toggling the orientation a second time the toolbar tray is displayed horizontally again.');
+    $this->click('#toolbar-item-administration-tray button.toolbar-icon-toggle-horizontal');
+    $this->assertTrue($this->wait(1000, 'jQuery("#toolbar-item-administration-tray").hasClass("toolbar-tray-horizontal")'));
+    $this->assertElementVisible('div#toolbar-item-administration-tray.toolbar-tray-horizontal', 'After toggling the orientation a second time the toolbar tray is displayed horizontally again.');
   }
 
 }
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php b/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
index 00daa43..043ba84 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/JavascriptTestBase.php
@@ -33,4 +33,90 @@ protected function initMink() {
     parent::initMink();
   }
 
+  /**
+   * Asserts that the element with the given CSS selector is visible.
+   *
+   * @param string $css_selector
+   *   The CSS selector identifying the element to check.
+   * @param string $message
+   *   Optional message to show alongside the assertion.
+   */
+  protected function assertElementVisible($css_selector, $message = '') {
+    $this->assertTrue($this->getSession()->getDriver()->isVisible($this->selectorToXpath($css_selector)), $message);
+  }
+
+  /**
+   * Asserts that the element with the given CSS selector is not visible.
+   *
+   * @param string $css_selector
+   *   The CSS selector identifying the element to check.
+   * @param string $message
+   *   Optional message to show alongside the assertion.
+   */
+  protected function assertElementNotVisible($css_selector, $message = '') {
+    $this->assertFalse($this->getSession()->getDriver()->isVisible($this->selectorToXpath($css_selector)), $message);
+  }
+
+  /**
+   * Asserts that the element with the given CSS selector is present.
+   *
+   * @param string $css_selector
+   *   The CSS selector identifying the element to check.
+   * @param string $message
+   *   Optional message to show alongside the assertion.
+   */
+  protected function assertElementPresent($css_selector, $message = '') {
+    $this->assertNotEmpty($this->getSession()->getDriver()->find($this->selectorToXpath($css_selector)), $message);
+  }
+
+  /**
+   * Asserts that the element with the given CSS selector is not present.
+   *
+   * @param string $css_selector
+   *   The CSS selector identifying the element to check.
+   * @param string $message
+   *   Optional message to show alongside the assertion.
+   */
+  protected function assertElementNotPresent($css_selector, $message = '') {
+    $this->assertEmpty($this->getSession()->getDriver()->find($this->selectorToXpath($css_selector)), $message);
+  }
+
+  /**
+   * Clicks the element with the given CSS selector.
+   *
+   * @param string $css_selector
+   *   The CSS selector identifying the element to click.
+   */
+  protected function click($css_selector) {
+    $this->getSession()->getDriver()->click($this->selectorToXpath($css_selector));
+  }
+
+  /**
+   * Waits for the given time or until the given JS condition becomes TRUE.
+   *
+   * @param int $timeout
+   *   Timeout in milliseconds.
+   * @param string|bool $condition
+   *   JS condition, or FALSE to wait for the full duration of the timeout.
+   *
+   * @return bool
+   *   The result of the JS condition.
+   */
+  protected function wait($timeout, $condition = FALSE) {
+    return $this->getSession()->getDriver()->wait($timeout, $condition);
+  }
+
+  /**
+   * Converts the given CSS selector to an XPath expression.
+   *
+   * @param string $css_selector
+   *   The CSS selector to convert.
+   *
+   * @return string
+   *   The converted XPath expression.
+   */
+  protected function selectorToXpath($css_selector) {
+    return $this->getSession()->getSelectorsHandler()->selectorToXpath('css', $css_selector);
+  }
+
 }