diff --git a/core/modules/system/src/Tests/Menu/MenuRouterTest.php b/core/modules/system/src/Tests/Menu/MenuRouterTest.php
index 48c7500..53b2799 100644
--- a/core/modules/system/src/Tests/Menu/MenuRouterTest.php
+++ b/core/modules/system/src/Tests/Menu/MenuRouterTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Menu;
 
+use Drupal\Core\Url;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -62,7 +63,8 @@ public function testMenuIntegration() {
    */
   protected function doTestHookMenuIntegration() {
     // Generate base path with random argument.
-    $base_path = 'foo/' . $this->randomMachineName(8);
+    $machine_name = $this->randomMachineName(8);
+    $base_path = 'foo/' . $machine_name;
     $this->drupalGet($base_path);
     // Confirm correct controller activated.
     $this->assertText('test1');
@@ -70,8 +72,8 @@ protected function doTestHookMenuIntegration() {
     $this->assertLink('Local task A');
     $this->assertLink('Local task B');
     // Confirm correct local task href.
-    $this->assertLinkByHref(_url($base_path));
-    $this->assertLinkByHref(_url($base_path . '/b'));
+    $this->assertLinkByHref(Url::fromRoute('menu_test.router_test1', ['bar' => $machine_name])->toString());
+    $this->assertLinkByHref(Url::fromRoute('menu_test.router_test2', ['bar' => $machine_name])->toString());
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Menu/MenuTranslateTest.php b/core/modules/system/src/Tests/Menu/MenuTranslateTest.php
index ea4b302..e316c95 100644
--- a/core/modules/system/src/Tests/Menu/MenuTranslateTest.php
+++ b/core/modules/system/src/Tests/Menu/MenuTranslateTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Menu;
 
+use Drupal\Core\Url;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -40,7 +41,7 @@ public function testMenuTranslate() {
     $this->assertResponse(403);
     $elements = $this->xpath('//ul[@class=:class]/li/a[@href=:href]', array(
       ':class' => 'tabs primary',
-      ':href' => _url('foo/asdf'),
+      ':href' => Url::fromRoute('menu_test.router_test1', ['bar' => 'asdf'])->toString(),
     ));
     $this->assertTrue(empty($elements), 'No tab linking to foo/asdf found');
     $this->assertNoLinkByHref('foo/asdf/b');
diff --git a/core/modules/system/src/Tests/Theme/FunctionsTest.php b/core/modules/system/src/Tests/Theme/FunctionsTest.php
index f9a4a83..1dd8fd8 100644
--- a/core/modules/system/src/Tests/Theme/FunctionsTest.php
+++ b/core/modules/system/src/Tests/Theme/FunctionsTest.php
@@ -217,7 +217,7 @@ function testLinks() {
     $expected_links .= '<ul id="somelinks">';
     $expected_links .= '<li class="a-link"><a href="' . Url::fromUri('base://a/link')->toString() . '">' . String::checkPlain('A <link>') . '</a></li>';
     $expected_links .= '<li class="plain-text">' . String::checkPlain('Plain "text"') . '</li>';
-    $expected_links .= '<li class="front-page"><a href="' . _url('<front>') . '">' . String::checkPlain('Front page') . '</a></li>';
+    $expected_links .= '<li class="front-page"><a href="' . Url::fromRoute('<front>')->toString() . '">' . String::checkPlain('Front page') . '</a></li>';
     $expected_links .= '<li class="router-test"><a href="' . \Drupal::urlGenerator()->generate('router_test.1') . '">' . String::checkPlain('Test route') . '</a></li>';
     $query = array('key' => 'value');
     $expected_links .= '<li class="query-test"><a href="' . \Drupal::urlGenerator()->generate('router_test.1', $query) . '">' . String::checkPlain('Query test route') . '</a></li>';
@@ -256,7 +256,7 @@ function testLinks() {
     $expected_links .= '<ul id="somelinks">';
     $expected_links .= '<li class="a-link"><a href="' . Url::fromUri('base://a/link')->toString() . '">' . String::checkPlain('A <link>') . '</a></li>';
     $expected_links .= '<li class="plain-text"><span class="a/class">' . String::checkPlain('Plain "text"') . '</span></li>';
-    $expected_links .= '<li class="front-page"><a href="' . _url('<front>') . '">' . String::checkPlain('Front page') . '</a></li>';
+    $expected_links .= '<li class="front-page"><a href="' . Url::fromRoute('<front>')->toString() . '">' . String::checkPlain('Front page') . '</a></li>';
     $expected_links .= '<li class="router-test"><a href="' . \Drupal::urlGenerator()->generate('router_test.1') . '">' . String::checkPlain('Test route') . '</a></li>';
     $query = array('key' => 'value');
     $expected_links .= '<li class="query-test"><a href="' . \Drupal::urlGenerator()->generate('router_test.1', $query) . '">' . String::checkPlain('Query test route') . '</a></li>';
@@ -271,7 +271,7 @@ function testLinks() {
     $expected_links .= '<ul id="somelinks">';
     $expected_links .= '<li class="a-link"><a href="' . Url::fromUri('base://a/link')->toString() . '">' . String::checkPlain('A <link>') . '</a></li>';
     $expected_links .= '<li class="plain-text"><span class="a/class">' . String::checkPlain('Plain "text"') . '</span></li>';
-    $expected_links .= '<li data-drupal-link-system-path="&lt;front&gt;" class="front-page"><a href="' . _url('<front>') . '" data-drupal-link-system-path="&lt;front&gt;">' . String::checkPlain('Front page') . '</a></li>';
+    $expected_links .= '<li data-drupal-link-system-path="&lt;front&gt;" class="front-page"><a href="' . Url::fromRoute('<front>')->toString() . '" data-drupal-link-system-path="&lt;front&gt;">' . String::checkPlain('Front page') . '</a></li>';
     $expected_links .= '<li data-drupal-link-system-path="router_test/test1" class="router-test"><a href="' . \Drupal::urlGenerator()->generate('router_test.1') . '" data-drupal-link-system-path="router_test/test1">' . String::checkPlain('Test route') . '</a></li>';
     $query = array('key' => 'value');
     $encoded_query = String::checkPlain(Json::encode($query));
diff --git a/core/modules/views/src/Tests/GlossaryTest.php b/core/modules/views/src/Tests/GlossaryTest.php
index 61fb6a3..448101c 100644
--- a/core/modules/views/src/Tests/GlossaryTest.php
+++ b/core/modules/views/src/Tests/GlossaryTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\views\Tests;
 
 use Drupal\Component\Utility\Unicode;
+use Drupal\Core\Url;
 use Drupal\views\Views;
 
 /**
@@ -66,7 +67,7 @@ public function testGlossaryView() {
     $this->assertResponse(200);
 
     foreach ($nodes_per_char as $char => $count) {
-      $href = _url('glossary/' . $char);
+      $href = Url::fromRoute('views.glossary.page_1', ['arg_0' => $char]);
       $label = Unicode::strtoupper($char);
       // Get the summary link for a certain character. Filter by label and href
       // to ensure that both of them are correct.
diff --git a/core/modules/views/src/Tests/Wizard/BasicTest.php b/core/modules/views/src/Tests/Wizard/BasicTest.php
index ce4e581..e05bacc 100644
--- a/core/modules/views/src/Tests/Wizard/BasicTest.php
+++ b/core/modules/views/src/Tests/Wizard/BasicTest.php
@@ -75,7 +75,7 @@ function testViewsWizardAndListing() {
     $this->assertText($node2->label());
 
     // Check if we have the feed.
-    $elements = $this->cssSelect('link[href="' . Url::fromUri('base://' . $view2['page[feed_properties][path]'])->toString(), ['absolute' => TRUE]) . '"]');
+    $elements = $this->cssSelect('link[href="' . Url::fromUri('base://' . $view2['page[feed_properties][path]'], ['absolute' => TRUE])->toString() . '"]');
     $this->assertEqual(count($elements), 1, 'Feed found.');
     $this->drupalGet($view2['page[feed_properties][path]']);
     $this->assertRaw('<rss version="2.0"');