diff -u b/core/modules/taxonomy/src/Tests/VocabularyPermissionsTest.php b/core/modules/taxonomy/src/Tests/VocabularyPermissionsTest.php
--- b/core/modules/taxonomy/src/Tests/VocabularyPermissionsTest.php
+++ b/core/modules/taxonomy/src/Tests/VocabularyPermissionsTest.php
@@ -91,16 +91,16 @@
     // Visit the main taxonomy administration page.
     $this->drupalGet('admin/structure/taxonomy/manage/' . $vocabulary->id() . '/add');
     $this->assertResponse(200);
-    $this->assertField('edit-name', 'Add taxonomy term form opened successfully.');
+    $this->assertFieldByName('name[0][value]', NULL, 'Add taxonomy term form opened successfully.');
 
     // Submit the term.
     $edit = array();
-    $edit['name'] = $this->randomMachineName();
+    $edit['name[0][value]'] = $this->randomMachineName();
 
-    $this->drupalPost(NULL, t('Save'), $edit);
-    $this->assertRaw(t('Created new term %name.', ['%name' => $edit['name']]), 'Term created successfully.');
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->assertRaw(t('Created new term %name.', ['%name' => $edit['name[0][value]']]), 'Term created successfully.');
 
-    $terms = taxonomy_term_load_multiple_by_name($edit['name']);
+    $terms = taxonomy_term_load_multiple_by_name($edit['name[0][value]']);
     $term = reset($terms);
 
     // Edit the term.
@@ -128,7 +128,7 @@
     $this->assertText($term->getName(), 'Edit taxonomy term form opened successfully.');
 
     $edit['name[0][value]'] = $this->randomMachineName();
-    $this->drupalPost(NULL, t('Save'), $edit);
+    $this->drupalPostForm(NULL, $edit, t('Save'));
     $this->assertRaw(t('Updated term %name.', array('%name' => $edit['name[0][value]'])), 'Term updated successfully.');
 
     // Delete the vocabulary.