+
+ $this->drupalGet('admin/config/content/formats/add');
+ // Now attempt to add another filter format with the same editor and same
+ // machine name.
+ $edit = [
+ 'format' => 'filtered_html',
+ 'name' => 'Filtered HTML',
+ 'editor[editor]' => 'ckeditor',
+ ];
+ $this->submitForm($edit, 'editor_configure');
+ $this->submitForm($edit, 'Save configuration');
+ $this->assertResponse(200);
+ $this->assertText('The machine-readable name is already in use. It must be unique.');