drupalLogin($this->drupalCreateUser(['administer site configuration'])); $page = $this->getSession()->getPage(); $assert_session = $this->assertSession(); $this->drupalGet('admin/structure/config_test/add'); // Test that 'size value' field is not show initially, and it is show after // selecting value in the 'size' field. $this->assertNull($page->findField('size_value')); $page->findField('size')->setValue('custom'); $this->assertNotNull($assert_session->waitForField('size_value')); } }