assertOffCanvasFormAfterWait example

// Ensure the dragged block is still in the correct position after save.     $page->pressButton('Save layout');
    $assert_session->elementExists('css', '.layout__region--second .block-system-powered-by-block');
    $assert_session->elementTextContains('css', '.layout__region--second', 'Powered by Drupal');

    // Reconfigure a block and ensure that the layout content is updated.     $this->drupalGet($layout_url);
    $this->markCurrentPage();

    $this->clickContextualLink('.block-system-powered-by-block', 'Configure');
    $this->assertOffCanvasFormAfterWait('layout_builder_update_block');

    $page->fillField('settings[label]', 'This is the new label');
    $page->pressButton('Update');
    $assert_session->assertWaitOnAjaxRequest();
    $assert_session->assertNoElementAfterWait('css', '#drupal-off-canvas');

    $assert_session->addressEquals($layout_url);
    $assert_session->pageTextContains('Powered by Drupal');
    $assert_session->pageTextContains('This is the new label');
    $assert_session->pageTextNotContains('This is the label');