Test if the usage warning message shows up, when deleting a library item.
public function testLibraryItemDeleteWarningMessage() {
$page = $this
->getSession()
->getPage();
$assert_session = $this
->assertSession();
// Create a paragraph in the library.
$this
->drupalGet('admin/content/paragraphs/add/default');
$page
->pressButton('Add text');
$edit = [
'label[0][value]' => 'Test usage warning message',
'paragraphs[0][subform][field_text][0][value]' => 'Example text.',
];
$this
->submitForm($edit, 'Save');
$assert_session
->pageTextContains('Paragraph Test usage warning message has been created.');
// Create content with referenced paragraph.
$this
->drupalGet('node/add/paragraphed_test');
$page
->pressButton('Add From library');
$edit = [
'title[0][value]' => 'Test content',
'field_paragraphs[0][subform][field_reusable_paragraph][0][target_id]' => 'Test usage warning message',
];
$this
->submitForm($edit, 'Save');
$node = $this
->drupalGetNodeByTitle('Test content');
$library_item = $node
->get('field_paragraphs')->entity
->get('field_reusable_paragraph')->entity;
// Check if there is a warning message on the delete form.
$this
->drupalGet('/admin/content/paragraphs/' . $library_item
->id() . '/delete');
$assert_session
->pageTextContains('There are recorded usages of this entity.');
}