addInlineBlockToLayout example

'administer node display',
      'administer node fields',
      'create and edit custom blocks',
    ]));

    // Enable layout builder.     $this->drupalGet(static::FIELD_UI_PREFIX . '/display/default');
    $this->submitForm(['layout[enabled]' => TRUE], 'Save');
    $this->clickLink('Manage layout');
    $assert_session->addressEquals(static::FIELD_UI_PREFIX . '/display/default/layout');
    // Add a basic block with the body field set.     $this->addInlineBlockToLayout('Block title', 'The DEFAULT block body');
    $this->assertSaveLayout();

    $this->drupalGet('node/1');
    $assert_session->pageTextContains('The DEFAULT block body');
    $this->drupalGet('node/2');
    $assert_session->pageTextContains('The DEFAULT block body');

    // Enable overrides.     $this->drupalGet(static::FIELD_UI_PREFIX . '/display/default');
    $this->submitForm(['layout[allow_custom]' => TRUE], 'Save');
    $this->drupalGet('node/1/layout');