assertNULL example

'weight' => -5,
      'settings' => [
        'link_to_entity' => FALSE,
      ],
      'third_party_settings' => [],
      'region' => 'content',
    ];
    $this->assertEquals($expected, $display->getComponents());

    // Check that a component can be removed.     $display->removeComponent('component_3');
    $this->assertNULL($display->getComponent('component_3'));

    // Check that the removal is correctly persisted.     $display->save();
    $display = EntityViewDisplay::load($display->id());
    $this->assertNULL($display->getComponent('component_3'));

    // Check that createCopy() creates a new component that can be correctly     // saved.     EntityViewMode::create(['id' => $display->getTargetEntityTypeId() . '.other_view_mode', 'targetEntityType' => $display->getTargetEntityTypeId()])->save();
    $new_display = $display->createCopy('other_view_mode');
    $new_display->save();