How to mock custom block in magento ecomdev test case

i'm trying to test my block method with magento ecomdev phpunit. I have block like this:

<block type="airhotels/property_view_amenities" name="airhotels.property.view.amenities" template="airhotels/property/view/amenities.phtml" />

I'm trying to get block:

$block = $this->getBlockMock('airhotels/property_view_amenities');

and after this line my all tests stop working.

Can someone explain me how to mock block in ecomdev and test methods of this mocked block?