post :upload, :id => 2
assert_response :precondition_failed,
"shouldn't be able to upload a invalid deletion diff: #{@response.body}"
+ assert_equal "Precondition failed: Way 3 still used by relation 1.", @response.body
# check that nothing was, in fact, deleted
assert_equal true, Node.find(current_nodes(:node_used_by_relationship).id).visible