Error with Node_load() - : Base table or view not found
Maybe you should define on the test class what profile are you using. Somehow simpletest does not detect it automatically. Without knowing which profile to install, it will not know what is a laptop node, because this content type has not been created. You can try to define on the test class the attribute:

protected $profile = 'labdoo';


See as an example: https://github.com/dashohoxha/oauth2_client/tree/7.x-1.x/tests

In particular, the shell script can be interesting: https://github.com/dashohoxha/oauth2_client/blob/7.x-1.x/tests/run_tests.sh