This is what I've tried. It seems to work for me:
!python {model: sale.order}: |
assert True, "Testing True!"
assert False, "Testing False!"
(Maybe you forgot the "|" character)
And then :
bin/start_openerp --init=your_module_to_test -d your_testing_database --test-file=/absolute/path/to/your/testing_file.yml
You might want to create your testing database before :
createdb mytestdb --encoding=unicode
Hope it helps you
UPDATE: Here are my logs ( I called my test file sale_order_line_test.yml)
ERROR mytestdb openerp.tools.yaml_import: AssertionError in Python code : Testing False!
mytestdb openerp.modules.loading: At least one test failed when loading the modules.
loading test file /path/to/module/test/sale_order_line_test.yml
AssertionError in Python code : Testing False!