Unit Test not running

By default, only functions whose name that start with test are run:

class Prueba(unittest.TestCase):

    def setUp(self):
        pass
    def testPrintsTrue(self):
        self.assertTrue(True)

From the unittest basic example:

A testcase is created by subclassing unittest.TestCase. The three individual tests are defined with methods whose names start with the letters test. This naming convention informs the test runner about which methods represent tests.