'Tries to call all the methods that are listed in the attribute
``install_time_test_callbacks`` if ``self.run_tests is True``.
If ``install_time_test_callbacks is None`` returns immediately.'

@on_package_attributes(run_tests=True)
def _run_default_install_time_test_callbacks(self):

    if (self.install_time_test_callbacks is None):
        return
    for name in self.install_time_test_callbacks:
        try:
            fn = getattr(self, name)
            tty.msg('RUN-TESTS:    install-time    tests    [{0}]'.format(name))
            fn()
        except AttributeError:
            msg = 'RUN-TESTS:    method    not    implemented    [{0}]'
            tty.warn(msg.format(name))
