'Assert that one of the strings was logged
Preferable to assertTrue(self._is_logged(..)))
since provides message with the actual log.
Parameters
s : string or list/set/tuple of strings
Test should succeed if string (or any of the listed) is present in the log
all : boolean (default False) if True should fail if any of s not logged'

def assertLogged(self, *s, **kwargs):

    wait = kwargs.get('wait', None)
    if wait:
        res = Utils.wait_for((lambda : self._is_logged(*s, **kwargs)), wait)
    else:
        res = self._is_logged(*s, **kwargs)
    if (not kwargs.get('all', False)):
        if (not res):
            logged = self._log.getvalue()
            self.fail(('None    among    %r    was    found    in    the    log:    ===\n%s===' % (s, logged)))
    elif (not res):
        logged = self._log.getvalue()
        for s_ in s:
            if (s_ not in logged):
                self.fail(('%r    was    not    found    in    the    log:    ===\n%s===' % (s_, logged)))
