Assert a metric was processed by this stub

def assert_metric(self, name, value=None, tags=None, count=None, at_least=1, hostname=None, metric_type=None):
        """
        Assert a metric was processed by this stub
        """
        self._asserted.add(name)
        tags = normalize_tags(tags, sort=True)

        candidates = []
        for metric in self.metrics(name):
            if value is not None and not self.is_aggregate(metric.type) and value != metric.value:
                continue

            if tags and tags != sorted(metric.tags):
                continue

            if hostname and hostname != metric.hostname:
                continue

            if metric_type is not None and metric_type != metric.type:
                continue

            candidates.append(metric)

        if value is not None and candidates and all(self.is_aggregate(m.type) for m in candidates):
            got = sum(m.value for m in candidates)
            msg = "Expected count value for '{}': {}, got {}".format(name, value, got)
            assert value == got, msg

        if count is not None:
            msg = "Needed exactly {} candidates for '{}', got {}".format(count, name, len(candidates))
            assert len(candidates) == count, msg
        else:
            msg = "Needed at least {} candidates for '{}', got {}".format(at_least, name, len(candidates))
            assert len(candidates) >= at_least, msg