Remove tests which don't assert anything beyond what the util already does

tests/metrics/test_metrics.py

@@ -26,9 +26,6 @@ from pkg_resources import parse_version
 from prometheus_client.core import Sample
 
 from synapse.metrics import REGISTRY, InFlightGauge, generate_latest
-from synapse.metrics._twisted_exposition import (
-    _set_prometheus_client_use_created_metrics,
-)
 from synapse.util.caches.deferred_cache import DeferredCache
 
 from tests import unittest
@@ -186,30 +183,3 @@ class CacheMetricsTests(unittest.HomeserverTestCase):
 
         self.assertEqual(items["synapse_util_caches_cache_size"], "1.0")
         self.assertEqual(items["synapse_util_caches_cache_max_size"], "777.0")
-
-
-class PrometheusMetricsHackTestCase(unittest.HomeserverTestCase):
-    if parse_version(metadata.version("prometheus_client")) < parse_version("0.14.0"):
-        skip = "prometheus-client too old"
-
-    def test_created_metrics_disabled(self) -> None:
-        """
-        Tests that a brittle hack, to disable `_created` metrics, works.
-        This involves poking at the internals of prometheus-client.
-        It's not the end of the world if this doesn't work.
-
-        This test gives us a way to notice if prometheus-client changes
-        their internals.
-        """
-        import prometheus_client.metrics
-
-        PRIVATE_FLAG_NAME = "_use_created"
-
-        # By default, the pesky `_created` metrics are enabled.
-        # Check this assumption is still valid.
-        self.assertTrue(getattr(prometheus_client.metrics, PRIVATE_FLAG_NAME))
-
-        with patch("prometheus_client.metrics") as mock:
-            setattr(mock, PRIVATE_FLAG_NAME, True)
-            _set_prometheus_client_use_created_metrics(False)
-            self.assertFalse(getattr(mock, PRIVATE_FLAG_NAME, False))