Add assertMetricNotEquals (#385)

Author: asherf

django_prometheus/tests/test_testutils.py

@@ -67,14 +67,10 @@ def testAssertMetricEquals(self):
         # First we test that a scalar metric can be tested.
         self.test_case.assertMetricEquals(42, "some_gauge", registry=self.registry)
         assert self.test_case.passes is True
-        self.test_case.assertMetricEquals(43, "some_gauge", registry=self.registry)
-        assert self.test_case.passes is False
-        self.test_case.passes = True
+        self.test_case.assertMetricNotEquals(43, "some_gauge", registry=self.registry)
 
         # Here we test that assertMetricEquals fails on nonexistent gauges.
-        self.test_case.assertMetricEquals(42, "some_nonexistent_gauge", registry=self.registry)
-        assert not self.test_case.passes
-        self.test_case.passes = True
+        self.test_case.assertMetricNotEquals(42, "some_nonexistent_gauge", registry=self.registry)
 
         # Here we test that labelled metrics can be tested.
         self.test_case.assertMetricEquals(
@@ -85,15 +81,13 @@ def testAssertMetricEquals(self):
             labelblue="indigo",
         )
         assert self.test_case.passes is True
-        self.test_case.assertMetricEquals(
+        self.test_case.assertMetricNotEquals(
             1,
             "some_labelled_gauge",
             registry=self.registry,
             labelred="tomato",
             labelblue="sky",
         )
-        assert self.test_case.passes is False
-        self.test_case.passes = True
 
     def testRegistrySaving(self):
         """Tests saveRegistry and frozen registries operations."""

django_prometheus/testutils.py

@@ -103,6 +103,19 @@ def assertMetricEquals(self, expected_value, metric_name, registry=REGISTRY, **l
         )
         self.assertEqual(expected_value, value, assert_err)
 
+    def assertMetricNotEquals(self, expected_value, metric_name, registry=REGISTRY, **labels):
+        """Asserts that metric_name{**labels} == expected_value."""
+        value = self.getMetric(metric_name, registry=registry, **labels)
+        assert_err = METRIC_EQUALS_ERR_EXPLANATION % (
+            metric_name,
+            self.formatLabels(labels),
+            value,
+            expected_value,
+            metric_name,
+            self.formatVector(self.getMetricVector(metric_name)),
+        )
+        assert expected_value != value, assert_err
+
     def assertMetricDiff(self, frozen_registry, expected_diff, metric_name, registry=REGISTRY, **labels):
         """Asserts that metric_name{**labels} changed by expected_diff between
         the frozen registry and now. A frozen registry can be obtained