Move assert_metric_equal out of base class (#390)

Author: asherf

django_prometheus/tests/end2end/testapp/test_caches.py

@@ -2,10 +2,10 @@
 from django.test import TestCase
 from redis import RedisError
 
-from django_prometheus.testutils import PrometheusTestCaseMixin, get_metric
+from django_prometheus.testutils import assert_metric_equal, get_metric
 
 
-class TestCachesMetrics(PrometheusTestCaseMixin, TestCase):
+class TestCachesMetrics(TestCase):
     """Test django_prometheus.caches metrics."""
 
     def test_counters(self):
@@ -35,9 +35,9 @@ def test_counters(self):
 
             assert result == "default"
 
-            self.assertMetricEquals(total_before + 4, "django_cache_get_total", backend=backend)
-            self.assertMetricEquals(hit_before + 2, "django_cache_get_hits_total", backend=backend)
-            self.assertMetricEquals(
+            assert_metric_equal(total_before + 4, "django_cache_get_total", backend=backend)
+            assert_metric_equal(hit_before + 2, "django_cache_get_hits_total", backend=backend)
+            assert_metric_equal(
                 miss_before + 2,
                 "django_cache_get_misses_total",
                 backend=backend,
@@ -55,19 +55,19 @@ def test_redis_cache_fail(self):
         tested_cache = caches["stopped_redis_ignore_exception"]
         tested_cache.get("foo1")
 
-        self.assertMetricEquals(hit_before, "django_cache_get_hits_total", backend=supported_cache)
-        self.assertMetricEquals(miss_before, "django_cache_get_misses_total", backend=supported_cache)
-        self.assertMetricEquals(total_before + 1, "django_cache_get_total", backend=supported_cache)
-        self.assertMetricEquals(fail_before + 1, "django_cache_get_fail_total", backend=supported_cache)
+        assert_metric_equal(hit_before, "django_cache_get_hits_total", backend=supported_cache)
+        assert_metric_equal(miss_before, "django_cache_get_misses_total", backend=supported_cache)
+        assert_metric_equal(total_before + 1, "django_cache_get_total", backend=supported_cache)
+        assert_metric_equal(fail_before + 1, "django_cache_get_fail_total", backend=supported_cache)
 
         tested_cache = caches["stopped_redis"]
         with self.assertRaises(RedisError):
             tested_cache.get("foo1")
 
-        self.assertMetricEquals(hit_before, "django_cache_get_hits_total", backend=supported_cache)
-        self.assertMetricEquals(miss_before, "django_cache_get_misses_total", backend=supported_cache)
-        self.assertMetricEquals(total_before + 2, "django_cache_get_total", backend=supported_cache)
-        self.assertMetricEquals(fail_before + 2, "django_cache_get_fail_total", backend=supported_cache)
+        assert_metric_equal(hit_before, "django_cache_get_hits_total", backend=supported_cache)
+        assert_metric_equal(miss_before, "django_cache_get_misses_total", backend=supported_cache)
+        assert_metric_equal(total_before + 2, "django_cache_get_total", backend=supported_cache)
+        assert_metric_equal(fail_before + 2, "django_cache_get_fail_total", backend=supported_cache)
 
     def test_cache_version_support(self):
         supported_caches = [

django_prometheus/tests/end2end/testapp/test_db.py

@@ -4,15 +4,15 @@
 from django.test import TestCase
 
 from django_prometheus.testutils import (
-    PrometheusTestCaseMixin,
     assert_metric_compare,
     assert_metric_diff,
+    assert_metric_equal,
     get_metric,
     save_registry,
 )
 
 
-class BaseDbMetricTest(PrometheusTestCaseMixin, TestCase):
+class BaseDbMetricTest(TestCase):
     # https://docs.djangoproject.com/en/2.2/topics/testing/tools/#django.test.SimpleTestCase.databases
     databases = "__all__"
 
@@ -47,7 +47,7 @@ def test_counters(self):
         except Exception:
             pass
 
-        self.assertMetricEquals(
+        assert_metric_equal(
             1,
             "django_db_errors_total",
             alias="test_db_1",

django_prometheus/tests/end2end/testapp/test_middleware.py

@@ -2,8 +2,8 @@
 from testapp.views import ObjectionException
 
 from django_prometheus.testutils import (
-    PrometheusTestCaseMixin,
     assert_metric_diff,
+    assert_metric_equal,
     save_registry,
 )
 
@@ -25,7 +25,7 @@ def T(metric_name):
 
 
 @override_settings(PROMETHEUS_LATENCY_BUCKETS=(0.05, 1.0, 2.0, 4.0, 5.0, 10.0, float("inf")))
-class TestMiddlewareMetrics(PrometheusTestCaseMixin, SimpleTestCase):
+class TestMiddlewareMetrics(SimpleTestCase):
     """Test django_prometheus.middleware.
 
     Note that counters related to exceptions can't be tested as
@@ -74,7 +74,7 @@ def test_request_counters(self):
         # <=128 bytes bodies.
         assert_metric_diff(registry, 3, M("requests_body_total_bytes_bucket"), le="0.0")
         assert_metric_diff(registry, 4, M("requests_body_total_bytes_bucket"), le="128.0")
-        self.assertMetricEquals(None, M("responses_total_by_templatename"), templatename="help.html")
+        assert_metric_equal(None, M("responses_total_by_templatename"), templatename="help.html")
         assert_metric_diff(registry, 3, T("responses_total_by_templatename"), templatename="index.html")
         assert_metric_diff(registry, 4, T("responses_total_by_status"), status="200")
         assert_metric_diff(registry, 0, M("responses_body_total_bytes_bucket"), le="0.0")

django_prometheus/tests/end2end/testapp/test_middleware_custom_labels.py

@@ -9,11 +9,7 @@
     PrometheusAfterMiddleware,
     PrometheusBeforeMiddleware,
 )
-from django_prometheus.testutils import (
-    PrometheusTestCaseMixin,
-    assert_metric_diff,
-    save_registry,
-)
+from django_prometheus.testutils import assert_metric_diff, save_registry
 
 EXTENDED_METRICS = [
     M("requests_latency_seconds_by_view_method"),
@@ -49,7 +45,7 @@ def label_metric(self, metric, request, response=None, **labels):
         "testapp.test_middleware_custom_labels.AppMetricsAfterMiddleware",
     )
 )
-class TestMiddlewareMetricsWithCustomLabels(PrometheusTestCaseMixin, SimpleTestCase):
+class TestMiddlewareMetricsWithCustomLabels(SimpleTestCase):
     @classmethod
     def setUpClass(cls):
         super().setUpClass()

django_prometheus/tests/end2end/testapp/test_migrations.py

@@ -3,7 +3,7 @@
 from django.test import SimpleTestCase
 
 from django_prometheus.migrations import ExportMigrationsForDatabase
-from django_prometheus.testutils import PrometheusTestCaseMixin
+from django_prometheus.testutils import assert_metric_equal
 
 
 def M(metric_name):
@@ -15,7 +15,7 @@ def M(metric_name):
     return "django_migrations_%s" % metric_name
 
 
-class TestMigrations(PrometheusTestCaseMixin, SimpleTestCase):
+class TestMigrations(SimpleTestCase):
     """Test migration counters."""
 
     def test_counters(self):
@@ -30,7 +30,7 @@ def test_counters(self):
         executor.loader.applied_migrations = {"b", "c"}
         ExportMigrationsForDatabase("fakedb2", executor)
 
-        self.assertMetricEquals(3, M("applied_total"), connection="fakedb1")
-        self.assertMetricEquals(0, M("unapplied_total"), connection="fakedb1")
-        self.assertMetricEquals(2, M("applied_total"), connection="fakedb2")
-        self.assertMetricEquals(1, M("unapplied_total"), connection="fakedb2")
+        assert_metric_equal(3, M("applied_total"), connection="fakedb1")
+        assert_metric_equal(0, M("unapplied_total"), connection="fakedb1")
+        assert_metric_equal(2, M("applied_total"), connection="fakedb2")
+        assert_metric_equal(1, M("unapplied_total"), connection="fakedb2")

django_prometheus/tests/end2end/testapp/test_models.py

@@ -1,11 +1,7 @@
 from django.test import TestCase
 from testapp.models import Dog, Lawn
 
-from django_prometheus.testutils import (
-    PrometheusTestCaseMixin,
-    assert_metric_diff,
-    save_registry,
-)
+from django_prometheus.testutils import assert_metric_diff, save_registry
 
 
 def M(metric_name):
@@ -17,7 +13,7 @@ def M(metric_name):
     return "django_model_%s" % metric_name
 
 
-class TestModelMetrics(PrometheusTestCaseMixin, TestCase):
+class TestModelMetrics(TestCase):
     """Test django_prometheus.models."""
 
     def test_counters(self):

django_prometheus/tests/test_testutils.py

@@ -5,8 +5,8 @@
 import prometheus_client
 
 from django_prometheus.testutils import (
-    PrometheusTestCaseMixin,
     assert_metric_diff,
+    assert_metric_equal,
     assert_metric_no_diff,
     assert_metric_not_equal,
     get_metric,
@@ -16,17 +16,6 @@
 )
 
 
-class SomeTestCase(PrometheusTestCaseMixin):
-    """A class that pretends to be a unit test."""
-
-    def __init__(self):
-        self.passes = True
-        super().__init__()
-
-    def assertEqual(self, left, right, *args, **kwargs):
-        self.passes = self.passes and (left == right)
-
-
 class PrometheusTestCaseMixinTest(unittest.TestCase):
     def setUp(self):
         self.registry = prometheus_client.CollectorRegistry()
@@ -42,7 +31,6 @@ def setUp(self):
         self.some_labelled_gauge.labels("pink", "royal").set(2)
         self.some_labelled_gauge.labels("carmin", "indigo").set(3)
         self.some_labelled_gauge.labels("carmin", "royal").set(4)
-        self.test_case = SomeTestCase()
 
     def test_get_metric(self):
         """Tests get_metric."""
@@ -71,25 +59,25 @@ def test_get_metrics_vector(self):
             key=itemgetter(1),
         ) == sorted(vector, key=itemgetter(1))
 
-    def testAssertMetricEquals(self):
-        """Tests assertMetricEquals."""
+    def test_assert_metric_equal(self):
+        """Tests assert_metric_equal."""
         # 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
+        assert_metric_equal(42, "some_gauge", registry=self.registry)
+
         assert_metric_not_equal(43, "some_gauge", registry=self.registry)
 
-        # Here we test that assertMetricEquals fails on nonexistent gauges.
+        # Here we test that assert_metric_equal fails on nonexistent gauges.
         assert_metric_not_equal(42, "some_nonexistent_gauge", registry=self.registry)
 
         # Here we test that labelled metrics can be tested.
-        self.test_case.assertMetricEquals(
+        assert_metric_equal(
             1,
             "some_labelled_gauge",
             registry=self.registry,
             labelred="pink",
             labelblue="indigo",
         )
-        assert self.test_case.passes is True
+
         assert_metric_not_equal(
             1,
             "some_labelled_gauge",

django_prometheus/testutils.py

@@ -26,23 +26,23 @@
 """
 
 
-class PrometheusTestCaseMixin:
-    """A collection of utilities that make it easier to write test cases
-    that interact with metrics.
-    """
+"""A collection of utilities that make it easier to write test cases
+that interact with metrics.
+"""
 
-    def assertMetricEquals(self, expected_value, metric_name, registry=REGISTRY, **labels):
-        """Asserts that metric_name{**labels} == expected_value."""
-        value = get_metric(metric_name, registry=registry, **labels)
-        assert_err = METRIC_EQUALS_ERR_EXPLANATION % (
-            metric_name,
-            format_labels(labels),
-            value,
-            expected_value,
-            metric_name,
-            format_vector(get_metrics_vector(metric_name)),
-        )
-        assert expected_value == value, assert_err
+
+def assert_metric_equal(expected_value, metric_name, registry=REGISTRY, **labels):
+    """Asserts that metric_name{**labels} == expected_value."""
+    value = get_metric(metric_name, registry=registry, **labels)
+    assert_err = METRIC_EQUALS_ERR_EXPLANATION % (
+        metric_name,
+        format_labels(labels),
+        value,
+        expected_value,
+        metric_name,
+        format_vector(get_metrics_vector(metric_name)),
+    )
+    assert expected_value == value, assert_err
 
 
 def assert_metric_diff(frozen_registry, expected_diff, metric_name, registry=REGISTRY, **labels):