chore: add test of ExponentialRateLimitBackends without rate limit

tests/test_exponential_ratelimit_backends.py

@@ -61,3 +61,40 @@ def hook(self, email_messages):
     check(False, '')
     check(False, '')
     check(True, ' (8)')
+
+
+def test_no_exponential_rate_limit(
+    settings, use_exponential_ratelimit_backends, monkeypatch, clear_cache
+):
+    settings.EMAIL_EXPONENTIAL_RATE_LIMIT_TIMEOUT = 0
+    settings.EMAIL_EXPONENTIAL_RATE_LIMIT_BACKENDS = [
+        'django.core.mail.backends.smtp.EmailBackend',
+        'django_ntfy.NtfyBackend',
+    ]
+
+    for _i in range(20):
+        tmp = {"called": False}
+
+        def hook(self, email_messages):
+            assert len(email_messages) == 1
+            assert email_messages[0].subject == "Sub"
+            tmp["called"] = True
+            return 1
+
+        with monkeypatch.context() as m, responses.RequestsMock() as rsps:
+            m.setattr(EmailBackend, 'send_messages', hook)
+            rsps.post(
+                settings.NTFY_BASE_URL,
+                status=200,
+                match=[
+                    matchers.json_params_matcher(
+                        {
+                            "message": "Body",
+                            "title": "Sub",
+                            "topic": "django-ntfy",
+                        }
+                    ),
+                ],
+            )
+            assert mail.send_mail("Sub", "Body", "[email protected]", ["[email protected]"]) == 2
+            assert tmp["called"] is True