test(deps): add prometheus client dependency and monitoring unit test

Author: rondinelisaad

requirements.txt

@@ -15,3 +15,4 @@ publicationstatsapi
 articlemetaapi
 altmetric
 tenacity
+prometheus_client

tests/test_monitoring.py

@@ -0,0 +1,10 @@
+import unittest
+
+from analytics import monitoring
+
+
+class MonitoringTest(unittest.TestCase):
+    def test_metrics_response_contains_http_metric(self):
+        body, content_type = monitoring.metrics_response()
+        self.assertTrue(content_type.startswith("text/plain; version="))
+        self.assertIn(b"analytics_http_requests_total", body)