Fix failed metric names.

Previously, the failed metric had "collector" twice in its name.
Eg: "ipmidcmicollector_collector_failed"

This change aims to remove the duplication.
Previous example becomes "ipmidcmi_collector_failed"

The label is also changed similarly to reflect the new name.

Unit test was also modified to reflect this change.

prometheus_hardware_exporter/core.py

@@ -96,14 +96,18 @@ def failed_metrics(self) -> Iterable[Metric]:
         Yields:
             metrics: the internal metrics
         """
-        name = self.__class__.__name__
+        # if `__class_.__name__` is "IpmiDcmiCollector"
+        # then `name` becomes "ipmidcmi"
+        suffix = "collector"
+        class_name = self.__class__.__name__.lower()
+        name = class_name[: -len(suffix)] if class_name.endswith(suffix) else class_name
         metric = GaugeMetricFamily(
-            name=f"{name.lower()}_collector_failed",
-            documentation=f"{name} Collector failed to fetch metrics",
+            name=f"{name}_collector_failed",
+            documentation=f"{name} collector failed to fetch metrics",
             labels=["collector"],
         )
         metric.add_metric(
-            labels=[self.__class__.__name__],
+            labels=[name],
             value=1,
         )
         yield metric

tests/unit/test_collector.py

@@ -1297,18 +1297,18 @@ def test_collector_fetch_failed(self):
         for collector_cls, expected_name, expected_labels in [
             (
                 MegaRAIDCollector,
-                "megaraidcollector_collector_failed",
-                {"collector": "MegaRAIDCollector"},
+                "megaraid_collector_failed",
+                {"collector": "megaraid"},
             ),
             (
                 RedfishCollector,
-                "redfishcollector_collector_failed",
-                {"collector": "RedfishCollector"},
+                "redfish_collector_failed",
+                {"collector": "redfish"},
             ),
             (
                 IpmiSensorsCollector,
-                "ipmisensorscollector_collector_failed",
-                {"collector": "IpmiSensorsCollector"},
+                "ipmisensors_collector_failed",
+                {"collector": "ipmisensors"},
             ),
         ]:
             collector = collector_cls(Mock())