test(nutanix): add tests for custom tags support (DataDog#23539)

* test(nutanix): add tests for custom tags support

* test(nutanix): scope to instance tags only

Author: NouemanKHAL

nutanix/tests/test_custom_tags.py

@@ -0,0 +1,35 @@
+# (C) Datadog, Inc. 2026-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+
+
+import pytest
+
+from datadog_checks.nutanix import NutanixCheck
+from tests.constants import (
+    BASE_TAGS,
+    CLUSTER_TAGS,
+    HOST_NAME,
+    HOST_TAGS,
+    PCVM_NAME,
+    PCVM_TAGS,
+)
+
+pytestmark = [pytest.mark.unit]
+
+CUSTOM_TAGS = ['custom_env:test', 'custom_team:agent-integrations', 'custom_key:custom_value']
+
+
+def test_custom_tags_propagate_to_metrics(dd_run_check, aggregator, mock_instance, mock_http_get, datadog_agent):
+    """Custom tags from ``instance['tags']`` propagate to all emitted metrics and external tags."""
+    mock_instance['tags'] = CUSTOM_TAGS
+
+    check = NutanixCheck('nutanix', {}, [mock_instance])
+    dd_run_check(check)
+
+    aggregator.assert_metric("nutanix.health.up", value=1, count=1, tags=BASE_TAGS + CUSTOM_TAGS)
+    aggregator.assert_metric("nutanix.cluster.count", value=1, tags=CLUSTER_TAGS + CUSTOM_TAGS)
+    aggregator.assert_metric("nutanix.host.count", value=1, tags=HOST_TAGS + CUSTOM_TAGS, hostname=HOST_NAME)
+    aggregator.assert_metric("nutanix.vm.count", value=1, tags=PCVM_TAGS + CUSTOM_TAGS)
+    datadog_agent.assert_external_tags(HOST_NAME, {'nutanix': HOST_TAGS + CUSTOM_TAGS})
+    datadog_agent.assert_external_tags(PCVM_NAME, {'nutanix': PCVM_TAGS + CUSTOM_TAGS})