[cilium] strengthen tests to lift mutation score (DataDog#23752)

* [cilium] add env-agnostic unit tests to lift mutation score

The existing tests/test_cilium.py is gated by requires_new_environment,
so it skips entirely under the legacy hatch env and runs only a thin
slice under the modern env. This left CiliumCheckV2._parse_config,
the legacy CiliumCheck __new__/__init__ routing, and
construct_metrics_config's suffix stripping with 0% mutation coverage.

Add tests/test_unit.py with 29 env-agnostic tests covering:

- construct_metrics_config: _total / _counter suffix stripping,
  passthrough, empty input, iteration, substring-not-suffix.
- CiliumCheckV2._parse_config: DEFAULT_METRIC_LIMIT, missing-endpoint
  validation, agent-only / operator-only / both scraper construction,
  agent-vs-operator metric set selection.
- Legacy CiliumCheck: __new__ routing on use_openmetrics (truthy /
  falsy / absent / first-instance), __init__ validation
  (both / neither endpoint), first-instance endpoint selection,
  operator vs agent metric set, default and custom prometheus_timeout,
  namespace, metadata_metric_name.

Local cosmic-ray run with --test-path tests/test_unit.py:
51 mutants generated, 51 killed, 0 survived (100% from 0%).

* [cilium] Replace repr-based metric-set assertions with structural key iteration

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: philjlee

cilium/tests/test_unit.py

@@ -0,0 +1,212 @@
+# (C) Datadog, Inc. 2026-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+import pytest
+
+from datadog_checks.base import ConfigurationError
+from datadog_checks.cilium import CiliumCheck
+from datadog_checks.cilium.check import CiliumCheckV2
+from datadog_checks.cilium.cilium import CiliumCheck as LegacyCiliumCheck
+from datadog_checks.cilium.metrics import construct_metrics_config
+
+pytestmark = pytest.mark.unit
+
+
+def test_construct_metrics_config_strips_total_suffix():
+    out = construct_metrics_config({"cilium_drop_count_total": "drop_count.total"})
+    assert out == [{"cilium_drop_count": {"name": "drop_count"}}]
+
+
+def test_construct_metrics_config_strips_counter_suffix():
+    out = construct_metrics_config({"cilium_api_counter": "api.counter"})
+    assert out == [{"cilium_api": {"name": "api"}}]
+
+
+def test_construct_metrics_config_passes_through_when_no_suffix():
+    out = construct_metrics_config({"cilium_endpoint": "endpoint.count"})
+    assert out == [{"cilium_endpoint": {"name": "endpoint.count"}}]
+
+
+def test_construct_metrics_config_empty_map_returns_empty_list():
+    assert construct_metrics_config({}) == []
+
+
+def test_construct_metrics_config_iterates_every_entry():
+    out = construct_metrics_config(
+        {
+            "a_total": "a.total",
+            "b_counter": "b.counter",
+            "c": "c",
+        }
+    )
+    assert len(out) == 3
+    assert {"a": {"name": "a"}} in out
+    assert {"b": {"name": "b"}} in out
+    assert {"c": {"name": "c"}} in out
+
+
+def test_construct_metrics_config_total_substring_not_stripped():
+    # "_total" must be a suffix; the substring elsewhere stays intact.
+    out = construct_metrics_config({"totally_random": "totally.random"})
+    assert out == [{"totally_random": {"name": "totally.random"}}]
+
+
+def test_construct_metrics_config_counter_substring_not_stripped():
+    out = construct_metrics_config({"countermeasure": "countermeasure"})
+    assert out == [{"countermeasure": {"name": "countermeasure"}}]
+
+
+def test_v2_default_metric_limit_is_zero():
+    assert CiliumCheckV2.DEFAULT_METRIC_LIMIT == 0
+
+
+def test_v2_raises_when_neither_endpoint_set():
+    check = CiliumCheckV2("cilium", {}, [{}])
+    with pytest.raises(ConfigurationError, match="Must specify at least one"):
+        check._parse_config()
+
+
+def test_v2_agent_endpoint_only_builds_one_scraper_pointing_at_agent():
+    check = CiliumCheckV2("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    check._parse_config()
+    assert len(check.scraper_configs) == 1
+    assert check.scraper_configs[0]["openmetrics_endpoint"] == "http://agent/metrics"
+
+
+def test_v2_operator_endpoint_only_builds_one_scraper_pointing_at_operator():
+    check = CiliumCheckV2("cilium", {}, [{"operator_endpoint": "http://op/metrics"}])
+    check._parse_config()
+    assert len(check.scraper_configs) == 1
+    assert check.scraper_configs[0]["openmetrics_endpoint"] == "http://op/metrics"
+
+
+def test_v2_both_endpoints_build_two_scrapers():
+    check = CiliumCheckV2(
+        "cilium",
+        {},
+        [{"agent_endpoint": "http://agent/metrics", "operator_endpoint": "http://op/metrics"}],
+    )
+    check._parse_config()
+    endpoints = sorted(s["openmetrics_endpoint"] for s in check.scraper_configs)
+    assert endpoints == ["http://agent/metrics", "http://op/metrics"]
+
+
+def test_v2_agent_scraper_uses_agent_metrics_not_operator():
+    check = CiliumCheckV2("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    check._parse_config()
+    metric_keys = {next(iter(m)) for m in check.scraper_configs[0]["metrics"]}
+    assert "cilium_drop_count" in metric_keys
+    assert not any(name.startswith("cilium_operator_eni_") for name in metric_keys)
+
+
+def test_v2_operator_scraper_uses_operator_metrics_not_agent():
+    check = CiliumCheckV2("cilium", {}, [{"operator_endpoint": "http://op/metrics"}])
+    check._parse_config()
+    metric_keys = {next(iter(m)) for m in check.scraper_configs[0]["metrics"]}
+    assert any(name.startswith("cilium_operator_") for name in metric_keys)
+    assert "cilium_drop_count" not in metric_keys
+
+
+def test_legacy_default_metric_limit_is_zero():
+    assert LegacyCiliumCheck.DEFAULT_METRIC_LIMIT == 0
+
+
+def test_legacy_routes_to_v2_when_use_openmetrics_is_truthy():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics", "use_openmetrics": True}])
+    assert isinstance(check, CiliumCheckV2)
+
+
+def test_legacy_routes_to_legacy_when_use_openmetrics_is_falsy():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics", "use_openmetrics": False}])
+    assert not isinstance(check, CiliumCheckV2)
+
+
+def test_legacy_default_use_openmetrics_routes_to_legacy():
+    # When the key is absent, the get() default must be False so we stay on legacy.
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    assert not isinstance(check, CiliumCheckV2)
+
+
+def test_legacy_new_picks_first_instance_for_routing_legacy_path():
+    check = CiliumCheck(
+        "cilium",
+        {},
+        [
+            {"agent_endpoint": "http://agent/metrics", "use_openmetrics": False},
+            {"agent_endpoint": "http://agent2/metrics", "use_openmetrics": True},
+        ],
+    )
+    assert not isinstance(check, CiliumCheckV2)
+
+
+def test_legacy_new_picks_first_instance_for_routing_v2_path():
+    check = CiliumCheck(
+        "cilium",
+        {},
+        [
+            {"agent_endpoint": "http://agent/metrics", "use_openmetrics": True},
+            {"agent_endpoint": "http://agent2/metrics", "use_openmetrics": False},
+        ],
+    )
+    assert isinstance(check, CiliumCheckV2)
+
+
+def test_legacy_raises_when_both_endpoints_set():
+    with pytest.raises(ConfigurationError, match="Only one endpoint needs to be specified"):
+        CiliumCheck(
+            "cilium",
+            {},
+            [{"agent_endpoint": "http://agent/metrics", "operator_endpoint": "http://op/metrics"}],
+        )
+
+
+def test_legacy_raises_when_neither_endpoint_set():
+    with pytest.raises(ConfigurationError, match="Must provide at least one endpoint"):
+        CiliumCheck("cilium", {}, [{}])
+
+
+def test_legacy_init_uses_first_instance_for_endpoint_choice():
+    check = CiliumCheck(
+        "cilium",
+        {},
+        [
+            {"agent_endpoint": "http://first/metrics"},
+            {"agent_endpoint": "http://second/metrics"},
+        ],
+    )
+    assert check.instance["prometheus_url"] == "http://first/metrics"
+
+
+def test_legacy_operator_endpoint_selects_operator_metric_set():
+    check = CiliumCheck("cilium", {}, [{"operator_endpoint": "http://op/metrics"}])
+    assert check.instance["prometheus_url"] == "http://op/metrics"
+    metric_keys = {key for m in check.instance["metrics"] for key in m}
+    assert "cilium_operator_process_cpu_seconds_total" in metric_keys
+
+
+def test_legacy_agent_endpoint_selects_agent_metric_set():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    assert check.instance["prometheus_url"] == "http://agent/metrics"
+    metric_keys = {key for m in check.instance["metrics"] for key in m}
+    assert "cilium_drop_count_total" in metric_keys
+    assert "cilium_operator_eni_available" not in metric_keys
+
+
+def test_legacy_default_prometheus_timeout_is_10():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    assert check.instance["prometheus_timeout"] == 10
+
+
+def test_legacy_custom_timeout_passes_through():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics", "timeout": 42}])
+    assert check.instance["prometheus_timeout"] == 42
+
+
+def test_legacy_namespace_is_cilium():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    assert check.instance["namespace"] == "cilium"
+
+
+def test_legacy_metadata_metric_name_is_cilium_version():
+    check = CiliumCheck("cilium", {}, [{"agent_endpoint": "http://agent/metrics"}])
+    assert check.instance["metadata_metric_name"] == "cilium_version"