[kong] strengthen tests to lift mutation score (DataDog#24334)

Author: philjlee

kong/tests/test_unit.py

@@ -1,17 +1,22 @@
 # (C) Datadog, Inc. 2021-present
 # All rights reserved
 # Licensed under a 3-clause BSD style license (see LICENSE)
+import json
 import os
+from collections import namedtuple
 
 import pytest
 
 from datadog_checks.dev.utils import get_metadata_metrics
 from datadog_checks.kong import Kong
+from datadog_checks.kong.check import KongCheck
 
-from .common import HERE, METRICS_URL
+from .common import HERE, METRICS_URL, STATUS_URL
 
 pytestmark = [pytest.mark.unit]
 
+FakeSample = namedtuple('FakeSample', ['value', 'labels'])
+
 EXPECTED_METRICS = {
     'kong.bandwidth.count': 'monotonic_count',
     'kong.http.consumer.status.count': 'monotonic_count',
@@ -115,3 +120,119 @@ def test_check(aggregator, dd_run_check, mock_http_response):
         tags=['address:localhost:1004', 'endpoint:{}'.format(METRICS_URL), 'target:target4', 'upstream:upstream4'],
         count=1,
     )
+
+
+def test_v2_default_metric_limit_is_zero():
+    # Kills the core/NumberReplacer mutant at check.py:12 (DEFAULT_METRIC_LIMIT 0 -> -1).
+    assert KongCheck.DEFAULT_METRIC_LIMIT == 0
+
+
+def test_v2_transformer_only_processes_sample_with_value_exactly_one(aggregator):
+    # Kills the core/ReplaceComparisonOperator_NotEq_Lt mutant at check.py:28 (sample.value != 1 -> < 1).
+    check = KongCheck('kong', {}, [{'openmetrics_endpoint': METRICS_URL}])
+    service_check = check.configure_transformer_upstream_target_health()
+
+    sample = FakeSample(value=2, labels={'state': 'healthy'})
+    service_check(None, [(sample, ['state:healthy'], 'host1')], None)
+
+    assert len(aggregator.service_checks('kong.upstream.target.health')) == 0
+
+
+def test_v2_transformer_processes_samples_after_skipping_one(aggregator):
+    # Kills the core/ReplaceContinueWithBreak mutant at check.py:29 (continue -> break drops later samples).
+    check = KongCheck('kong', {}, [{'openmetrics_endpoint': METRICS_URL}])
+    service_check = check.configure_transformer_upstream_target_health()
+
+    sample_data = [
+        (FakeSample(value=2, labels={'state': 'irrelevant'}), ['state:irrelevant'], 'host1'),
+        (FakeSample(value=1, labels={'state': 'healthy'}), ['state:healthy'], 'host2'),
+    ]
+    service_check(None, sample_data, None)
+
+    aggregator.assert_service_check(
+        'kong.upstream.target.health', status=KongCheck.OK, tags=[], hostname='host2', count=1
+    )
+
+
+def test_legacy_new_uses_first_instance_to_choose_check_class():
+    # Kills the core/NumberReplacer mutant at kong.py:25 (instances[0] -> instances[-1]).
+    check = Kong('kong', {}, [{'openmetrics_endpoint': METRICS_URL}, {'kong_status_url': STATUS_URL}])
+    assert isinstance(check, KongCheck)
+
+
+def test_legacy_fetch_data_raises_when_status_url_missing():
+    # Kills the core/AddNot mutant at kong.py:42 (double negation flips the missing-config check).
+    check = Kong('kong', {}, [{'tags': []}])
+    with pytest.raises(Exception, match='missing "kong_status_url" value'):
+        check._fetch_data()
+
+
+def test_legacy_fetch_data_can_connect_tags_use_default_port_and_appended_tags(
+    aggregator, dd_run_check, mock_http_response
+):
+    # Kills the core/NumberReplacer and ReplaceOrWithAnd mutants at kong.py:49 (default port 80 -> 79/81 or "or"->"and")
+    # and the ReplaceBinaryOperator_Add_* / ReplaceBinaryOperator_Mod_* mutants at kong.py:51
+    # (tag list "+" and the "%" string formatting inside it).
+    mock_http_response(json_data={'server': {}})
+    instance = {'kong_status_url': 'http://myhost/status/', 'tags': ['env:test']}
+    check = Kong('kong', {}, [instance])
+    dd_run_check(check)
+
+    aggregator.assert_service_check(
+        'kong.can_connect', status=Kong.OK, tags=['kong_host:myhost', 'kong_port:80', 'env:test'], count=1
+    )
+
+
+def test_legacy_parse_json_defaults_tags_and_prefixes_metric_names():
+    # Kills the core/ReplaceComparisonOperator_Is_IsNot and AddNot mutants at kong.py:70 (tags is None check),
+    # the ZeroIterationForLoop mutant at kong.py:76, and the ReplaceBinaryOperator_Add_* mutants at kong.py:77.
+    check = Kong('kong', {}, [{'kong_status_url': 'http://myhost/status/'}])
+    raw = json.dumps({'server': {'total_requests': 42}}).encode('utf-8')
+
+    output = check._parse_json(raw)
+
+    assert output == [('kong.total_requests', 42, [])]
+
+
+def test_legacy_check_continues_after_metric_submission_error(aggregator, dd_run_check, mock_http_response):
+    # Kills the core/ZeroIterationForLoop mutant at kong.py:34 and the ExceptionReplacer mutant at kong.py:38
+    # (a bad metric value must not stop later metrics in the loop from being submitted).
+    mock_http_response(json_data={'server': {'bad_metric': 'oops', 'good_metric': 5}})
+    instance = {'kong_status_url': 'http://myhost/status/', 'tags': []}
+    check = Kong('kong', {}, [instance])
+    dd_run_check(check)
+
+    aggregator.assert_metric('kong.good_metric', value=5, count=1)
+    aggregator.assert_metric('kong.bad_metric', count=0)
+
+
+def test_legacy_check_submits_critical_service_check_on_http_error(aggregator, mock_http_response):
+    # Kills the core/ExceptionReplacer mutant at kong.py:58 (except Exception -> except CosmicRayTestingException).
+    mock_http_response(status_code=500)
+    instance = {'kong_status_url': 'http://myhost/status/', 'tags': []}
+    check = Kong('kong', {}, [instance])
+
+    with pytest.raises(Exception):
+        check.check(None)
+
+    aggregator.assert_service_check('kong.can_connect', status=Kong.CRITICAL, count=1)
+
+
+def test_legacy_check_treats_status_code_below_200_as_critical(aggregator, mock_http_response):
+    # Kills the core/ReplaceComparisonOperator_Eq_LtE mutant at kong.py:62 (status_code == 200 -> <= 200).
+    mock_http_response(status_code=100, json_data={'server': {}})
+    instance = {'kong_status_url': 'http://myhost/status/', 'tags': []}
+    check = Kong('kong', {}, [instance])
+    check.check(None)
+
+    aggregator.assert_service_check('kong.can_connect', status=Kong.CRITICAL, count=1)
+
+
+def test_legacy_check_treats_status_code_above_200_as_critical(aggregator, mock_http_response):
+    # Kills the core/ReplaceComparisonOperator_Eq_GtE mutant at kong.py:62 (status_code == 200 -> >= 200).
+    mock_http_response(status_code=204, json_data={'server': {}})
+    instance = {'kong_status_url': 'http://myhost/status/', 'tags': []}
+    check = Kong('kong', {}, [instance])
+    check.check(None)
+
+    aggregator.assert_service_check('kong.can_connect', status=Kong.CRITICAL, count=1)