[DBMON-6003] Add Postgres unit tests to track all config default value changes (DataDog#22160)

* Add unit tests to track all config default value changes

* ddev format

Author: eric-weaver

postgres/tests/test_config_defaults.py

@@ -0,0 +1,358 @@
+# (C) Datadog, Inc. 2025-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+
+"""
+The goal of these tests are to verify our default configuration values are correct and remain consistent.
+Failing tests indicate a regression in our defaults and should be looked inspected carefully.
+Default values are duplicated within this file by design to ensure tests fail if the value changes unexpectedly.
+"""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+from datadog_checks.postgres.config import build_config
+
+# Single source of truth for all expected default values
+# Organized by category for readability
+EXPECTED_DEFAULTS = {
+    # === Required fields (no defaults) ===
+    'host': None,  # Required, user must provide
+    'username': None,  # Required, user must provide
+    'password': None,  # Required, user must provide (optional for managed auth)
+    # === Connection configuration ===
+    'port': 5432,
+    'dbname': 'postgres',
+    'ssl': 'allow',
+    'ssl_root_cert': None,
+    'ssl_cert': None,
+    'ssl_key': None,
+    'ssl_password': None,
+    'query_timeout': 5000,
+    'idle_connection_timeout': 60000,
+    'max_connections': 30,
+    'application_name': 'datadog-agent',
+    # === Identification ===
+    'reported_hostname': None,
+    'exclude_hostname': False,
+    'data_directory': '/usr/local/pgsql/data',
+    'database_identifier': {
+        'template': '$resolved_hostname',
+    },
+    # === Metric collection toggles ===
+    'dbstrict': False,
+    'collect_function_metrics': False,
+    'collect_count_metrics': True,
+    'collect_checksum_metrics': False,
+    'collect_activity_metrics': False,
+    'collect_buffercache_metrics': False,
+    'collect_database_size_metrics': True,
+    'collect_default_database': True,
+    'collect_bloat_metrics': False,
+    'collect_wal_metrics': True,
+    'tag_replication_role': True,
+    'table_count_limit': 200,
+    'max_relations': 300,
+    # === Database filtering ===
+    'ignore_databases': [
+        'template0',
+        'template1',
+        'rdsadmin',
+        'azure_maintenance',
+        'cloudsqladmin',
+        'alloydbadmin',
+        'alloydbmetadata',
+    ],
+    'ignore_schemas_owned_by': [
+        'rds_superuser',
+        'rdsadmin',
+    ],
+    # === Database monitoring (DBM) ===
+    'dbm': False,
+    'pg_stat_statements_view': 'pg_stat_statements',
+    'pg_stat_activity_view': 'pg_stat_activity',
+    'log_unobfuscated_queries': False,
+    'log_unobfuscated_plans': False,
+    'database_instance_collection_interval': 300,
+    # === DBM: Query metrics ===
+    'query_metrics': {
+        'enabled': True,
+        'collection_interval': 10,
+        'pg_stat_statements_max_warning_threshold': 10000,
+        'incremental_query_metrics': False,
+        'baseline_metrics_expiry': 300,
+        'full_statement_text_cache_max_size': 10000,
+        'full_statement_text_samples_per_hour_per_query': 1,
+        'run_sync': False,
+    },
+    # === DBM: Query samples ===
+    'query_samples': {
+        'enabled': True,
+        'collection_interval': 1,
+        'explain_function': 'datadog.explain_statement',
+        'explained_queries_per_hour_per_query': 60,
+        'samples_per_hour_per_query': 15,
+        'explained_queries_cache_maxsize': 5000,
+        'seen_samples_cache_maxsize': 10000,
+        'explain_parameterized_queries': True,
+        'explain_errors_cache_maxsize': 5000,
+        'explain_errors_cache_ttl': 86400,
+        'run_sync': False,
+    },
+    # === DBM: Query activity ===
+    'query_activity': {
+        'enabled': True,
+        'collection_interval': 10,
+        'payload_row_limit': 3500,
+    },
+    # === DBM: Settings collection ===
+    'collect_settings': {
+        'enabled': True,
+        'collection_interval': 600,
+        'run_sync': False,
+        'ignored_settings_patterns': ['plpgsql%'],
+    },
+    # === DBM: Schema collection ===
+    'collect_schemas': {
+        'enabled': False,
+        'max_tables': 300,
+        'max_columns': 50,
+        'collection_interval': 600,
+        'max_query_duration': 60,
+    },
+    # === DBM: Obfuscator options ===
+    'obfuscator_options': {
+        'obfuscation_mode': 'obfuscate_and_normalize',
+        'replace_digits': False,
+        'collect_metadata': True,
+        'collect_tables': True,
+        'collect_commands': True,
+        'collect_comments': True,
+        'keep_sql_alias': True,
+        'keep_dollar_quoted_func': True,
+        'remove_space_between_parentheses': False,
+        'keep_null': False,
+        'keep_boolean': False,
+        'keep_positional_parameter': False,
+        'keep_trailing_semicolon': False,
+        'keep_identifier_quotation': False,
+        'keep_json_path': False,
+    },
+    # === DBM: Database autodiscovery ===
+    'database_autodiscovery': {
+        'enabled': False,
+        'global_view_db': 'postgres',
+        'max_databases': 100,
+        'refresh': 600,
+        'exclude': ['cloudsqladmin', 'rdsadmin', 'alloydbadmin', 'alloydbmetadata'],
+        'include': ['.*'],
+    },
+    # === DBM: Lock metrics ===
+    'locks_idle_in_transaction': {
+        'enabled': True,
+        'collection_interval': 300,
+        'max_rows': 100,
+    },
+    # === DBM: Raw query statements ===
+    'collect_raw_query_statement': {
+        'enabled': False,
+    },
+    # === Relations configuration ===
+    'relations': [],
+    # === Query encodings ===
+    'query_encodings': ['utf8'],
+    # === Activity metrics ===
+    'activity_metrics_excluded_aggregations': [],
+    # === Cloud provider configurations ===
+    'aws': {
+        'instance_endpoint': None,
+        'region': None,
+        'managed_authentication': {'enabled': None},
+    },
+    'azure': {
+        'deployment_type': None,
+        'fully_qualified_domain_name': None,
+        'managed_authentication': {'enabled': None},
+    },
+    'gcp': {
+        'project_id': None,
+        'instance_id': None,
+    },
+    # === Tagging ===
+    'tags': ('server:localhost', 'port:5432', 'db:postgres'),  # Dynamically generated from connection info
+    'disable_generic_tags': False,
+    'propagate_agent_tags': False,
+    # === Custom metrics/queries (deprecated/user-provided) ===
+    'custom_metrics': (),  # Deprecated field, defaults to empty tuple
+    'custom_queries': (),  # User-provided queries, defaults to empty tuple
+    'only_custom_queries': False,  # Flag to run only custom queries
+    'use_global_custom_queries': 'true',  # Use custom queries from init_config
+    'service': None,  # User-provided service name
+    'metric_patterns': None,  # User-provided patterns
+    # === Agent standard fields ===
+    'min_collection_interval': 15.0,  # Standard Agent field
+    'empty_default_hostname': False,  # Deprecated field
+}
+
+
+@pytest.fixture
+def mock_check():
+    """Mock check object with a warning method."""
+    check = MagicMock()
+    check.warning = MagicMock()
+    return check
+
+
+@pytest.fixture
+def minimal_instance():
+    """Minimal instance configuration with only required fields."""
+    return {
+        'host': 'localhost',
+        'username': 'testuser',
+        'password': 'testpass',
+    }
+
+
+pytestmark = pytest.mark.unit
+
+
+def test_all_config_defaults(mock_check, minimal_instance):
+    """
+    Verify that all InstanceConfig fields have the expected default values.
+
+    This test iterates through every field in InstanceConfig and validates its default.
+    If a field is missing from EXPECTED_DEFAULTS, the test will fail with instructions.
+    """
+    from datadog_checks.postgres.config_models.instance import InstanceConfig
+
+    # Build config with minimal instance
+    mock_check.instance = minimal_instance
+    mock_check.init_config = {}
+    config, result = build_config(check=mock_check)
+
+    # Get all fields from InstanceConfig
+    all_fields = set(InstanceConfig.__annotations__.keys())
+
+    # Check for fields in InstanceConfig that aren't in EXPECTED_DEFAULTS
+    missing_from_expected = all_fields - set(EXPECTED_DEFAULTS.keys())
+    if missing_from_expected:
+        error_msg = (
+            f"\n\n{'=' * 80}\n"
+            f"MISSING EXPECTED DEFAULTS!\n"
+            f"{'=' * 80}\n\n"
+            f"The following fields exist in InstanceConfig but are missing from EXPECTED_DEFAULTS:\n"
+            f"  {sorted(missing_from_expected)}\n\n"
+            f"To fix this:\n"
+            f"Add each field to the EXPECTED_DEFAULTS dictionary in test_config_defaults.py\n"
+            f"with its expected default value.\n\n"
+            f"Examples:\n"
+            f"  - Simple field: 'field_name': default_value,\n"
+            f"  - No default (user-provided): 'field_name': None,\n"
+            f"  - Nested object: 'field_name': {{'key': 'value'}},\n"
+            f"  - Array: 'field_name': ['item1', 'item2'],\n\n"
+            f"{'=' * 80}\n"
+        )
+        pytest.fail(error_msg)
+
+    # Check for fields in EXPECTED_DEFAULTS that aren't in InstanceConfig (cleanup needed)
+    extra_in_expected = set(EXPECTED_DEFAULTS.keys()) - all_fields
+    if extra_in_expected:
+        pytest.fail(
+            f"\n\nThe following fields are in EXPECTED_DEFAULTS but don't exist in InstanceConfig:\n"
+            f"  {sorted(extra_in_expected)}\n"
+            f"These should be removed from EXPECTED_DEFAULTS."
+        )
+
+    # Required fields that come from minimal_instance - skip validation since they're user-provided
+    SKIP_VALIDATION = {'host', 'username', 'password'}
+
+    # Now validate each field's actual default against expected
+    failures = []
+
+    for field_name, expected_value in EXPECTED_DEFAULTS.items():
+        if field_name in SKIP_VALIDATION:
+            continue
+
+        try:
+            actual_value = getattr(config, field_name)
+        except AttributeError:
+            failures.append(f"{field_name}: Field not accessible on config object")
+            continue
+
+        # Handle different types of comparisons
+        if isinstance(expected_value, dict):
+            # For nested objects, recursively check fields
+            if not _compare_nested_object(actual_value, expected_value, field_name, failures):
+                continue
+        elif isinstance(expected_value, (list, tuple)):
+            # Convert actual value to same type for comparison
+            if isinstance(actual_value, (list, tuple)):
+                actual_as_type = type(expected_value)(actual_value)
+                if actual_as_type != expected_value:
+                    failures.append(f"{field_name}: expected {expected_value!r}, got {actual_value!r}")
+            elif actual_value is None:
+                failures.append(f"{field_name}: expected {expected_value!r}, got None")
+            else:
+                failures.append(f"{field_name}: expected {expected_value!r}, got {actual_value!r}")
+        else:
+            # Simple value comparison
+            if actual_value != expected_value:
+                failures.append(f"{field_name}: expected {expected_value!r}, got {actual_value!r}")
+
+    if failures:
+        error_msg = (
+            f"\n\n{'=' * 80}\n"
+            f"DEFAULT VALUE MISMATCHES DETECTED!\n"
+            f"{'=' * 80}\n\n"
+            f"The following fields have default values that don't match expectations:\n\n"
+            + "\n".join(f"  • {failure}" for failure in failures)
+            + f"\n\n"
+            f"This indicates either:\n"
+            f"  1. A regression in default values (BAD - investigate carefully!)\n"
+            f"  2. EXPECTED_DEFAULTS needs to be updated to match new behavior\n\n"
+            f"{'=' * 80}\n"
+        )
+        pytest.fail(error_msg)
+
+
+def _compare_nested_object(actual_obj, expected_dict, field_path, failures):
+    """
+    Recursively compare a nested config object against expected dictionary.
+
+    Returns True if all comparisons passed, False if any failed (failures list is updated).
+    """
+    all_passed = True
+
+    for key, expected_value in expected_dict.items():
+        try:
+            actual_value = getattr(actual_obj, key)
+        except AttributeError:
+            failures.append(f"{field_path}.{key}: Field not accessible")
+            all_passed = False
+            continue
+
+        if isinstance(expected_value, dict):
+            # Recursively check nested objects
+            if not _compare_nested_object(actual_value, expected_value, f"{field_path}.{key}", failures):
+                all_passed = False
+        elif isinstance(expected_value, (list, tuple)):
+            # Convert actual value to same type for comparison
+            if isinstance(actual_value, (list, tuple)):
+                actual_as_type = type(expected_value)(actual_value)
+                if actual_as_type != expected_value:
+                    failures.append(f"{field_path}.{key}: expected {expected_value!r}, got {actual_value!r}")
+                    all_passed = False
+            elif actual_value is None:
+                failures.append(f"{field_path}.{key}: expected {expected_value!r}, got None")
+                all_passed = False
+            else:
+                failures.append(f"{field_path}.{key}: expected {expected_value!r}, got {actual_value!r}")
+                all_passed = False
+        else:
+            # Simple value comparison
+            if actual_value != expected_value:
+                failures.append(f"{field_path}.{key}: expected {expected_value!r}, got {actual_value!r}")
+                all_passed = False
+
+    return all_passed