"""Behavioral tests for the Metadata nil sentinel.

Child 1 of metadata_ssdl_defusing_20260624. Asserts:
- NIL_METADATA constant is defined in src/aggregate.py (the Metadata parent module).
- NIL_METADATA is a valid Metadata (dict[str, Any]).
- Sentinel pattern is usable: `entry or NIL_METADATA` returns a safe Metadata.
- detect_nil_check_pattern returns False for at least one migrated function in
  src/aggregate.py + src/ai_client.py (the files named in the parent campaign spec).
"""
from __future__ import annotations
import sys
from pathlib import Path

sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "scripts" / "code_path_audit"))

from code_path_audit_ssdl import detect_nil_check_pattern


def test_nil_metadata_is_defined() -> None:
 from src.aggregate import NIL_METADATA
 assert NIL_METADATA is not None, "NIL_METADATA must be a valid Metadata sentinel"
 assert isinstance(NIL_METADATA, dict), f"NIL_METADATA must be a dict (Metadata TypeAlias); got {type(NIL_METADATA)}"


def test_nil_metadata_safe_defaults() -> None:
 from src.aggregate import NIL_METADATA
 assert NIL_METADATA.get("any_missing_key") is None, "NIL_METADATA must return None for missing keys"
 assert NIL_METADATA.get("any_missing_key", "default") == "default", "NIL_METADATA must honor .get(default)"
 assert len(NIL_METADATA) >= 0, "NIL_METADATA must be a valid dict with len() support"


def test_sentinel_pattern_works() -> None:
 from src.aggregate import NIL_METADATA
 entry: dict = {}
 result = entry or NIL_METADATA
 assert result is NIL_METADATA, "empty dict should fall through to NIL_METADATA"
 entry_filled: dict = {"key": "value"}
 result2 = entry_filled or NIL_METADATA
 assert result2 is entry_filled, "filled dict should NOT be replaced by NIL_METADATA"


def test_migration_reduces_nil_check_count() -> None:
 from code_path_audit import build_pcg
 from code_path_audit_ssdl import detect_nil_check_pattern
 pcg = build_pcg("src").data
 metadata_consumers = pcg.consumers.get("Metadata", [])
 target_files = {"aggregate.py", "ai_client.py"}
 remaining = [f for f in metadata_consumers if f.file in target_files and detect_nil_check_pattern(f, "src")]
 migrated_funcs = ["_build_files_section_from_items"]
 migrated = [f for f in metadata_consumers if f.file in target_files and f.fqname.rsplit(".", 1)[-1] in migrated_funcs]
 for m in migrated:
  assert not detect_nil_check_pattern(m, "src"), f"{m.fqname} should no longer have nil-check pattern"


def test_detect_nil_check_pattern_works_for_migrated_function() -> None:
 from code_path_audit import FunctionRef
 from src.aggregate import _build_files_section_from_items
 fref = FunctionRef(fqname="src.aggregate._build_files_section_from_items", file="aggregate.py", line=300, role="consumer")
 has_nil = detect_nil_check_pattern(fref, "src")
 assert has_nil is False, (
    "_build_files_section_from_items should no longer have a nil-check pattern after sentinel migration"
)