"""Tests for src/startup_profiler.py.

TDD Red phase: this file should fail before src/startup_profiler.py exists,
pass after it's implemented.
"""

import time
from pathlib import Path
import sys

ROOT = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(ROOT))

from src.startup_profiler import StartupProfiler  # noqa: E402


def test_startup_profiler_records_phase_duration() -> None:
 prof = StartupProfiler()
 with prof.phase("init_config"):
  time.sleep(0.01)
 snap = prof.snapshot()
 assert "phases" in snap
 assert "init_config" in snap["phases"]
 entry = snap["phases"]["init_config"]
 assert entry["duration_ms"] >= 8.0
 assert entry["duration_ms"] < 500.0
 assert entry["start_ts"] > 0


def test_startup_profiler_total_reflects_sum() -> None:
 prof = StartupProfiler()
 with prof.phase("a"):
  time.sleep(0.005)
 with prof.phase("b"):
  time.sleep(0.005)
 snap = prof.snapshot()
 assert snap["total_ms"] >= 10.0
 assert abs(snap["total_ms"] - (snap["phases"]["a"]["duration_ms"] + snap["phases"]["b"]["duration_ms"])) < 0.5


def test_startup_profiler_snapshot_is_independent_copy() -> None:
 prof = StartupProfiler()
 with prof.phase("x"):
  pass
 snap1 = prof.snapshot()
 with prof.phase("y"):
  pass
 snap2 = prof.snapshot()
 assert "x" in snap1["phases"]
 assert "y" not in snap1["phases"]
 assert "y" in snap2["phases"]


def test_startup_profiler_phase_records_on_exception() -> None:
 prof = StartupProfiler()
 try:
  with prof.phase("will_fail"):
   raise RuntimeError("boom")
 except RuntimeError:
  pass
 snap = prof.snapshot()
 assert "will_fail" in snap["phases"]
 assert snap["phases"]["will_fail"]["duration_ms"] >= 0


def test_startup_profiler_empty_snapshot() -> None:
 prof = StartupProfiler()
 snap = prof.snapshot()
 assert snap["phases"] == {}
 assert snap["total_ms"] == 0.0