40 lines
1,010 B
Python
40 lines
1,010 B
Python
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"""Injectable clock abstraction for testability."""
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from __future__ import annotations
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from datetime import UTC, datetime, timedelta
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from typing import Protocol
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class Clock(Protocol):
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"""Clock protocol — provides current UTC time."""
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def now(self) -> datetime: ...
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class SystemClock:
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"""Real wall-clock implementation."""
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def now(self) -> datetime:
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"""Return the current UTC time."""
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return datetime.now(UTC)
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class FakeClock:
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"""Deterministic clock for tests."""
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def __init__(self, start: datetime | None = None) -> None:
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self._now = start or datetime(2026, 1, 1, tzinfo=UTC)
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def now(self) -> datetime:
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"""Return the fixed current time."""
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return self._now
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def advance(self, seconds: float) -> None:
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"""Advance the clock by the given number of seconds."""
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self._now += timedelta(seconds=seconds)
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def set(self, dt: datetime) -> None:
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"""Set the clock to an exact time."""
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self._now = dt
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