utils/crdt-sync/crdt_sync/tests/test_hlc.py
Krzysztof Rudnicki 1c49abe8c2 Initial implementation: unified CRDT merge scheme + GitHub sync transport
Extracted and generalized from diet_guard's existing tombstone-merge scheme
and GitHub Contents API client, extended with per-field HLC LWW so the same
library can also cover todo's mutable notes and wake_alarm's single-value
sync (Workstream D scoping decision, 2026-07-04). 100% branch coverage,
clean ruff/mypy/pylint/bandit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017McuA1nAi6jBT1EaS5BrVf
2026-07-05 20:40:09 +02:00

101 lines
3.6 KiB
Python

"""Tests for the Hybrid Logical Clock."""
from __future__ import annotations
from typing import TYPE_CHECKING
import pytest
from crdt_sync import Hlc
if TYPE_CHECKING:
from collections.abc import Callable
class TestOrdering:
def test_greater_wall_time_wins(self, make_hlc: Callable[..., Hlc]) -> None:
assert make_hlc(200) > make_hlc(100)
def test_equal_wall_time_greater_counter_wins(
self, make_hlc: Callable[..., Hlc]
) -> None:
assert make_hlc(100, counter=2) > make_hlc(100, counter=1)
def test_equal_wall_time_and_counter_breaks_tie_on_node_id(
self, make_hlc: Callable[..., Hlc]
) -> None:
assert make_hlc(100, counter=1, node_id="b") > make_hlc(
100, counter=1, node_id="a"
)
def test_identical_clocks_compare_equal(self, make_hlc: Callable[..., Hlc]) -> None:
assert make_hlc(100, counter=1, node_id="a") == make_hlc(
100, counter=1, node_id="a"
)
class TestNewTick:
def test_first_tick_has_counter_zero(self) -> None:
tick = Hlc.new_tick("node-a", wall_time_ms=1000)
assert tick == Hlc(wall_time_ms=1000, counter=0, node_id="node-a")
def test_advancing_wall_clock_resets_counter(
self, make_hlc: Callable[..., Hlc]
) -> None:
previous = make_hlc(1000, counter=5)
tick = Hlc.new_tick("node-a", previous=previous, wall_time_ms=2000)
assert tick == Hlc(wall_time_ms=2000, counter=0, node_id="node-a")
def test_stalled_wall_clock_increments_counter(
self, make_hlc: Callable[..., Hlc]
) -> None:
previous = make_hlc(1000, counter=5)
tick = Hlc.new_tick("node-a", previous=previous, wall_time_ms=1000)
assert tick == Hlc(wall_time_ms=1000, counter=6, node_id="node-a")
def test_regressed_wall_clock_still_advances_monotonically(
self, make_hlc: Callable[..., Hlc]
) -> None:
previous = make_hlc(1000, counter=5)
tick = Hlc.new_tick("node-a", previous=previous, wall_time_ms=500)
assert tick == Hlc(wall_time_ms=1000, counter=6, node_id="node-a")
def test_defaults_to_the_real_clock_when_unset(self) -> None:
tick = Hlc.new_tick("node-a")
assert tick.node_id == "node-a"
assert tick.wall_time_ms > 0
class TestStringRoundTrip:
def test_round_trips_through_to_str_and_from_str(
self, make_hlc: Callable[..., Hlc]
) -> None:
original = make_hlc(1_751_000_123_456, counter=7, node_id="phone")
assert Hlc.from_str(original.to_str()) == original
def test_to_str_is_lexicographically_sortable_by_wall_time(
self, make_hlc: Callable[..., Hlc]
) -> None:
earlier = make_hlc(1000)
later = make_hlc(2000)
assert earlier.to_str() < later.to_str()
def test_to_str_is_lexicographically_sortable_by_counter(
self, make_hlc: Callable[..., Hlc]
) -> None:
lower = make_hlc(1000, counter=1)
higher = make_hlc(1000, counter=200)
assert lower.to_str() < higher.to_str()
def test_from_str_rejects_a_missing_z_separator(self) -> None:
with pytest.raises(ValueError, match="not a valid Hlc string"):
Hlc.from_str("not-a-valid-clock-string-at-all")
def test_from_str_rejects_a_wrong_length_iso_prefix(self) -> None:
with pytest.raises(ValueError, match="not a valid Hlc string"):
Hlc.from_str("2026-07-05T12:00:00Z-0000-node-a")
def test_from_str_rejects_a_missing_node_id_separator(self) -> None:
with pytest.raises(ValueError, match="not a valid Hlc string"):
Hlc.from_str("2026-07-05T12:00:00.000Z-0000")