gps-denied-onboard/tests/unit/test_az697_gps_compare.py

"""AZ-697 AC-5 — gps_compare helper-move snapshot.

The ``l2_horizontal_m`` / ``match_percentage`` / ``GroundTruthRow``
trio moved from ``tests/e2e/replay/_helpers.py`` into production code
at ``src/gps_denied_onboard/helpers/gps_compare.py``. This module
pins the post-move numerical behaviour so a future refactor of either
the helper or the test re-export can't silently drift.

The numerical reference values are hand-computed against the WGS84
mean Earth radius used by ``helpers/wgs_converter.py`` (AZ-279). The
``tests/e2e/replay/test_helpers.py`` module continues to import from
``tests/e2e/replay/_helpers`` (which now re-exports from the
production location), so both call sites are exercised.

Style: every test follows the Arrange / Act / Assert pattern.
"""

from __future__ import annotations

import pytest

from gps_denied_onboard.helpers.gps_compare import (
    GroundTruthRow,
    l2_horizontal_m,
    match_percentage,
)


# ---------------------------------------------------------------------
# Snapshot: production location vs prior test-helpers location


def test_l2_zero_at_same_point() -> None:
    # Act
    d = l2_horizontal_m(50.08, 36.11, 50.08, 36.11)

    # Assert
    assert d == pytest.approx(0.0, abs=1e-6)


def test_l2_one_degree_latitude_is_111km() -> None:
    # Act
    d = l2_horizontal_m(50.08, 36.11, 51.08, 36.11)

    # Assert — one degree of latitude on a sphere of radius 6_371_008.8 m.
    assert d == pytest.approx(111_195.0, rel=0.001)


def test_l2_symmetric() -> None:
    # Arrange
    a = (49.991, 36.221)
    b = (50.080, 36.111)

    # Act
    d_ab = l2_horizontal_m(*a, *b)
    d_ba = l2_horizontal_m(*b, *a)

    # Assert
    assert d_ab == pytest.approx(d_ba, rel=1e-12)


def test_l2_kharkiv_to_kyiv_known_pair() -> None:
    # Arrange — externally known reference distance is ~411 km.
    kharkiv_lat, kharkiv_lon = 49.9935, 36.2304
    kyiv_lat, kyiv_lon = 50.4501, 30.5234

    # Act
    d = l2_horizontal_m(kharkiv_lat, kharkiv_lon, kyiv_lat, kyiv_lon)

    # Assert
    assert d == pytest.approx(411_000.0, rel=0.005)


def test_match_percentage_all_within_threshold() -> None:
    # Arrange
    gt = [GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)]
    emissions = [
        {
            "emitted_at": 0,
            "position_wgs84": {"lat_deg": 50.0, "lon_deg": 36.0, "alt_m": 100.0},
        }
    ]

    # Act
    pct = match_percentage(emissions, gt, threshold_m=100.0)

    # Assert
    assert pct == 1.0


def test_match_percentage_none_within_threshold() -> None:
    # Arrange
    gt = [GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)]
    emissions = [
        {
            "emitted_at": 0,
            # ~111 km north of the GT row.
            "position_wgs84": {"lat_deg": 51.0, "lon_deg": 36.0, "alt_m": 100.0},
        }
    ]

    # Act
    pct = match_percentage(emissions, gt, threshold_m=100.0)

    # Assert
    assert pct == 0.0


def test_match_percentage_empty_emissions_zero() -> None:
    # Arrange
    gt = [GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)]

    # Act
    pct = match_percentage([], gt, threshold_m=100.0)

    # Assert
    assert pct == 0.0


def test_match_percentage_empty_ground_truth_raises() -> None:
    # Act / Assert
    with pytest.raises(AssertionError, match="ground_truth must be non-empty"):
        match_percentage(
            [{"emitted_at": 0, "position_wgs84": {"lat_deg": 50, "lon_deg": 36}}],
            [],
            threshold_m=100.0,
        )


def test_ground_truth_row_is_frozen() -> None:
    # Arrange
    row = GroundTruthRow(t_s=0.0, lat_deg=50.0, lon_deg=36.0, alt_m=100.0)

    # Act / Assert
    with pytest.raises((AttributeError, TypeError)):
        row.lat_deg = 51.0  # type: ignore[misc]


# ---------------------------------------------------------------------
# Snapshot: re-export from prior test-helpers location returns the
# same object as the production import. Guarantees there is no second
# divergent copy under tests/.


def test_test_helpers_reexport_is_identical() -> None:
    # Act
    from tests.e2e.replay import _helpers as test_helpers_module

    # Assert — identity, not just equality.
    assert test_helpers_module.l2_horizontal_m is l2_horizontal_m
    assert test_helpers_module.match_percentage is match_percentage
    assert test_helpers_module.GroundTruthRow is GroundTruthRow