Initial Vibe coded project

tests/test_curves.py

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+import math
+import random
+
+import pytest
+
+from flight_map.curves import Cubic, interpolate
+
+
+def test_spline_interpolates_samples_with_continuous_tangent() -> None:
+    points = [(0.0, 0.0), (1.0, 2.0), (5.0, 3.0), (6.0, -1.0)]
+    curves = interpolate(points)
+    assert len(curves) == len(points) - 1
+    for index, curve in enumerate(curves):
+        assert curve.point(0) == pytest.approx(points[index])
+        assert curve.point(1) == pytest.approx(points[index + 1])
+    for first, second in zip(curves, curves[1:], strict=False):
+        incoming = (first.end[0] - first.control2[0], first.end[1] - first.control2[1])
+        outgoing = (second.control1[0] - second.start[0], second.control1[1] - second.start[1])
+        cross = incoming[0] * outgoing[1] - incoming[1] * outgoing[0]
+        dot = incoming[0] * outgoing[0] + incoming[1] * outgoing[1]
+        assert abs(cross) < 1e-10 and dot > 0
+    # A non-collinear path must actually curve, not just encode straight lines as cubics.
+    assert curves[0].point(0.5) != pytest.approx((0.5, 1.0))
+
+
+def test_two_points_remain_a_straight_path_and_duplicates_are_finite() -> None:
+    curve = interpolate([(0, 0), (9, 6)])[0]
+    assert curve.point(0.5) == pytest.approx((4.5, 3))
+    for segment in interpolate([(0, 0), (0, 0), (1, 2), (1, 2), (3, 0)]):
+        assert all(math.isfinite(coordinate) for p in segment.points for coordinate in p)
+    assert interpolate([]) == []
+    assert interpolate([(0, 0)]) == []
+
+
+def test_curve_portion_preserves_original_shape() -> None:
+    curve = Cubic((-2, 0), (1, 5), (3, -5), (6, 0))
+    portion = curve.portion(0.2, 0.8)
+    for fraction in (0, 0.1, 0.5, 0.8, 1):
+        assert portion.point(fraction) == pytest.approx(curve.point(0.2 + fraction * 0.6))
+    with pytest.raises(ValueError):
+        curve.portion(0.8, 0.2)
+
+
+def test_curve_can_enter_bounds_when_both_endpoints_are_outside() -> None:
+    curve = Cubic((-2, 0), (-1, 3), (1, 3), (2, 0))
+    rectangle = (-1.0, 1.0, 1.0, 3.0)
+    portions = curve.clipped(rectangle)
+    assert len(portions) == 1
+    assert portions[0].start[0] == pytest.approx(-1)
+    assert portions[0].end[0] == pytest.approx(1)
+    assert portions[0].point(0.5)[1] > 2
+
+
+def test_clipping_handles_multiple_entries_tangency_and_boundary_lines() -> None:
+    curve = Cubic((-2, 0), (4, 0), (-4, 0), (2, 0))
+    rectangle = (-0.1, -1.0, 0.1, 1.0)
+    assert len(curve.inside_intervals(rectangle)) == 3
+    boundary = Cubic((-2, 0), (-1, 0), (1, 0), (2, 0))
+    assert len(boundary.clipped((-1, 0, 1, 1))) == 1
+    # Only touches the lower edge; it has no visible interval inside the rectangle.
+    tangent = Cubic((0, -3), (1, 1), (2, 1), (3, -3))
+    assert tangent.clipped((-1, 0, 4, 4)) == []
+
+
+def test_random_clipping_matches_dense_curve_membership() -> None:
+    randomizer = random.Random(42)
+    rectangle = (-1.0, -1.0, 1.0, 1.0)
+    for _ in range(100):
+        points = [(randomizer.uniform(-3, 3), randomizer.uniform(-3, 3)) for _ in range(4)]
+        curve = Cubic(*points)
+        intervals = curve.inside_intervals(rectangle)
+        for index in range(201):
+            t = index / 200
+            x, y = curve.point(t)
+            inside = -1 <= x <= 1 and -1 <= y <= 1
+            selected = any(first - 1e-10 <= t <= last + 1e-10 for first, last in intervals)
+            assert selected == inside
+        for portion in curve.clipped(rectangle):
+            for index in range(51):
+                x, y = portion.point(index / 50)
+                assert -1 - 1e-8 <= x <= 1 + 1e-8 and -1 - 1e-8 <= y <= 1 + 1e-8
+
+
+def test_transformation_preserves_bezier_shape() -> None:
+    curve = Cubic((0, 0), (1, 2), (2, -1), (3, 0))
+    transformed = curve.transform([2, 0, 0, -2, 10, 20])
+    for t in (0, 0.1, 0.6, 1):
+        x, y = curve.point(t)
+        assert transformed.point(t) == pytest.approx((2 * x + 10, -2 * y + 20))