Add test for bounds behavior

ctapipe/io/tests/test_pointing.py

@@ -111,3 +111,44 @@ def test_hdf5(tmp_path):
         alt, az = interpolator(tel_id=1, time=t0 + 1 * u.s)
         assert u.isclose(alt, 69 * u.deg)
         assert u.isclose(az, 1 * u.deg)
+
+
+def test_bounds():
+    """Test invalid pointing tables raise nice errors"""
+    from ctapipe.io.pointing import PointingInterpolator
+
+    t0 = Time("2022-01-01T00:00:00")
+
+    table = Table(
+        {
+            "time": t0 + np.arange(0.0, 10.1, 2.0) * u.s,
+            "azimuth": np.linspace(0.0, 10.0, 6) * u.deg,
+            "altitude": np.linspace(70.0, 60.0, 6) * u.deg,
+        },
+    )
+
+    interpolator = PointingInterpolator()
+    interpolator.add_table(1, table)
+
+    with pytest.raises(ValueError, match="below the interpolation range"):
+        interpolator(tel_id=1, time=t0 - 0.1 * u.s)
+
+    with pytest.raises(ValueError, match="above the interpolation range"):
+        interpolator(tel_id=1, time=t0 + 10.2 * u.s)
+
+    interpolator = PointingInterpolator(bounds_error=False)
+    interpolator.add_table(1, table)
+    for dt in (-0.1, 10.1) * u.s:
+        alt, az = interpolator(tel_id=1, time=t0 + dt)
+        assert np.isnan(alt.value)
+        assert np.isnan(az.value)
+
+    interpolator = PointingInterpolator(bounds_error=False, extrapolate=True)
+    interpolator.add_table(1, table)
+    alt, az = interpolator(tel_id=1, time=t0 - 1 * u.s)
+    assert u.isclose(alt, 71 * u.deg)
+    assert u.isclose(az, -1 * u.deg)
+
+    alt, az = interpolator(tel_id=1, time=t0 + 11 * u.s)
+    assert u.isclose(alt, 59 * u.deg)
+    assert u.isclose(az, 11 * u.deg)