Add unit test for shift_inversion_dask module

tests/test_shift_inversion_dask.py

+"""Unit tests for module shift_inversion_dask"""
+
+import numpy as np
+import pytest
+
+from lisainstrument.shift_inversion_numpy import make_shift_inverse_lagrange_numpy
+from lisainstrument.shift_inversion_dask import make_shift_inverse_lagrange_dask
+from lisainstrument.dynamic_delay_dask import numpyfy_dask_multi
+
+
+def test_shift_inversion_numpy():
+    """Test basic functioning of shift_inversion_dask on analytic coordinate transform"""
+    order = 31
+    nsamp = 600
+    chunks = 70
+    k_mod = 8 * np.pi
+    a_mod = 1e-3
+    max_it = 6
+    tol = 1e-12
+
+    def dx_from_x(x):
+        return np.sin(x * k_mod) * a_mod
+
+    xi, dt = np.linspace(0, 1, nsamp, retstep=True)
+    fsample = 1 / dt
+    dxi = dx_from_x(xi)
+
+    op_np = make_shift_inverse_lagrange_numpy(order, a_mod * 1.01, max_it, tol / dt)
+    op_da = make_shift_inverse_lagrange_dask(order, a_mod * 1.01, max_it, tol / dt)
+    op_na = numpyfy_dask_multi(op_da, chunks)
+
+    ai_np = op_np(dxi, fsample)
+    ai_na = op_na(dxi, fsample)
+
+    assert ai_np == pytest.approx(ai_na, abs=tol, rel=0)