add test for s=None vs equivalent s

Author: chillenb

mkl_fft/tests/test_fftnd.py

@@ -265,6 +265,30 @@ def test_s_axes_out(dtype, s, axes, func):
     assert_allclose(r1, r2, rtol=rtol, atol=atol)
 
 
+@requires_numpy_2
+@pytest.mark.parametrize("dtype", [complex, float])
+@pytest.mark.parametrize("axes", [(0, 1, 2), (-1, -2, -3), [1, 0, 2]])
+@pytest.mark.parametrize("func", ["fftn", "ifftn", "rfftn"])
+def test_s_none_vs_s_full(dtype, axes, func):
+    shape = (30, 20, 10)
+    if dtype is complex and func != "rfftn":
+        x = np.random.random(shape) + 1j * np.random.random(shape)
+    else:
+        x = np.random.random(shape)
+
+    implied_s = [shape[ax] for ax in axes]
+    if func == "irfftn":
+        implied_s[-1] = 2 * (implied_s[-1] - 1)
+
+    r1 = getattr(np.fft, func)(x, axes=axes)
+    r2 = getattr(mkl_fft, func)(x, axes=axes)
+    r3 = getattr(mkl_fft, func)(x, s=implied_s, axes=axes)
+
+    rtol, atol = _get_rtol_atol(x)
+    assert_allclose(r1, r2, rtol=rtol, atol=atol)
+    assert_allclose(r1, r3, rtol=rtol, atol=atol)
+
+
 @pytest.mark.parametrize("dtype", [complex, float])
 @pytest.mark.parametrize("axes", [(2, 0, 2, 0), (0, 1, 1), (2, 0, 1, 3, 2, 1)])
 @pytest.mark.parametrize("func", ["rfftn", "irfftn"])