added support for subtracting pedestal from np.array

python/tests/test_Pedestal.py

@@ -0,0 +1,40 @@
+import numpy as np
+import pytest
+
+from aare import Pedestal_d, Pedestal_f
+
+
+@pytest.mark.parametrize(
+    ("pedestal_type", "expected_dtype"),
+    [(Pedestal_d, np.float64), (Pedestal_f, np.float32)],
+)
+def test_numpy_array_minus_pedestal(pedestal_type, expected_dtype):
+    pedestal = pedestal_type(2, 3)
+    pedestal.push(np.array([[2, 4, 6], [8, 10, 12]], dtype=np.uint16))
+    array = np.array([[12, 14, 16], [18, 20, 22]], dtype=np.uint16)
+
+    result = array - pedestal
+
+    np.testing.assert_array_equal(
+        result, np.array([[10, 10, 10], [10, 10, 10]], dtype=expected_dtype)
+    )
+    assert result.dtype == expected_dtype
+
+
+def test_numpy_array_minus_pedestal_rejects_incompatible_shape():
+    pedestal = Pedestal_d(2, 3)
+    array = np.zeros((2, 2), dtype=np.float64)
+
+    with pytest.raises(ValueError):
+        array - pedestal
+
+
+def test_pedestal_exposes_mean_as_read_only_buffer():
+    pedestal = Pedestal_d(2, 3)
+    pedestal.push(np.array([[2, 4, 6], [8, 10, 12]], dtype=np.uint16))
+
+    mean = np.asarray(pedestal)
+
+    np.testing.assert_array_equal(mean, pedestal.view())
+    assert np.shares_memory(mean, pedestal.view())
+    assert not mean.flags.writeable