[cppyy] lowlevel view unittest for multidim fixed-length array to numpy

Author: aaronj0

bindings/pyroot/cppyy/cppyy/test/test_lowlevel.py

@@ -742,6 +742,42 @@ def test05_char_multidim(self):
         for i, v in enumerate(("s1", "s23", "s456")):
             assert len(ns.str_array[i]) == 7
             assert ns.str_array[i].as_string() == v
+    
+    def test06_fixed_multidim_array_itemsize(self):
+        """conversion of fixed-length array low level views into NumPy arrays"""
+        import cppyy
+        try:
+            import numpy as np
+        except ImportError:
+            skip('numpy is not installed')
+
+        cases = [
+            ('float',          np.float32,  (3, 5)),
+            ('int',            np.intc,     (2, 6)),
+            ('short',          np.short,    (5, 3)),
+            ('unsigned char',  np.ubyte,    (4, 4)),
+            ('int32_t',        np.int32,    (2, 8)),
+            ('uint16_t',       np.uint16,   (7, 3)),
+        ]
+
+        for cpp_type, np_dtype, (rows, cols) in cases:
+            tag = cpp_type.replace(' ', '_')
+            cppyy.cppdef(f"""
+                struct LLVFixed2D_{tag} {{
+                    {cpp_type} a[{rows}][{cols}];
+                }};
+            """)
+            s = getattr(cppyy.gbl, f'LLVFixed2D_{tag}')()
+
+            itemsize = np.dtype(np_dtype).itemsize
+            mv = memoryview(s.a)
+            assert mv.ndim     == 2
+            assert mv.shape    == (rows, cols)
+            assert mv.itemsize == itemsize
+            assert mv.strides  == (cols * itemsize, itemsize)
+
+            arr = np.array(s.a, dtype=np_dtype)
+            assert arr.shape == (rows, cols)
 
 
 if __name__ == "__main__":