Fix bug when scalar is empty returns None

Author: roaffix

arrayfire/array_api/_array_object.py

@@ -502,11 +502,13 @@ def shape(self) -> ShapeType:
             ctypes.pointer(d0), ctypes.pointer(d1), ctypes.pointer(d2), ctypes.pointer(d3), self.arr))
         return (d0.value, d1.value, d2.value, d3.value)[:self.ndim]  # Skip passing None values
 
-    def scalar(self) -> int | float | bool | complex:
+    def scalar(self) -> None | int | float | bool | complex:
         """
         Return the first element of the array
         """
-        # BUG seg fault on empty array
+        if self.is_empty():
+            return None
+
         out = self.dtype.c_type()
         safe_call(backend.get().af_get_scalar(ctypes.pointer(out), self.arr))
         return out.value  # type: ignore[no-any-return]  # FIXME

arrayfire/array_api/tests/test_array_object.py

@@ -107,10 +107,24 @@ def test_array_getitem() -> None:
     # TODO add more tests for different dtypes
 
 
+def test_scalar() -> None:
+    array = Array([1, 2, 3])
+    assert array[1].scalar() == 2
+
+
+def test_scalar_is_empty() -> None:
+    array = Array()
+    assert array.scalar() is None
+
+
 def test_array_to_list() -> None:
-    # TODO add test of to_ctypes_array
-    assert Array([1, 2, 3]).to_list() == [1, 2, 3]
-    assert Array().to_list() == []
+    array = Array([1, 2, 3])
+    assert array.to_list() == [1, 2, 3]
+
+
+def test_array_to_list_is_empty() -> None:
+    array = Array()
+    assert array.to_list() == []
 
 
 def test_array_add() -> None: