Add unit test for torch_tensor_get_device_index on CPU

src/test/unit/test_tensor_interrogation.pf

@@ -19,6 +19,32 @@ module test_tensor_interrogation
 
 contains
 
+  ! Unit test for the torch_tensor_get_device_index function applied to a tensor on the CPU
+  @test
+  subroutine test_torch_tensor_get_device_index_default()
+    use ftorch, only: torch_tensor_get_device_index
+
+    implicit none
+
+    type(torch_tensor) :: tensor
+    integer, parameter :: ndims = 1
+    integer(c_int64_t), parameter, dimension(ndims) :: tensor_shape = [1]
+    integer, parameter :: dtype = torch_kFloat32
+    integer, parameter :: expected = -1
+
+    ! Create an empty tensor on the CPU with the default device index
+    call torch_tensor_empty(tensor, ndims, tensor_shape, dtype, device_type)
+
+    ! Check that torch_tensor_get_device_index can get the device index
+    if (expected /= torch_tensor_get_device_index(tensor)) then
+      call torch_tensor_delete(tensor)
+      print *, "Error :: torch_tensor_get_device_index returned incorrect CPU device index"
+      stop 999
+    end if
+    call torch_tensor_delete(tensor)
+
+  end subroutine test_torch_tensor_get_device_index_default
+
   ! Unit test for the get_rank method of a 1D tensor
   @test
   subroutine test_get_rank_1D()