add test for copy buffer in test_io.py

python/pyarrow/tests/test_io.py

@@ -699,6 +699,13 @@ def test_non_cpu_buffer(pickle_module):
     # Sliced buffers with same address
     assert buf_on_gpu_sliced.equals(cuda_buf[2:4])
 
+    # Testing copying buffer
+    mm = ctx.memory_manager
+    buf2 = cuda_buf.copy(mm)
+    cuda_buf2 = cuda.CudaBuffer.from_buffer(buf2)
+    cuda_buf2.size == cuda_buf.size
+    cuda_buf2.copy_to_host()[:] == b'testing'
+
     # Buffers on different devices
     msg_device = "Device on which the data resides differs between buffers"
     with pytest.raises(ValueError, match=msg_device):