# xarray.testing.assert_isomorphic

### xarray.testing.assert_isomorphic(a, b)[[source]](https://github.com/pydata/xarray/blob/main/xarray/testing/assertions.py#L55-L85)

Two DataTrees are considered isomorphic if the set of paths to their
descendent nodes are the same.

Nothing about the data or attrs in each node is checked.

Isomorphism is a necessary condition for two trees to be used in a nodewise binary operation,
such as tree1 + tree2.

* **Parameters:**
  * **a** ([`DataTree`](xarray.DataTree.html.md#xarray.DataTree)) – The first object to compare.
  * **b** ([`DataTree`](xarray.DataTree.html.md#xarray.DataTree)) – The second object to compare.

#### SEE ALSO
`DataTree.isomorphic`, [`assert_equal`](xarray.testing.assert_equal.html.md#xarray.testing.assert_equal), [`assert_identical`](xarray.testing.assert_identical.html.md#xarray.testing.assert_identical)