diff --git a/virtualizarr/tests/test_xarray.py b/virtualizarr/tests/test_xarray.py
index 34e51c7b..220cc1d0 100644
--- a/virtualizarr/tests/test_xarray.py
+++ b/virtualizarr/tests/test_xarray.py
@@ -289,7 +289,23 @@ def test_combine_by_coords(self, netcdf4_files):
         )
 
         assert combined_vds.xindexes["time"].to_pandas_index().is_monotonic_increasing
+    
+    @pytest.mark.xfail(reason="Not yet implemented, see issue #18")
+    def test_combine_by_coords_keeping_manifestarrays(self, netcdf4_files):
+        filepath1, filepath2 = netcdf4_files
+
+        with pytest.warns(UserWarning, match="will create in-memory pandas indexes"):
+            vds1 = open_virtual_dataset(filepath1)
+        with pytest.warns(UserWarning, match="will create in-memory pandas indexes"):
+            vds2 = open_virtual_dataset(filepath2)
+
+        combined_vds = xr.combine_by_coords(
+            [vds2, vds1],
+        )
 
+        assert isinstance(combined_vds["time"].data, ManifestArray)
+        assert isinstance(combined_vds["lat"].data, ManifestArray)
+        assert isinstance(combined_vds["lon"].data, ManifestArray)
 
 @network
 @requires_s3fs