(fix): no asyncio.run for clearing a store (#1933)

* (fix): no `asyncio.run` for clearing a store

* (chore): test

* (chore): relnote

Author: ilan-gold

docs/release-notes/1933.bugfix.md

@@ -0,0 +1 @@
+Don't use {func}`asyncio.run` internally for any operations {user}`ilan-gold`

src/anndata/_io/specs/registry.py

@@ -361,9 +361,9 @@ def write_elem(
 
         if k == "/":
             if isinstance(store, ZarrGroup) and not is_zarr_v2():
-                import asyncio
+                from zarr.core.sync import sync
 
-                asyncio.run(store.store.clear())
+                sync(store.store.clear())
             else:
                 store.clear()
         elif k in store:

tests/test_readwrite.py

@@ -131,6 +131,24 @@ def test_readwrite_roundtrip(typ, tmp_path, diskfmt, diskfmt2):
     assert_equal(adata2, adata1)
 
 
+def test_readwrite_roundtrip_async(tmp_path):
+    import asyncio
+
+    async def _do_test():
+        zarr_path = tmp_path / "first.zarr"
+
+        adata1 = ad.AnnData(
+            csr_matrix(X_list), obs=obs_dict, var=var_dict, uns=uns_dict
+        )
+        adata1.write_zarr(zarr_path)
+        adata2 = ad.read_zarr(zarr_path)
+
+        assert_equal(adata2, adata1)
+
+    # This test ensures our file i/o never calls `asyncio.run` internally
+    asyncio.run(_do_test())
+
+
 @pytest.mark.parametrize("storage", ["h5ad", "zarr"])
 @pytest.mark.parametrize("typ", [np.array, csr_matrix, csr_array, as_dense_dask_array])
 def test_readwrite_kitchensink(tmp_path, storage, typ, backing_h5ad, dataset_kwargs):