Add missing parameter to simple tiled server docstring, fix type hint, allow for both lists and strings, add unit test for readable storage

CHANGELOG.md

@@ -13,11 +13,20 @@ Write the date in place of the "Unreleased" in the case a new version is release
 - Tests and examples that use example config files; specifically an external
   NeXus file used as an example of the structure is generated dynamically at
   test time now.
+- Type hint for `readable_storage` parameter for `SimpleTiledServer` indicated it
+  should be a string or `Path`, but it actually was required to be a list of strings
+  or list of `Paths`. This has been fixed.
+- Missing docstring for `readable_storage` parameter added.
 
 ### Changed
 
 - The `start_in_thread` method of `Subscription` now waits until the WebSocket
   connection is established before returning.
+- Allow for passing a single string or `Path` to `SimpleTiledServer`'s `readable_storage`
+  parameter. Generally, when using `SimpleTiledServer` one usually just passes `/tmp` or
+  `tmp_path` in unit tests.
+- Unit test that confirms that the `readable_storage` setting works as expected, with
+  it being passed as a string, `Path`, list of strings, or list of `Path`s.
 
 ## v0.2.7 (2026-02-27)
 

tests/test_simple_server.py

@@ -1,3 +1,5 @@
+import asyncio
+import itertools
 import platform
 from pathlib import Path
 
@@ -6,6 +8,7 @@
 import pytest
 
 from tiled.client import SERVERS, from_uri, simple
+from tiled.client.register import register
 from tiled.server import SimpleTiledServer
 
 
@@ -64,6 +67,32 @@ def test_persistent_data(tmp_path):
     assert server1.directory == server2.directory == tmp_path
 
 
+@pytest.mark.parametrize(
+    ("as_list", "as_path"), list(itertools.product([True, False], [True, False]))
+)
+def test_readable_storage(tmp_path, as_list, as_path):
+    "Run server with a user-specified readable storage location."
+    readable_storage = [tmp_path / "readable"] if as_list else tmp_path / "readable"
+    if as_path:
+        readable_storage = (
+            [Path(p) for p in readable_storage]
+            if isinstance(readable_storage, list)
+            else Path(readable_storage)
+        )
+    with SimpleTiledServer(
+        directory=tmp_path / "default", readable_storage=readable_storage
+    ) as server:
+        client = from_uri(server.uri)
+        (tmp_path / "readable").mkdir(parents=True, exist_ok=True)
+        import h5py
+        import numpy
+
+        with h5py.File(tmp_path / "readable" / "data.h5", "w") as f:
+            f["x"] = numpy.array([1, 2, 3])
+        asyncio.run(register(client, tmp_path / "readable"))
+        assert (client["data"]["x"].read() == [1, 2, 3]).all()
+
+
 def test_cleanup(tmp_path):
     if platform.system() == "Windows":
         # Windows cannot delete the logfiles because the global Python

tiled/server/simple.py

@@ -58,6 +58,9 @@ class SimpleTiledServer:
     port : Optional[int]
         Port the server will listen on. By default, a random free high port
         is allocated by the operating system.
+    readable_storage : Optional[Union[str, pathlib.Path, list[str], list[pathlib.Path]]]
+        If provided, the server will be able to read from these storage locations, in addition
+        to the default storage location defined by `directory`.
 
     Examples
     --------
@@ -83,7 +86,9 @@ def __init__(
         directory: Optional[Union[str, pathlib.Path]] = None,
         api_key: Optional[str] = None,
         port: int = 0,
-        readable_storage: Optional[Union[str, pathlib.Path]] = None,
+        readable_storage: Optional[
+            Union[str, pathlib.Path, list[str], list[pathlib.Path]]
+        ] = None,
     ):
         # Delay import to avoid circular import.
         from ..catalog import from_uri as catalog_from_uri
@@ -116,6 +121,11 @@ def __init__(
         del log_config["handlers"]["default"]["stream"]
         log_config["handlers"]["default"]["filename"] = str(directory / "error.log")
 
+        # Catalog from uri wants readable storage to be a list,
+        # but we want to allow users to pass in a single path for convenience.
+        if readable_storage is not None and not isinstance(readable_storage, list):
+            readable_storage = [readable_storage]
+
         self.catalog = catalog_from_uri(
             directory / "catalog.db",
             writable_storage=[directory / "data", storage_uri],