Fail gracefully if cache directory is read only (#430)

brainglobe_atlasapi/bg_atlas.py

@@ -204,10 +204,14 @@ def check_latest_version(
             True if it is, and None if we are offline.
         """
 
-        if self.remote_version is None:  # in this case, we are offline
+        # Cache remote version to avoid multiple requests
+        remote_version = self.remote_version
+        # If we are offline, return None
+        if remote_version is None:
             return
+
         local = _version_str_from_tuple(self.local_version)
-        online = _version_str_from_tuple(self.remote_version)
+        online = _version_str_from_tuple(remote_version)
 
         if local != online:
             if print_warning:

brainglobe_atlasapi/utils.py

@@ -291,7 +291,7 @@ def get_download_size(url: str) -> int:
 
 
 def conf_from_url(url) -> configparser.ConfigParser:
-    """Read conf file from an URL. And cache a copy in the brainglobe dir.
+    """Read conf file from a URL. And cache a copy in the brainglobe dir.
     Parameters
     ----------
     url : str
@@ -305,14 +305,17 @@ def conf_from_url(url) -> configparser.ConfigParser:
     text = requests.get(url).text
     config_obj = configparser.ConfigParser()
     config_obj.read_string(text)
-    cache_path = config.get_brainglobe_dir() / "last_versions.conf"
+    cache_path: Path = config.get_brainglobe_dir() / "last_versions.conf"
 
-    if not cache_path.parent.exists():
-        cache_path.parent.mkdir(parents=True, exist_ok=True)
-
-    # Cache the available atlases
-    with open(cache_path, "w") as f_out:
-        config_obj.write(f_out)
+    try:
+        if not cache_path.parent.exists():
+            cache_path.parent.mkdir(parents=True, exist_ok=True)
+
+        # Cache the available atlases
+        with open(cache_path, "w") as f_out:
+            config_obj.write(f_out)
+    except OSError as e:
+        print(f"Could not update the latest atlas versions cache: {e}")
 
     return config_obj
 

tests/atlasapi/test_utils.py

@@ -1,3 +1,5 @@
+import os
+import sys
 from unittest import mock
 
 import pytest
@@ -7,6 +9,9 @@
 from brainglobe_atlasapi import utils
 
 test_url = "https://gin.g-node.org/BrainGlobe/atlases/raw/master/example_mouse_100um_v1.2.tar.gz"
+conf_url = (
+    "https://gin.g-node.org/BrainGlobe/atlases/raw/master/last_versions.conf"
+)
 
 
 def test_http_check():
@@ -138,3 +143,26 @@ def test_conf_from_file_no_file(temp_path):
         utils.conf_from_file(conf_path)
 
         assert "Last versions cache file not found." == str(e)
+
+
+@pytest.mark.skipif(sys.platform == "win32", reason="Does not run on Windows")
+def test_conf_from_url_read_only(temp_path, mocker):
+    # Test with a valid URL and a non-existing parent folder
+    mocker.patch(
+        "brainglobe_atlasapi.utils.config.get_brainglobe_dir"
+    ).return_value = temp_path
+    mock_print = mocker.patch("builtins.print")
+    # Save the current permissions
+    curr_mode = oct(os.stat(temp_path).st_mode)[-3:]
+
+    # Change the permissions to read-only
+    temp_path.chmod(0o444)
+    utils.conf_from_url(conf_url)
+
+    mock_print.assert_called_once_with(
+        f"Could not update the latest atlas versions cache: [Errno 13] "
+        f"Permission denied: '{temp_path / 'last_versions.conf'}'"
+    )
+
+    # Set the permissions back to the original
+    temp_path.chmod(int(curr_mode, 8))