Handle case where input is a directory better (#433)

If a user configures a directory and not a simple file as the state
store location, the error message produced is not very easy to
understand. On windows in particular, it results in a "permission
denied" error.

This adds a more descriptive error message

Author: mathialo

cognite/extractorutils/configtools/elements.py

@@ -18,6 +18,7 @@
 from datetime import timedelta
 from enum import Enum
 from logging.handlers import TimedRotatingFileHandler
+from pathlib import Path
 from time import sleep
 from typing import Any
 from urllib.parse import urljoin, urlparse
@@ -649,7 +650,7 @@ class LocalStateStoreConfig:
     Configuration of a state store using a local JSON file
     """
 
-    path: str
+    path: Path
     save_interval: TimeIntervalConfig = TimeIntervalConfig("30s")
 
 
@@ -695,8 +696,11 @@ def create_state_store(
             )
 
         if self.local:
+            if self.local.path.is_dir():
+                raise ValueError(f"{self.local.path} is a directory, and not a file")
+
             return LocalStateStore(
-                file_path=self.local.path,
+                file_path=str(self.local.path),
                 save_interval=self.local.save_interval.seconds,
                 cancellation_token=cancellation_token,
             )

tests/tests_unit/test_configtools.py

@@ -16,11 +16,13 @@
 import logging
 import os
 import re
+from collections.abc import Generator
 from dataclasses import dataclass
 from pathlib import Path
 
 import pytest
 import yaml
+from faker import Faker
 
 from cognite.client import CogniteClient
 from cognite.client.credentials import OAuthClientCredentials
@@ -37,15 +39,18 @@
     AuthenticatorConfig,
     CastableInt,
     IgnorePattern,
+    LocalStateStoreConfig,
     PortNumber,
     RegExpFlag,
+    StateStoreConfig,
 )
 from cognite.extractorutils.configtools.loaders import (
     ConfigResolver,
     compile_patterns,
 )
 from cognite.extractorutils.configtools.validators import matches_pattern, matches_patterns
 from cognite.extractorutils.exceptions import InvalidConfigError
+from cognite.extractorutils.statestore.watermark import LocalStateStore
 
 
 @dataclass
@@ -610,3 +615,42 @@ class DbConfigCastable:
     assert parsed.port == 8080
     assert parsed.connections == 4
     assert parsed.batch_size == 1000
+
+
+@pytest.fixture
+def file_name() -> Generator[str, None, None]:
+    name = f"{Faker().word()}.json"
+    yield name
+    if Path(name).exists():
+        os.remove(name)
+
+
+def test_load_local_statestore(file_name: str) -> None:
+    raw_config = f"""
+    local:
+        path: {file_name}
+    """
+
+    config = load_yaml(raw_config, StateStoreConfig)
+
+    assert isinstance(config.local, LocalStateStoreConfig)
+    assert str(config.local.path) == file_name
+
+    state_store = config.create_state_store()
+    assert isinstance(state_store, LocalStateStore)
+
+
+def test_load_local_directory_fails() -> None:
+    raw_config = """
+    local:
+        path: cognite
+    """
+
+    config = load_yaml(raw_config, StateStoreConfig)
+
+    assert isinstance(config.local, LocalStateStoreConfig)
+
+    with pytest.raises(ValueError) as e:
+        config.create_state_store()
+
+    assert "is a directory, and not a file" in str(e.value)