Fix and test handling of nested settings

Author: sd2k

src/mcp_grafana/settings.py

@@ -13,7 +13,7 @@ class ToolSettings(BaseSettings):
 
 class GrafanaSettings(BaseSettings):
     model_config: SettingsConfigDict = SettingsConfigDict(
-        env_prefix="GRAFANA_", env_file=".env"
+        env_prefix="GRAFANA_", env_file=".env", env_nested_delimiter="__"
     )
 
     url: str = "http://localhost:3000"

tests/settings_test.py

@@ -1,3 +1,6 @@
+import os
+from unittest.mock import patch
+
 from mcp_grafana.settings import GrafanaSettings
 
 
@@ -7,3 +10,21 @@ def test_settings():
     assert settings.api_key is None
     assert settings.tools.search.enabled
     assert settings.tools.search.limit == 1000
+
+
+@patch.dict(
+    os.environ,
+    {
+        "GRAFANA_URL": "http://localhost:3001",
+        "GRAFANA_API_KEY": "my-api-key",
+        "GRAFANA_TOOLS__SEARCH__ENABLED": "false",
+        "GRAFANA_TOOLS__SEARCH__LIMIT": "100",
+    },
+)
+def test_settings_from_env():
+    # Test we can instantiate settings from environment variables with delimiters.
+    settings = GrafanaSettings()
+    assert settings.url == "http://localhost:3001"
+    assert settings.api_key == "my-api-key"
+    assert not settings.tools.search.enabled
+    assert settings.tools.search.limit == 100