Add tests for combining config and kwargs (#182)

tests/store/test_s3.py

@@ -1,6 +1,7 @@
 import pytest
 
 import obstore as obs
+from obstore.exceptions import ObstoreError
 from obstore.store import S3Store
 
 
@@ -20,3 +21,15 @@ async def test_get_async(s3_store: S3Store):
 def test_construct_store_boolean_config():
     # Should allow boolean parameter
     S3Store("bucket", skip_signature=True)
+
+
+def test_error_overlapping_config_kwargs():
+    with pytest.raises(ObstoreError, match="Duplicate key"):
+        S3Store("bucket", config={"skip_signature": True}, skip_signature=True)
+
+    # Also raises for variations of the same parameter
+    with pytest.raises(ObstoreError, match="Duplicate key"):
+        S3Store("bucket", config={"aws_skip_signature": True}, skip_signature=True)
+
+    with pytest.raises(ObstoreError, match="Duplicate key"):
+        S3Store("bucket", config={"AWS_SKIP_SIGNATURE": True}, skip_signature=True)