Merge pull request optuna#5565 from nabenabe0928/enhance/add-import-c…

…heck-to-artifact-store-objects

Add import check for artifact store objects

optuna/artifacts/_boto3.py

@@ -13,7 +13,7 @@
 
     from mypy_boto3_s3 import S3Client
 
-with try_import():
+with try_import() as _imports:
     import boto3
     from botocore.exceptions import ClientError
 
@@ -59,6 +59,7 @@ def objective(trial: optuna.Trial) -> float:
     def __init__(
         self, bucket_name: str, client: S3Client | None = None, *, avoid_buf_copy: bool = False
     ) -> None:
+        _imports.check()
         self.bucket = bucket_name
         self.client = client or boto3.client("s3")
         # This flag is added to avoid that upload_fileobj() method of Boto3 client may close the

optuna/artifacts/_gcs.py

@@ -11,7 +11,7 @@
 if TYPE_CHECKING:
     from typing import BinaryIO
 
-with try_import():
+with try_import() as _imports:
     import google.cloud.storage
 
 
@@ -61,6 +61,7 @@ def __init__(
         bucket_name: str,
         client: google.cloud.storage.Client | None = None,
     ) -> None:
+        _imports.check()
         self.bucket_name = bucket_name
         self.client = client or google.cloud.storage.Client()
         self.bucket_obj = self.client.bucket(bucket_name)