diff --git a/src/frostfs_testlib/clients/http/__init__.py b/src/frostfs_testlib/clients/http/__init__.py
index e69de29..ab6e2b0 100644
--- a/src/frostfs_testlib/clients/http/__init__.py
+++ b/src/frostfs_testlib/clients/http/__init__.py
@@ -0,0 +1 @@
+from frostfs_testlib.clients.http.http_client import HttpClient
diff --git a/src/frostfs_testlib/clients/s3/__init__.py b/src/frostfs_testlib/clients/s3/__init__.py
index 65a3990..5481f48 100644
--- a/src/frostfs_testlib/clients/s3/__init__.py
+++ b/src/frostfs_testlib/clients/s3/__init__.py
@@ -1 +1,3 @@
-from frostfs_testlib.clients.s3.interfaces import BucketContainerResolver, S3ClientWrapper, VersioningStatus
+from frostfs_testlib.clients.s3.aws_cli_client import AwsCliClient
+from frostfs_testlib.clients.s3.boto3_client import Boto3ClientWrapper
+from frostfs_testlib.clients.s3.interfaces import ACL, BucketContainerResolver, S3ClientWrapper, VersioningStatus
diff --git a/src/frostfs_testlib/clients/s3/aws_cli_client.py b/src/frostfs_testlib/clients/s3/aws_cli_client.py
index accc289..8b2d774 100644
--- a/src/frostfs_testlib/clients/s3/aws_cli_client.py
+++ b/src/frostfs_testlib/clients/s3/aws_cli_client.py
@@ -33,12 +33,14 @@ class AwsCliClient(S3ClientWrapper):
         self, access_key_id: str, secret_access_key: str, s3gate_endpoint: str, profile: str = "default", region: str = "us-east-1"
     ) -> None:
         self.s3gate_endpoint = s3gate_endpoint
+        self.iam_endpoint = None
+
         self.access_key_id: str = access_key_id
         self.secret_access_key: str = secret_access_key
         self.profile = profile
-        self.local_shell = LocalShell()
         self.region = region
-        self.iam_endpoint = None
+
+        self.local_shell = LocalShell()
         try:
             _configure_aws_cli(f"aws configure --profile {profile}", access_key_id, secret_access_key, region)
             self.local_shell.exec(f"aws configure set max_attempts {MAX_REQUEST_ATTEMPTS} --profile {profile}")
diff --git a/src/frostfs_testlib/clients/s3/boto3_client.py b/src/frostfs_testlib/clients/s3/boto3_client.py
index 890b4e9..9d9fefe 100644
--- a/src/frostfs_testlib/clients/s3/boto3_client.py
+++ b/src/frostfs_testlib/clients/s3/boto3_client.py
@@ -35,26 +35,20 @@ class Boto3ClientWrapper(S3ClientWrapper):
     def __init__(
         self, access_key_id: str, secret_access_key: str, s3gate_endpoint: str, profile: str = "default", region: str = "us-east-1"
     ) -> None:
-        self.boto3_client: S3Client = None
         self.s3gate_endpoint: str = ""
+        self.boto3_client: S3Client = None
 
-        self.boto3_iam_client: S3Client = None
         self.iam_endpoint: str = ""
-
+        self.boto3_iam_client: S3Client = None
         self.boto3_sts_client: S3Client = None
 
-        self.access_key_id: str = access_key_id
-        self.secret_access_key: str = secret_access_key
+        self.access_key_id = access_key_id
+        self.secret_access_key = secret_access_key
         self.profile = profile
         self.region = region
 
         self.session = boto3.Session()
-        self.config = Config(
-            retries={
-                "max_attempts": MAX_REQUEST_ATTEMPTS,
-                "mode": RETRY_MODE,
-            }
-        )
+        self.config = Config(retries={"max_attempts": MAX_REQUEST_ATTEMPTS, "mode": RETRY_MODE})
 
         self.set_endpoint(s3gate_endpoint)
 
@@ -90,7 +84,7 @@ class Boto3ClientWrapper(S3ClientWrapper):
             endpoint_url=self.iam_endpoint,
             verify=False,
         )
-        # since the STS does not have an enpoint, IAM is used
+        # since the STS does not have an endpoint, IAM is used
         self.boto3_sts_client = self.session.client(
             service_name="sts",
             aws_access_key_id=self.access_key_id,
@@ -145,6 +139,7 @@ class Boto3ClientWrapper(S3ClientWrapper):
         params = {"Bucket": bucket}
         if object_lock_enabled_for_bucket is not None:
             params.update({"ObjectLockEnabledForBucket": object_lock_enabled_for_bucket})
+
         if acl is not None:
             params.update({"ACL": acl})
         elif grant_write or grant_read or grant_full_control:
@@ -154,6 +149,7 @@ class Boto3ClientWrapper(S3ClientWrapper):
                 params.update({"GrantRead": grant_read})
             elif grant_full_control:
                 params.update({"GrantFullControl": grant_full_control})
+
         if location_constraint:
             params.update({"CreateBucketConfiguration": {"LocationConstraint": location_constraint}})
 
diff --git a/src/frostfs_testlib/clients/s3/interfaces.py b/src/frostfs_testlib/clients/s3/interfaces.py
index 7ce9f31..d636182 100644
--- a/src/frostfs_testlib/clients/s3/interfaces.py
+++ b/src/frostfs_testlib/clients/s3/interfaces.py
@@ -22,15 +22,15 @@ class VersioningStatus(HumanReadableEnum):
     SUSPENDED = "Suspended"
 
 
-ACL_COPY = [
-    "private",
-    "public-read",
-    "public-read-write",
-    "authenticated-read",
-    "aws-exec-read",
-    "bucket-owner-read",
-    "bucket-owner-full-control",
-]
+class ACL:
+    PRIVATE = "private"
+    PUBLIC_READ = "public-read"
+    PUBLIC_READ_WRITE = "public-read-write"
+    AUTHENTICATED_READ = "authenticated-read"
+    AWS_EXEC_READ = "aws-exec-read"
+    BUCKET_OWNER_READ = "bucket-owner-read"
+    BUCKET_OWNER_FULL_CONTROL = "bucket-owner-full-control"
+    LOG_DELIVERY_WRITE = "log-delivery-write"
 
 
 class BucketContainerResolver(ABC):
@@ -50,6 +50,14 @@ class BucketContainerResolver(ABC):
 
 
 class S3ClientWrapper(HumanReadableABC):
+    access_key_id: str
+    secret_access_key: str
+    profile: str
+    region: str
+
+    s3gate_endpoint: str
+    iam_endpoint: str
+
     @abstractmethod
     def __init__(self, access_key_id: str, secret_access_key: str, s3gate_endpoint: str, profile: str, region: str) -> None:
         pass
diff --git a/src/frostfs_testlib/resources/error_patterns.py b/src/frostfs_testlib/resources/error_patterns.py
index 4c22648..6c0cb14 100644
--- a/src/frostfs_testlib/resources/error_patterns.py
+++ b/src/frostfs_testlib/resources/error_patterns.py
@@ -1,5 +1,6 @@
 # Regex patterns of status codes of Container service
 CONTAINER_NOT_FOUND = "code = 3072.*message = container not found"
+SUBJECT_NOT_FOUND = "code = 1024.*message = frostfs error: chain/client.*subject not found.*"
 
 # Regex patterns of status codes of Object service
 MALFORMED_REQUEST = "code = 1024.*message = malformed request"