Add failing test

tests/test_s3fs_minio.py

@@ -1,3 +1,4 @@
+import os
 from typing import NamedTuple
 
 from minimalkv import get_store_from_url
@@ -13,21 +14,23 @@ class User(NamedTuple):
     # user2 -> bucket2
     # Including one bucket_name per `User` here is just for readability
 
+    def get_store_from_config(self):
+        return get_store_from_url(
+            f"hs3://{self.access_key}:{self.secret_key}@localhost:9000/{self.bucket_name}?force_bucket_suffix=false&verify=false"
+        )
+
+
+user1 = User("user1", "password1", "bucket1")
+user2 = User("user2", "password2", "bucket2")
+
 
 def test_access_multiple_users():
     """Verify that two buckets of different users can be accessed in the same python process."""
-    user1 = User("user1", "password1", "bucket1")
-    user2 = User("user2", "password2", "bucket2")
-
-    bucket1 = get_store_from_url(
-        f"hs3://{user1.access_key}:{user1.secret_key}@localhost:9000/{user1.bucket_name}?force_bucket_suffix=false&verify=false"
-    )
+    bucket1 = user1.get_store_from_config()
 
     assert bucket1.keys() == ["file1.txt"]
 
-    bucket2 = get_store_from_url(
-        f"hs3://{user2.access_key}:{user2.secret_key}@localhost:9000/{user2.bucket_name}?force_bucket_suffix=false&verify=false"
-    )
+    bucket2 = user2.get_store_from_config()
 
     assert bucket2.keys() == ["file2.txt"]
 
@@ -41,11 +44,9 @@ def test_example_interaction():
     - get()
     - delete()
     """
-    user = User("user1", "password1", "bucket1")
+    # TODO: Replace w/ testing strategy as done in `test_boto3_store.py`
 
-    bucket = get_store_from_url(
-        f"hs3://{user.access_key}:{user.secret_key}@localhost:9000/{user.bucket_name}?force_bucket_suffix=false&verify=false"
-    )
+    bucket = user1.get_store_from_config()
 
     new_filename = "some-non-existing-file"
     new_content = b"content"
@@ -58,3 +59,19 @@ def test_example_interaction():
 
     bucket.delete(new_filename)
     assert new_filename not in bucket.keys()
+
+
+def test_no_env_side_effects():
+    pre_env_state = os.environ.copy()
+
+    bucket = user1.get_store_from_config()
+
+    assert dict(os.environ) == dict(
+        pre_env_state
+    ), "Retrieved bucket should not modify the environment."
+
+    bucket.keys()
+
+    assert (
+        os.environ == pre_env_state
+    ), "Performing operations on the bucket should not modify the environment."