diff --git a/test/test_execution.py b/test/test_execution.py
index 20e821e4..d0357076 100644
--- a/test/test_execution.py
+++ b/test/test_execution.py
@@ -1,6 +1,5 @@
 import os
 from pathlib import Path
-import shutil
 from unittest import mock
 import pytest
 from utils import assert_files
@@ -10,9 +9,10 @@
 
 
 @pytest.fixture
-def temp_output_dir(tmp_path):
-    yield str(tmp_path) + os.sep
-    shutil.rmtree(tmp_path)
+def temp_output_dir(tmp_path: Path) -> str:
+    # Append path separator so that value is recognized as a directory when
+    # passed to `output_prefix`
+    return str(tmp_path) + os.sep
 
 
 def test_sanity_green(temp_output_dir):
diff --git a/test/utils.py b/test/utils.py
index d62899dc..f5ba0d43 100644
--- a/test/utils.py
+++ b/test/utils.py
@@ -16,10 +16,10 @@ def assert_files(parent_dir, file_list, exists=True):
     if exists:
         for file_path in file_list:
             assert Path(
-                parent_dir + file_path
+                parent_dir, file_path
             ).exists(), f"Expected file does not exist: {file_path}"
     else:
         for file_path in file_list:
             assert not Path(
-                parent_dir + file_path
+                parent_dir, file_path
             ).exists(), f"Unexpected file should not exist: {file_path}"