diff --git a/tests/conftest.py b/tests/conftest.py
index 866ba89..fa9b405 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -3,8 +3,8 @@
 from fastapi.testclient import TestClient
 import pytest
 import os
-
 import pytest_asyncio
+from httpx._types import HeaderTypes
 
 from transcriptomics_data_service.db import Database, get_db
 from transcriptomics_data_service.logger import get_logger
@@ -56,3 +56,11 @@ def test_client(db: Database):
     with TestClient(app) as client:
         app.dependency_overrides[get_db] = get_test_db
         yield client
+
+
+@pytest.fixture
+def authz_headers(config) -> HeaderTypes:
+    api_key = config.model_extra.get("api_key")
+    return {
+        "x-api-key": api_key
+    }
diff --git a/tests/test_authz_plugin.py b/tests/test_authz_plugin.py
new file mode 100644
index 0000000..d12d2ab
--- /dev/null
+++ b/tests/test_authz_plugin.py
@@ -0,0 +1,8 @@
+from transcriptomics_data_service.authz.plugin import import_module_from_path
+
+
+def test_import_authz_plugin_disabled():
+    config = lambda: None
+    config.bento_authz_enabled = False
+    authz_plugin = import_module_from_path("", config)
+    assert authz_plugin == None
diff --git a/tests/test_expressions.py b/tests/test_expressions.py
new file mode 100644
index 0000000..bc71e20
--- /dev/null
+++ b/tests/test_expressions.py
@@ -0,0 +1,18 @@
+from fastapi import status
+from fastapi.testclient import TestClient
+from transcriptomics_data_service.config import get_config
+from transcriptomics_data_service.logger import get_logger
+
+
+config = get_config()
+logger = get_logger(config)
+
+api_key = config.model_extra.get("api_key")
+
+def test_expressions_unauthorized(test_client: TestClient):
+    response = test_client.get("/expressions")
+    assert response.status_code == status.HTTP_400_BAD_REQUEST
+
+def test_expressions_authorized(test_client: TestClient, authz_headers):
+    response = test_client.get("/expressions", headers=authz_headers)
+    assert response.status_code == status.HTTP_200_OK
diff --git a/transcriptomics_data_service/authz/plugin.py b/transcriptomics_data_service/authz/plugin.py
index e1a097f..6a2a7e2 100644
--- a/transcriptomics_data_service/authz/plugin.py
+++ b/transcriptomics_data_service/authz/plugin.py
@@ -6,10 +6,7 @@
 
 __all__ = ["authz_plugin"]
 
-config = get_config()
-
-
-def import_module_from_path(path) -> None | ModuleType:
+def import_module_from_path(path, config) -> None | ModuleType:
     if config.bento_authz_enabled:
         spec = importlib.util.spec_from_file_location("authz_plugin", path)
         module = importlib.util.module_from_spec(spec)
@@ -20,4 +17,6 @@ def import_module_from_path(path) -> None | ModuleType:
 
 
 # Get the concrete authz middleware from the provided plugin module
-authz_plugin: BaseAuthzMiddleware = import_module_from_path("./lib/authz.module.py")
+authz_plugin: BaseAuthzMiddleware = import_module_from_path(
+    "./lib/authz.module.py", get_config()
+)