Unit test for empty AWS variables
diff --git a/tests/detect_aws_credentials_test.py b/tests/detect_aws_credentials_test.py
index 777fb48..46e5b36 100644
--- a/tests/detect_aws_credentials_test.py
+++ b/tests/detect_aws_credentials_test.py
@@ -47,6 +47,8 @@
         ({'AWS_SECRET_ACCESS_KEY': 'foo'}, {'foo'}),
         ({'AWS_SECURITY_TOKEN': 'foo'}, {'foo'}),
         ({'AWS_SESSION_TOKEN': 'foo'}, {'foo'}),
+        ({'AWS_SESSION_TOKEN': ''}, set()),
+        ({'AWS_SESSION_TOKEN': 'foo', 'AWS_SECURITY_TOKEN': ''}, {'foo'}),
         ({'AWS_DUMMY_KEY': 'foo', 'AWS_SECRET_ACCESS_KEY': 'bar'}, {'bar'}),
         (
             {'AWS_SECRET_ACCESS_KEY': 'foo', 'AWS_SECURITY_TOKEN': 'bar'},