diff --git a/test_stream_agent.py b/test_stream_agent.py
new file mode 100644
index 0000000..901a0a2
--- /dev/null
+++ b/test_stream_agent.py
@@ -0,0 +1,18 @@
+from stream_agent import StreamingAIAgent
+
+
+def test_stream_returns_chunks(monkeypatch):
+    monkeypatch.delenv("OPENAI_API_KEY", raising=False)
+    agent = StreamingAIAgent()
+
+    chunks = list(agent.stream("test question"))
+
+    assert len(chunks) > 3
+    assert "".join(chunks).strip()
+
+
+def test_invoke_matches_stream(monkeypatch):
+    monkeypatch.delenv("OPENAI_API_KEY", raising=False)
+    agent = StreamingAIAgent()
+
+    assert agent.invoke("hello") == "".join(agent.stream("hello"))