test(ai-agent): add unit tests for POST /transfers/analyse LLM path (#146)

Author: iduhtheman

apps/ai_agent/tests/test_transfers.py

@@ -0,0 +1,89 @@
+from fastapi.testclient import TestClient
+from unittest.mock import MagicMock, patch
+import json
+import pytest
+
+from main import app
+
+client = TestClient(app)
+
+
+# Helper to build a fake OpenAI response
+def _fake_openai_response(payload: dict):
+    msg = MagicMock()
+    msg.content = json.dumps(payload)
+    choice = MagicMock()
+    choice.message = msg
+    resp = MagicMock()
+    resp.choices = [choice]
+    return resp
+
+
+def test_llm_path_flagged_transfer():
+    with patch("main._openai_client") as mock_client_fn:
+        mock_client = MagicMock()
+        mock_client_fn.return_value = mock_client
+        mock_client.chat.completions.create.return_value = _fake_openai_response(
+            {"flagged": True, "reason": "Suspicious memo", "confidence": 0.9}
+        )
+        response = client.post("/transfers/analyse", json={
+            "amount": 100.0, "sender": "GABC", "recipient": "GDEF", "memo": "test"
+        })
+        assert response.status_code == 200
+        data = response.json()
+        assert data["flagged"] is True
+        assert data["confidence"] == 0.9
+
+
+def test_llm_path_clean_transfer():
+    with patch("main._openai_client") as mock_client_fn:
+        mock_client = MagicMock()
+        mock_client_fn.return_value = mock_client
+        mock_client.chat.completions.create.return_value = _fake_openai_response(
+            {"flagged": False, "reason": None, "confidence": 0.1}
+        )
+        response = client.post("/transfers/analyse", json={
+            "amount": 500.0, "sender": "GABC", "recipient": "GDEF", "memo": "payment"
+        })
+        assert response.status_code == 200
+        data = response.json()
+        assert data["flagged"] is False
+        assert isinstance(data["confidence"], float)
+
+
+def test_llm_path_missing_confidence_defaults_to_zero():
+    with patch("main._openai_client") as mock_client_fn:
+        mock_client = MagicMock()
+        mock_client_fn.return_value = mock_client
+        mock_client.chat.completions.create.return_value = _fake_openai_response(
+            {"flagged": False, "reason": None}
+        )
+        response = client.post("/transfers/analyse", json={
+            "amount": 200.0, "sender": "GABC", "recipient": "GDEF", "memo": "normal"
+        })
+        assert response.status_code == 200
+        data = response.json()
+        assert data["confidence"] == 0.0
+
+
+def test_llm_path_missing_flagged_defaults_to_false():
+    with patch("main._openai_client") as mock_client_fn:
+        mock_client = MagicMock()
+        mock_client_fn.return_value = mock_client
+        mock_client.chat.completions.create.return_value = _fake_openai_response(
+            {"reason": None, "confidence": 0.5}
+        )
+        response = client.post("/transfers/analyse", json={
+            "amount": 300.0, "sender": "GABC", "recipient": "GDEF", "memo": "salary"
+        })
+        assert response.status_code == 200
+        data = response.json()
+        assert data["flagged"] is False
+
+
+def test_llm_path_missing_api_key_returns_500(monkeypatch):
+    monkeypatch.delenv("OPENAI_API_KEY", raising=False)
+    response = client.post("/transfers/analyse", json={
+        "amount": 100.0, "sender": "GABC", "recipient": "GDEF", "memo": "test"
+    })
+    assert response.status_code == 500