Add JSON-safe serialization

tests/test_serialization.py

@@ -0,0 +1,57 @@
+import contextlib
+import io
+import unittest
+
+from fastapi.encoders import jsonable_encoder
+from fastapi.testclient import TestClient
+
+from ipython_demo import App, Shell
+from ipython_webapp.app import app as web_app
+
+
+class SerializationTests(unittest.TestCase):
+    def test_call_result_stays_raw_until_to_response(self):
+        shell = Shell("raw-result")
+
+        with contextlib.redirect_stdout(io.StringIO()):
+            result, _events = shell.run_cell(
+                "plt.plot([1, 2, 3], [4, 5, 6])",
+                call_id="raw-call",
+            )
+
+        self.assertIn("Line2D", repr(result.result))
+        response = result.to_response()
+        self.assertIsNone(response.result)
+        self.assertIn("Line2D", response.result_repr)
+
+    def test_matplotlib_result_is_safe_for_web_serialization(self):
+        app = App()
+
+        with contextlib.redirect_stdout(io.StringIO()):
+            response = app.run_code(
+                "plt.plot([1, 2, 3], [4, 5, 6])",
+                shell_name="new",
+            )
+
+        encoded = jsonable_encoder(response)
+
+        self.assertIsNone(response.result.result)
+        self.assertIn("Line2D", response.result.result_repr)
+        self.assertIsNone(encoded["result"]["result"])
+        self.assertIn("Line2D", encoded["result"]["result_repr"])
+
+    def test_plot_route_returns_dto_instead_of_recursion_error(self):
+        response = TestClient(web_app).post(
+            "/shells/http-plot/run",
+            content="plt.plot([1, 2, 3], [4, 5, 6])",
+            headers={"content-type": "text/plain"},
+        )
+
+        self.assertEqual(response.status_code, 200)
+        payload = response.json()
+        self.assertIsNone(payload["result"]["result"])
+        self.assertIn("Line2D", payload["result"]["result_repr"])
+
+
+if __name__ == "__main__":
+    unittest.main()