Deal with the case when await_request() returns None…

…indicating "there are no more requests this session". It's an `optional` in the WIT, though it never returned `None` before. I suspect multi-request is never happening anymore. Perhaps something changed in Viceroy, but this crash happens in Viceroy's `erik/python-sdk-compatible-2` and `main` (80c9e1486e5bbe559ec0194714bb668988984993). The crash happens *after* the request is served, so CI didn't catch it. It does now.

Also add tests for Game Of Life.

Author: erikrose

examples/game-of-life.py

@@ -43,9 +43,8 @@ def decompressed_board(compressed: str) -> str:
 
 @app.route("/board/<compressed_board>")
 def board(compressed_board: str):
-    """Return the next frame of the Game Of Life, given the current one. If a ""
-    board is given, return a new random board.
-    """
+    """Return the next frame of the Game Of Life, given the current one. If "none"
+    is given instead, return a new random board."""
     cells = decompressed_board(compressed_board)
 
     # Random board on start:

fastly_compute/wsgi.py

@@ -208,6 +208,8 @@ def handle(self, request: Any, body: Any) -> None:
                     # Something went wrong.
                     raise
             else:
+                if not result:
+                    break
                 request, body = result
                 serve_wsgi_request(
                     request,

tests/test_game_of_life_example.py

@@ -0,0 +1,49 @@
+import re
+from time import sleep
+
+from fastly_compute.testing import ViceroyTestBase
+
+
+class TestGameOfLife(ViceroyTestBase):
+    """Integration tests for the Game Of Life example"""
+
+    WASM_FILE = "build/game-of-life.composed.wasm"
+
+    def test_root(self):
+        """Show that the page full of JS at least loads."""
+        response = self.get("/")
+        assert response.status_code == 200
+        assert "async function startAnimation" in response.text
+
+    def test_random_board(self):
+        """Show that random boards are generated for the first frame."""
+        response = self.get("/board/none")
+        assert response.status_code == 200
+        assert re.match(r"[01]+", response.text)
+
+    def test_evolved_board(self):
+        """Show that a new board is correctly computed from an old one."""
+        response = self.get(
+            "/board/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAcAAAAAAAAAAAAAAAAEAAAAAAABAAAAAHAAQAAAAAAAAAAAAAAAcAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAAAAKAAAAAAAEgAAAAAAAwAADAAAAAAAN6AAAAAACscAAAAAAoOAGAAAAGACBgAAAAAAgAAAAAAAgAAAAAAAsAAAAAAAIAwAAAAAAgSAAAAAAAEgAAAAAAAwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHAAAAAAAAQAAAAAAAOADAAAAAAAAwAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
+        )
+        assert response.status_code == 200
+        assert (
+            response.text
+            == "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000001210000000000000000000000000000000002000000000000000000000000000000000000000000000000010000000000010000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000202000000000000000000000000000000000000000000000020020000000000000000000000000000000000000000000000022000000000000000000010010000000000000000000000000000000000000000000231000300110000000000000000000000000000000000000003030001100020000000000000000000000000000000000000020300000200100000000033000000000000000000000000000032000000100000000000330000000000000000000000000000000000000000100000000000000000000000000000000000000000000000120000000000000000000000000000000000000000000000000220000000000000000000000000000000000000000000000001100000022000000000000000000000000000000000000000000000002002000000000000000000000000000000000000000000000020020000000000000000000000000000000000000000000000022000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000003200000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000232000000000003300000000000000000000000000000000000100000000000033000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+        )
+
+    def test_reuse_sandboxes(self):
+        """Make sure attempting to issue multiple requests to a single sandbox doesn't crash.
+
+        This does not test whether a single sandbox actually served multiple
+        requests; 2 sandboxes could have served 1 request each.
+        """
+        response = self.get("/board/none")
+        assert response.status_code == 200
+        response = self.get("/board/none")
+        assert response.status_code == 200
+
+        # The error about failed sandbox reuse comes *after* the request has
+        # succeeded. And it seems to take forever to show up.
+        sleep(4)  # 2 is not enough. I am sad.
+        assert "WebAssembly trapped" not in "\n".join(self.server.output_lines)