Add kiosk smoke test for secondary platforms

.github/workflows/test.yml

@@ -43,6 +43,21 @@ jobs:
     - uses: DeterminateSystems/magic-nix-cache-action@v4
     - run: cd kiosk && nix-shell --run bin/test
 
+  kiosk-smoke-tests:
+    # While the smoke test should run on other platforms, it does not currently
+    # run on GitHub's Ubuntu runners, as they don't support GUI applications.
+    runs-on: macos-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
+    - uses: cachix/install-nix-action@v18
+      with:
+        nix_path: nixpkgs=channel:nixos-unstable
+    - name: Smoke Test
+      run: cd kiosk && nix-shell --run "python test/platform-smoke.py"
+
   build-vm:
     runs-on: ubuntu-latest
     steps:

kiosk/test/platform-smoke.py

@@ -0,0 +1,65 @@
+import http.server
+import socket
+import socketserver
+import threading
+import subprocess
+import time
+
+PORT = 45678
+request_count = 0
+
+def main():
+    """Checks that the kiosk-browser does not crash immediately on start and makes a request to the provided URL.
+
+    This serves as a minimal test to make sure the kiosk can run on different platforms.
+    """
+
+    # Start dummy web server in thread, with signal to stop
+    keep_running = threading.Event()
+    keep_running.set()
+    server_thread = threading.Thread(target=run_server, args=(keep_running,))
+    server_thread.start()
+    time.sleep(1)
+
+    try:
+        browser_process = subprocess.Popen(['bin/kiosk-browser', f'http://localhost:{PORT}', f'http://localhost:{PORT}'])
+        time.sleep(5)
+
+        # Minimal expectations
+        assert browser_process.poll() is None, "Browser process has crashed."
+        assert request_count >= 1, "No requests were made to the server."
+
+        print("Smoke test passed successfully.")
+
+    finally:
+        # Send signal to stop web server and wait for completion
+        keep_running.clear()
+        server_thread.join()
+
+        # Terminate the browser process
+        browser_process.terminate()
+
+class RequestHandler(http.server.SimpleHTTPRequestHandler):
+    """Default request handler with added counter."""
+    def do_GET(self):
+        global request_count
+        request_count += 1
+        # Call superclass method to actually serve the request
+        super().do_GET()
+
+def run_server(keep_running):
+    """Run the web server, checking whether to keep running frequently."""
+    with socketserver.TCPServer(("", PORT), RequestHandler, bind_and_activate=False) as httpd:
+        # Let address be reused to avoid failure on repeated runs
+        httpd.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        httpd.server_bind()
+        httpd.server_activate()
+        # Timeout frequently to check if killed
+        httpd.timeout = 0.5
+        try:
+            while keep_running.is_set():
+                httpd.handle_request()
+        finally:
+            httpd.server_close()
+
+main()