Wait for installer exit and live shell before followup probes

tests/test_iso_smoke.py

@@ -2,6 +2,7 @@
 import importlib.util
 from pathlib import Path
 import socket
+import select
 import subprocess
 import tempfile
 import threading
@@ -152,6 +153,35 @@ class SmokeTests(unittest.TestCase):
             console.expect_installer(rb'Repeat password: ', 0.05, 'testtoken')
         self.assertNotIn('test-secret', str(caught.exception))
 
+    def test_installer_followup_waits_for_exit_and_new_shell_prompt(self):
+        console, guest = self.installer_console()
+        premature = []
+        def respond():
+            guest.sendall(b'Installation completed. Diagnostic log: /run/installer.log\r\n')
+            premature.append(bool(select.select([guest], [], [], 0.05)[0]))
+            guest.sendall(b'\x1etesttoken:INSTALL_EXIT:0\x1f')
+            premature.append(bool(select.select([guest], [], [], 0.05)[0]))
+            guest.sendall(b'\x1b[?2004hhydra-live@hydra-os ~ $ ')
+            data = b''
+            while not data.endswith(b'\n'):
+                data += guest.recv(65536)
+            result = subprocess.run(['/bin/sh', '-c', data.decode()], capture_output=True)
+            guest.sendall(result.stdout)
+        worker = threading.Thread(target=respond, daemon=True)
+        worker.start()
+        console.expect_installer(rb'Installation completed\. Diagnostic log: [^\r\n]+',
+                                 1, 'testtoken')
+        console.finish_installer('testtoken', timeout=1)
+        self.assertEqual(console.command('printf ready', timeout=1), b'ready')
+        worker.join(timeout=1)
+        self.assertEqual(premature, [False, False], 'command reached installer before shell was ready')
+
+    def test_installer_completion_does_not_override_nonzero_return(self):
+        console, guest = self.installer_console()
+        guest.sendall(b'\x1etesttoken:INSTALL_EXIT:1\x1fhydra-live@hydra-os ~ $ ')
+        with self.assertRaisesRegex(self.mod.SmokeError, 'Installer.*status 1'):
+            console.finish_installer('testtoken', timeout=0.05)
+
     def test_frame_real_shell_roundtrip_does_not_accept_sentinel_in_echo(self):
         one, two = socket.socketpair()
         self.addCleanup(one.close)