Merge pull request #125372 from Synthetica9/shell_interact

nixos/tests/test-driver: add shell_interact

nixos/doc/manual/development/writing-nixos-tests.xml

@@ -436,6 +436,18 @@ machine.systemctl("list-jobs --no-pager", "any-user") # spawns a shell for `any-
      </para>
     </listitem>
    </varlistentry>
+   <varlistentry>
+    <term>
+     <methodname>shell_interact</methodname>
+    </term>
+    <listitem>
+     <para>
+      Allows you to directly interact with the guest shell.
+      This should only be used during test development, not in production tests.
+      Killing the interactive session with <literal>Ctrl-d</literal> or <literal>Ctrl-c</literal> also ends the guest session.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </para>
 

nixos/lib/test-driver/test-driver.py

@@ -21,6 +21,7 @@ import shutil
 import socket
 import subprocess
 import sys
+import telnetlib
 import tempfile
 import time
 import traceback
@@ -455,6 +456,16 @@ class Machine:
                 return (status_code, output)
             output += chunk
 
+    def shell_interact(self) -> None:
+        """Allows you to interact with the guest shell
+
+        Should only be used during test development, not in the production test."""
+        self.connect()
+        self.log("Terminal is ready (there is no prompt):")
+        telnet = telnetlib.Telnet()
+        telnet.sock = self.shell  # type: ignore
+        telnet.interact()
+
     def succeed(self, *commands: str) -> str:
         """Execute each command and check that it succeeds."""
         output = ""