nixos/tests/nixos-test-driver: test timeout failures

We test that the test framework timeouts are working as expected.

nixos/tests/all-tests.nix

···
     lib-extend = handleTestOn [ "x86_64-linux" "aarch64-linux" ] ./nixos-test-driver/lib-extend.nix {};
     node-name = runTest ./nixos-test-driver/node-name.nix;
     busybox = runTest ./nixos-test-driver/busybox.nix;
+    driver-timeout = pkgs.runCommand "ensure-timeout-induced-failure" {
+      failed = pkgs.testers.testBuildFailure ((runTest ./nixos-test-driver/timeout.nix).config.rawTestDerivation);
+    } ''
+      grep -F "timeout reached; test terminating" $failed/testBuildFailure.log
+      # The program will always be terminated by SIGTERM (143) if it waits for the deadline thread.
+      [[ 143 = $(cat $failed/testBuildFailure.exit) ]]
+      touch $out
+    '';
   };
 
   # NixOS vm tests and non-vm unit tests

nixos/tests/nixos-test-driver/timeout.nix

···
+{
+  name = "Test that sleep of 6 seconds fails a timeout of 5 seconds";
+  globalTimeout = 5;
+
+  nodes = {
+    machine = ({ pkgs, ... }: {
+    });
+  };
+
+  testScript = ''
+    start_all()
+    machine.wait_for_unit("multi-user.target")
+    machine.succeed("sleep 6")
+  '';
+}