The test itself can be run interactively. This is particularly useful when developing or debugging a test: $ nix-build . -A nixosTests.login.driverInteractive $ ./result/bin/nixos-test-driver [...] >>> You can then take any Python statement, e.g. >>> start_all() >>> test_script() >>> machine.succeed("touch /tmp/foo") >>> print(machine.succeed("pwd")) # Show stdout of command The function test_script executes the entire test script and drops you back into the test driver command line upon its completion. This allows you to inspect the state of the VMs after the test (e.g. to debug the test script).

You can re-use the VM states coming from a previous run by setting the --keep-vm-state flag. $ ./result/bin/nixos-test-driver --keep-vm-state The machine state is stored in the $TMPDIR/vm-state-machinename directory.

The .driverInteractive attribute combines the regular test configuration with definitions from the interactive submodule. This gives you a more usable, graphical, but slightly different configuration. You can add your own interactive-only test configuration by adding extra configuration to the interactive submodule. To interactively run only the regular configuration, build the <test>.driver attribute instead, and call it with the flag result/bin/nixos-test-driver --interactive.