<section xmlns="http://docbook.org/ns/docbook"
        xmlns:xlink="http://www.w3.org/1999/xlink"
        xmlns:xi="http://www.w3.org/2001/XInclude"
        version="5.0"
        xml:id="sec-running-nixos-tests-interactively">

<title>Running Tests</title>

<para>You can run tests using <command>nix-build</command>. For
example, to run the test <filename
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/nixos/tests/login.nix">login.nix</filename>,
you just do:

<screen>
$ nix-build '&lt;nixpkgs/nixos/tests/login.nix>'
</screen>

or, if you don’t want to rely on <envar>NIX_PATH</envar>:

<screen>
$ cd /my/nixpkgs/nixos/tests
$ nix-build login.nix
…
running the VM test script
machine: QEMU running (pid 8841)
…
6 out of 6 tests succeeded
</screen>

After building/downloading all required dependencies, this will
perform a build that starts a QEMU/KVM virtual machine containing a
NixOS system. The virtual machine mounts the Nix store of the host;
this makes VM creation very fast, as no disk image needs to be
created. Afterwards, you can view a pretty-printed log of the test:

<screen>
$ firefox result/log.html
</screen>

</para>
</section>
