Isolated test runner for functional tests (qemu + 9p + serial)

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I’ve written about this before, functional testing of operating system features, i.e. messing with storage or network devices.

In the last post I used gherkin, pexpect and qemu to do this. It works, but was still to cumbersome.

This time I’ve further reduced the dependencies and made the process simpler and more mature.

The flow is now roughly as follows:

  • Write testcases on the host-side
  • Run a VM, and loop in some host-side dir, i.e. $PWD using 9pfs over virtio, and attach the serial console of the VM to stdio
  • Wait for some keyword to turn up and send the necessary client side commands to mount the host-side path into some dir
  • Change into the mounted path and run the host-side testcases inside the VM

Asciiart:

Job          Workspace                        VM

Init   -->   Populated

             Spawn a VM                  -->  Boot

             Pass workspace using 9pfs   -->  Mount workspace over
                                              9pfs

             Init test through serial io -->  Test runner runs
                                         <--  Write results to
                                              workspace through
                                              9pfs

                                              Shutdown

This doesn’t sound fancy, but it has some nice aspects:

  • No modification of the VM needed, as long as the serial console is used
  • Reduce the interaction with the VM to a minimum (but is general enough to have low assumptions about the VM)
  • Works nicely with Jenkins, because libvirt is not involved
  • Don’t touch the image by using snapshots
  • The tests can do whatever they want, complete isolation
  • Simple to understand and maintain
  • Few constraints on the host
  • Works with docker too?

To highlight the key achievements:

  • 9pfs is used to easily exchange data between host and guest.
  • Kickoff testing within the VM using the virtio serial

An example for this approach can be found here

  • it used to test some Node experiments.

The actual tests and test-runner can be found here.

::: {#footer} [ October 2nd, 2014 4:15pm ]{#timestamp} [qemu]{.tag} [fedora]{.tag} [ovirt]{.tag} [node]{.tag} [libvirt]{.tag} [test]{.tag} [automation]{.tag} :::