xemu/docs/devel/testing/avocado.rst

.. _checkavocado-ref:


Integration testing with Avocado
================================

The ``tests/avocado`` directory hosts integration tests. They're usually
higher level tests, and may interact with external resources and with
various guest operating systems.

These tests are written using the Avocado Testing Framework (which must be
installed separately) in conjunction with a the ``avocado_qemu.QemuSystemTest``
class, implemented at ``tests/avocado/avocado_qemu``.

Tests based on ``avocado_qemu.QemuSystemTest`` can easily:

 * Customize the command line arguments given to the convenience
   ``self.vm`` attribute (a QEMUMachine instance)

 * Interact with the QEMU monitor, send QMP commands and check
   their results

 * Interact with the guest OS, using the convenience console device
   (which may be useful to assert the effectiveness and correctness of
   command line arguments or QMP commands)

 * Interact with external data files that accompany the test itself
   (see ``self.get_data()``)

 * Download (and cache) remote data files, such as firmware and kernel
   images

 * Have access to a library of guest OS images (by means of the
   ``avocado.utils.vmimage`` library)

 * Make use of various other test related utilities available at the
   test class itself and at the utility library:

   - http://avocado-framework.readthedocs.io/en/latest/api/test/avocado.html#avocado.Test
   - http://avocado-framework.readthedocs.io/en/latest/api/utils/avocado.utils.html

Running tests
-------------

You can run the avocado tests simply by executing:

.. code::

  make check-avocado

This involves the automatic installation, from PyPI, of all the
necessary avocado-framework dependencies into the QEMU venv within the
build tree (at ``./pyvenv``). Test results are also saved within the
build tree (at ``tests/results``).

Note: the build environment must be using a Python 3 stack, and have
the ``venv`` and ``pip`` packages installed.  If necessary, make sure
``configure`` is called with ``--python=`` and that those modules are
available.  On Debian and Ubuntu based systems, depending on the
specific version, they may be on packages named ``python3-venv`` and
``python3-pip``.

It is also possible to run tests based on tags using the
``make check-avocado`` command and the ``AVOCADO_TAGS`` environment
variable:

.. code::

   make check-avocado AVOCADO_TAGS=quick

Note that tags separated with commas have an AND behavior, while tags
separated by spaces have an OR behavior. For more information on Avocado
tags, see:

 https://avocado-framework.readthedocs.io/en/latest/guides/user/chapters/tags.html

To run a single test file, a couple of them, or a test within a file
using the ``make check-avocado`` command, set the ``AVOCADO_TESTS``
environment variable with the test files or test names. To run all
tests from a single file, use:

 .. code::

  make check-avocado AVOCADO_TESTS=$FILEPATH

The same is valid to run tests from multiple test files:

 .. code::

  make check-avocado AVOCADO_TESTS='$FILEPATH1 $FILEPATH2'

To run a single test within a file, use:

 .. code::

  make check-avocado AVOCADO_TESTS=$FILEPATH:$TESTCLASS.$TESTNAME

The same is valid to run single tests from multiple test files:

 .. code::

  make check-avocado AVOCADO_TESTS='$FILEPATH1:$TESTCLASS1.$TESTNAME1 $FILEPATH2:$TESTCLASS2.$TESTNAME2'

The scripts installed inside the virtual environment may be used
without an "activation".  For instance, the Avocado test runner
may be invoked by running:

 .. code::

  pyvenv/bin/avocado run $OPTION1 $OPTION2 tests/avocado/

Note that if ``make check-avocado`` was not executed before, it is
possible to create the Python virtual environment with the dependencies
needed running:

 .. code::

  make check-venv

It is also possible to run tests from a single file or a single test within
a test file. To run tests from a single file within the build tree, use:

 .. code::

  pyvenv/bin/avocado run tests/avocado/$TESTFILE

To run a single test within a test file, use:

 .. code::

  pyvenv/bin/avocado run tests/avocado/$TESTFILE:$TESTCLASS.$TESTNAME

Valid test names are visible in the output from any previous execution
of Avocado or ``make check-avocado``, and can also be queried using:

 .. code::

  pyvenv/bin/avocado list tests/avocado

Manual Installation
-------------------

To manually install Avocado and its dependencies, run:

.. code::

  pip install --user avocado-framework

Alternatively, follow the instructions on this link:

  https://avocado-framework.readthedocs.io/en/latest/guides/user/chapters/installing.html

Overview
--------

The ``tests/avocado/avocado_qemu`` directory provides the
``avocado_qemu`` Python module, containing the ``avocado_qemu.QemuSystemTest``
class.  Here's a simple usage example:

.. code::

  from avocado_qemu import QemuSystemTest


  class Version(QemuSystemTest):
      """
      :avocado: tags=quick
      """
      def test_qmp_human_info_version(self):
          self.vm.launch()
          res = self.vm.cmd('human-monitor-command',
                            command_line='info version')
          self.assertRegex(res, r'^(\d+\.\d+\.\d)')

To execute your test, run:

.. code::

  avocado run version.py

Tests may be classified according to a convention by using docstring
directives such as ``:avocado: tags=TAG1,TAG2``.  To run all tests
in the current directory, tagged as "quick", run:

.. code::

  avocado run -t quick .

The ``avocado_qemu.QemuSystemTest`` base test class
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``avocado_qemu.QemuSystemTest`` class has a number of characteristics
that are worth being mentioned right away.

First of all, it attempts to give each test a ready to use QEMUMachine
instance, available at ``self.vm``.  Because many tests will tweak the
QEMU command line, launching the QEMUMachine (by using ``self.vm.launch()``)
is left to the test writer.

The base test class has also support for tests with more than one
QEMUMachine. The way to get machines is through the ``self.get_vm()``
method which will return a QEMUMachine instance. The ``self.get_vm()``
method accepts arguments that will be passed to the QEMUMachine creation
and also an optional ``name`` attribute so you can identify a specific
machine and get it more than once through the tests methods. A simple
and hypothetical example follows:

.. code::

  from avocado_qemu import QemuSystemTest


  class MultipleMachines(QemuSystemTest):
      def test_multiple_machines(self):
          first_machine = self.get_vm()
          second_machine = self.get_vm()
          self.get_vm(name='third_machine').launch()

          first_machine.launch()
          second_machine.launch()

          first_res = first_machine.cmd(
              'human-monitor-command',
              command_line='info version')

          second_res = second_machine.cmd(
              'human-monitor-command',
              command_line='info version')

          third_res = self.get_vm(name='third_machine').cmd(
              'human-monitor-command',
              command_line='info version')

          self.assertEqual(first_res, second_res, third_res)

At test "tear down", ``avocado_qemu.QemuSystemTest`` handles all the
QEMUMachines shutdown.

The ``avocado_qemu.LinuxTest`` base test class
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``avocado_qemu.LinuxTest`` is further specialization of the
``avocado_qemu.QemuSystemTest`` class, so it contains all the characteristics
of the later plus some extra features.

First of all, this base class is intended for tests that need to
interact with a fully booted and operational Linux guest.  At this
time, it uses a Fedora 31 guest image.  The most basic example looks
like this:

.. code::

  from avocado_qemu import LinuxTest


  class SomeTest(LinuxTest):

      def test(self):
          self.launch_and_wait()
          self.ssh_command('some_command_to_be_run_in_the_guest')

Please refer to tests that use ``avocado_qemu.LinuxTest`` under
``tests/avocado`` for more examples.

QEMUMachine
-----------

The QEMUMachine API is already widely used in the Python iotests,
device-crash-test and other Python scripts.  It's a wrapper around the
execution of a QEMU binary, giving its users:

 * the ability to set command line arguments to be given to the QEMU
   binary

 * a ready to use QMP connection and interface, which can be used to
   send commands and inspect its results, as well as asynchronous
   events

 * convenience methods to set commonly used command line arguments in
   a more succinct and intuitive way

QEMU binary selection
^^^^^^^^^^^^^^^^^^^^^

The QEMU binary used for the ``self.vm`` QEMUMachine instance will
primarily depend on the value of the ``qemu_bin`` parameter.  If it's
not explicitly set, its default value will be the result of a dynamic
probe in the same source tree.  A suitable binary will be one that
targets the architecture matching host machine.

Based on this description, test writers will usually rely on one of
the following approaches:

1) Set ``qemu_bin``, and use the given binary

2) Do not set ``qemu_bin``, and use a QEMU binary named like
   "qemu-system-${arch}", either in the current
   working directory, or in the current source tree.

The resulting ``qemu_bin`` value will be preserved in the
``avocado_qemu.QemuSystemTest`` as an attribute with the same name.

Attribute reference
-------------------

Test
^^^^

Besides the attributes and methods that are part of the base
``avocado.Test`` class, the following attributes are available on any
``avocado_qemu.QemuSystemTest`` instance.

vm
""

A QEMUMachine instance, initially configured according to the given
``qemu_bin`` parameter.

arch
""""

The architecture can be used on different levels of the stack, e.g. by
the framework or by the test itself.  At the framework level, it will
currently influence the selection of a QEMU binary (when one is not
explicitly given).

Tests are also free to use this attribute value, for their own needs.
A test may, for instance, use the same value when selecting the
architecture of a kernel or disk image to boot a VM with.

The ``arch`` attribute will be set to the test parameter of the same
name.  If one is not given explicitly, it will either be set to
``None``, or, if the test is tagged with one (and only one)
``:avocado: tags=arch:VALUE`` tag, it will be set to ``VALUE``.

cpu
"""

The cpu model that will be set to all QEMUMachine instances created
by the test.

The ``cpu`` attribute will be set to the test parameter of the same
name. If one is not given explicitly, it will either be set to
``None ``, or, if the test is tagged with one (and only one)
``:avocado: tags=cpu:VALUE`` tag, it will be set to ``VALUE``.

machine
"""""""

The machine type that will be set to all QEMUMachine instances created
by the test.

The ``machine`` attribute will be set to the test parameter of the same
name.  If one is not given explicitly, it will either be set to
``None``, or, if the test is tagged with one (and only one)
``:avocado: tags=machine:VALUE`` tag, it will be set to ``VALUE``.

qemu_bin
""""""""

The preserved value of the ``qemu_bin`` parameter or the result of the
dynamic probe for a QEMU binary in the current working directory or
source tree.

LinuxTest
^^^^^^^^^

Besides the attributes present on the ``avocado_qemu.QemuSystemTest`` base
class, the ``avocado_qemu.LinuxTest`` adds the following attributes:

distro
""""""

The name of the Linux distribution used as the guest image for the
test.  The name should match the **Provider** column on the list
of images supported by the avocado.utils.vmimage library:

https://avocado-framework.readthedocs.io/en/latest/guides/writer/libs/vmimage.html#supported-images

distro_version
""""""""""""""

The version of the Linux distribution as the guest image for the
test.  The name should match the **Version** column on the list
of images supported by the avocado.utils.vmimage library:

https://avocado-framework.readthedocs.io/en/latest/guides/writer/libs/vmimage.html#supported-images

distro_checksum
"""""""""""""""

The sha256 hash of the guest image file used for the test.

If this value is not set in the code or by a test parameter (with the
same name), no validation on the integrity of the image will be
performed.

Parameter reference
-------------------

To understand how Avocado parameters are accessed by tests, and how
they can be passed to tests, please refer to::

  https://avocado-framework.readthedocs.io/en/latest/guides/writer/chapters/writing.html#accessing-test-parameters

Parameter values can be easily seen in the log files, and will look
like the following:

.. code::

  PARAMS (key=qemu_bin, path=*, default=./qemu-system-x86_64) => './qemu-system-x86_64

Test
^^^^

arch
""""

The architecture that will influence the selection of a QEMU binary
(when one is not explicitly given).

Tests are also free to use this parameter value, for their own needs.
A test may, for instance, use the same value when selecting the
architecture of a kernel or disk image to boot a VM with.

This parameter has a direct relation with the ``arch`` attribute.  If
not given, it will default to None.

cpu
"""

The cpu model that will be set to all QEMUMachine instances created
by the test.

machine
"""""""

The machine type that will be set to all QEMUMachine instances created
by the test.

qemu_bin
""""""""

The exact QEMU binary to be used on QEMUMachine.

LinuxTest
^^^^^^^^^

Besides the parameters present on the ``avocado_qemu.QemuSystemTest`` base
class, the ``avocado_qemu.LinuxTest`` adds the following parameters:

distro
""""""

The name of the Linux distribution used as the guest image for the
test.  The name should match the **Provider** column on the list
of images supported by the avocado.utils.vmimage library:

https://avocado-framework.readthedocs.io/en/latest/guides/writer/libs/vmimage.html#supported-images

distro_version
""""""""""""""

The version of the Linux distribution as the guest image for the
test.  The name should match the **Version** column on the list
of images supported by the avocado.utils.vmimage library:

https://avocado-framework.readthedocs.io/en/latest/guides/writer/libs/vmimage.html#supported-images

distro_checksum
"""""""""""""""

The sha256 hash of the guest image file used for the test.

If this value is not set in the code or by this parameter no
validation on the integrity of the image will be performed.

Skipping tests
--------------

The Avocado framework provides Python decorators which allow for easily skip
tests running under certain conditions. For example, on the lack of a binary
on the test system or when the running environment is a CI system. For further
information about those decorators, please refer to::

  https://avocado-framework.readthedocs.io/en/latest/guides/writer/chapters/writing.html#skipping-tests

While the conditions for skipping tests are often specifics of each one, there
are recurring scenarios identified by the QEMU developers and the use of
environment variables became a kind of standard way to enable/disable tests.

Here is a list of the most used variables:

AVOCADO_ALLOW_LARGE_STORAGE
^^^^^^^^^^^^^^^^^^^^^^^^^^^
Tests which are going to fetch or produce assets considered *large* are not
going to run unless that ``AVOCADO_ALLOW_LARGE_STORAGE=1`` is exported on
the environment.

The definition of *large* is a bit arbitrary here, but it usually means an
asset which occupies at least 1GB of size on disk when uncompressed.

SPEED
^^^^^
Tests which have a long runtime will not be run unless ``SPEED=slow`` is
exported on the environment.

The definition of *long* is a bit arbitrary here, and it depends on the
usefulness of the test too. A unique test is worth spending more time on,
small variations on existing tests perhaps less so. As a rough guide,
a test or set of similar tests which take more than 100 seconds to
complete.

AVOCADO_ALLOW_UNTRUSTED_CODE
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
There are tests which will boot a kernel image or firmware that can be
considered not safe to run on the developer's workstation, thus they are
skipped by default. The definition of *not safe* is also arbitrary but
usually it means a blob which either its source or build process aren't
public available.

You should export ``AVOCADO_ALLOW_UNTRUSTED_CODE=1`` on the environment in
order to allow tests which make use of those kind of assets.

AVOCADO_TIMEOUT_EXPECTED
^^^^^^^^^^^^^^^^^^^^^^^^
The Avocado framework has a timeout mechanism which interrupts tests to avoid the
test suite of getting stuck. The timeout value can be set via test parameter or
property defined in the test class, for further details::

  https://avocado-framework.readthedocs.io/en/latest/guides/writer/chapters/writing.html#setting-a-test-timeout

Even though the timeout can be set by the test developer, there are some tests
that may not have a well-defined limit of time to finish under certain
conditions. For example, tests that take longer to execute when QEMU is
compiled with debug flags. Therefore, the ``AVOCADO_TIMEOUT_EXPECTED`` variable
has been used to determine whether those tests should run or not.

QEMU_TEST_FLAKY_TESTS
^^^^^^^^^^^^^^^^^^^^^
Some tests are not working reliably and thus are disabled by default.
This includes tests that don't run reliably on GitLab's CI which
usually expose real issues that are rarely seen on developer machines
due to the constraints of the CI environment. If you encounter a
similar situation then raise a bug and then mark the test as shown on
the code snippet below:

.. code::

  # See https://gitlab.com/qemu-project/qemu/-/issues/nnnn
  @skipUnless(os.getenv('QEMU_TEST_FLAKY_TESTS'), 'Test is unstable on GitLab')
  def test(self):
      do_something()

You can also add ``:avocado: tags=flaky`` to the test meta-data so
only the flaky tests can be run as a group:

.. code::

   env QEMU_TEST_FLAKY_TESTS=1 ./pyvenv/bin/avocado \
      run tests/avocado -filter-by-tags=flaky

Tests should not live in this state forever and should either be fixed
or eventually removed.


Uninstalling Avocado
--------------------

If you've followed the manual installation instructions above, you can
easily uninstall Avocado.  Start by listing the packages you have
installed::

  pip list --user

And remove any package you want with::

  pip uninstall <package_name>

If you've used ``make check-avocado``, the Python virtual environment where
Avocado is installed will be cleaned up as part of ``make check-clean``.