WritingTests.rst

.. _writing-tests:

=====================
Writing Avocado Tests
=====================

We are going to write an Avocado test in Python and we are going to inherit from
:class:`avocado.Test`. This makes this test a so-called instrumented test.

Basic example
=============

Let's re-create an old time favorite, ``sleeptest`` [#f1]_.  It is so simple, it
does nothing besides sleeping for a while::

        import time

        from avocado import Test

        class SleepTest(Test):

            def test(self):
                sleep_length = self.params.get('sleep_length', default=1)
                self.log.debug("Sleeping for %.2f seconds", sleep_length)
                time.sleep(sleep_length)

This is about the simplest test you can write for Avocado, while still
leveraging its API power.

What is an Avocado Test
-----------------------

As can be seen in the example above, an Avocado test is a method that
starts with ``test`` in a class that inherits from :mod:`avocado.Test`.

Multiple tests and naming conventions
-------------------------------------

You can have multiple tests in a single class.

To do so, just give the methods names that start with ``test``, say
``test_foo``, ``test_bar`` and so on. We recommend you follow this naming
style, as defined in the `PEP8 Function Names`_ section.

For the class name, you can pick any name you like, but we also recommend
that it follows the CamelCase convention, also known as CapWords, defined
in the PEP 8 document under `Class Names`_.

Convenience Attributes
----------------------

Note that the test class provides you with a number of convenience attributes:

* A ready to use log mechanism for your test, that can be accessed by means
  of ``self.log``. It lets you log debug, info, error and warning messages.
* A parameter passing system (and fetching system) that can be accessed by
  means of ``self.params``. This is hooked to the Multiplexer, about which
  you can find that more information at :doc:`MultiplexConfig`.

Saving test generated (custom) data
===================================

Each test instance provides a so called ``whiteboard``. It can be accessed
through ``self.whiteboard``. This whiteboard is simply a string that will be
automatically saved to test results (as long as the output format supports it).
If you choose to save binary data to the whiteboard, it's your responsibility to
encode it first (base64 is the obvious choice).

Building on the previously demonstrated ``sleeptest``, suppose that you want to save the
sleep length to be used by some other script or data analysis tool::

        def test(self):
            sleep_length = self.params.get('sleep_length', default=1)
            self.log.debug("Sleeping for %.2f seconds", sleep_length)
            time.sleep(sleep_length)
            self.whiteboard = "%.2f" % sleep_length

The whiteboard can and should be exposed by files generated by the available test result
plugins. The ``results.json`` file already includes the whiteboard for each test.
Additionally, we'll save a raw copy of the whiteboard contents on a file named
``whiteboard``, in the same level as the ``results.json`` file, for your convenience
(maybe you want to use the result of a benchmark directly with your custom made scripts
to analyze that particular benchmark result).

Accessing test parameters
=========================

Each test has a set of parameters that can be accessed through
``self.params.get($name, $path=None, $default=None)``.
Avocado finds and populates ``self.params`` with all parameters you define on
a Multiplex Config file (see :doc:`MultiplexConfig`). As an example, consider
the following multiplex file for sleeptest::

    sleeptest:
        type: "builtin"
        length: !mux
            short:
                sleep_length: 0.5
            medium:
                sleep_length: 1
            long:
                sleep_length: 5

When running this example by ``avocado run $test --multiplex $file.yaml``
three variants are executed and the content is injected into ``/run`` namespace
(see :doc:`MultiplexConfig` for details). Every variant contains variables
"type" and "sleep_length". To obtain the current value, you need the name
("sleep_length") and its path. The path differs for each variant so it's
needed to use the most suitable portion of the path, in this example:
`/run/sleeptest/length/*` or perhaps `sleeptest/*` might be enough. It depends
on how your setup looks like.

The default value is optional, but always keep in mind to handle them nicely.
Someone might be executing your test with different params or without any
params at all. It should work fine.

So the complete example on how to access the "sleep_length" would be::

    self.params.get("sleep_length", "/*/sleeptest/*", 1)

There is one way to make this even simpler. It's possible to define resolution
order, then for simple queries you can simply omit the path::

    self.params.get("sleep_length", None, 1)
    self.params.get("sleep_length", '*', 1)
    self.params.get("sleep_length", default=1)

One should always try to avoid param clashes (multiple matching keys for given
path with different origin). If it's not possible (eg. when
you use multiple yaml files) you can modify the default paths by modifying
``--mux-path``. What it does is it slices the params and iterates through the
paths one by one. When there is a match in the first slice it returns
it without trying the other slices. Although relative queries only match
from ``--mux-path`` slices.

There are many ways to use paths to separate clashing params or just to make
more clear what your query for. Usually in tests the usage of '*' is sufficient
and the namespacing is not necessarily, but it helps make advanced usage
clearer and easier to follow.

When thinking of the path always think about users. It's common to extend
default config with additional variants or combine them with different
ones to generate just the right scenarios they need. People might
simply inject the values elsewhere (eg. `/run/sleeptest` =>
`/upstream/sleeptest`) or they can merge other clashing file into the
default path, which won't generate clash, but would return their values
instead. Then you need to clarify the path (eg. `'*'` =>  `sleeptest/*`)

More details on that are in :doc:`MultiplexConfig`

Using a multiplex file
======================

You may use the Avocado runner with a multiplex file to provide params and matrix
generation for sleeptest just like::

    $ avocado run sleeptest --multiplex examples/tests/sleeptest.py.data/sleeptest.yaml
    JOB ID    : d565e8dec576d6040f894841f32a836c751f968f
    JOB LOG   : $HOME/avocado/job-results/job-2014-08-12T15.44-d565e8de/job.log
    TESTS     : 3
     (1/3) sleeptest: PASS (0.50 s)
     (2/3) sleeptest.1: PASS (1.01 s)
     (3/3) sleeptest.2: PASS (5.01 s)
    RESULTS    : PASS 3 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    JOB HTML  : $HOME/avocado/job-results/job-2014-08-12T15.44-d565e8de/html/results.html
    TIME : 6.52 s

The ``--multiplex`` accepts either only ``$FILE_LOCATION`` or ``$INJECT_TO:$FILE_LOCATION``.
As explained in :doc:`MultiplexConfig` without any path the content gets
injected into ``/run`` in order to be in the default relative path location.
The ``$INJECT_TO`` can be either relative path, then it's injected into
``/run/$INJECT_TO`` location, or absolute path (starting with ``'/'``), then
it's injected directly into the specified path and it's up to the test/framework
developer to get the value from this location (using path or adding the path to
``mux-path``). To understand the difference execute those commands::

    $ avocado multiplex -t examples/tests/sleeptest.py.data/sleeptest.yaml
    $ avocado multiplex -t duration:examples/tests/sleeptest.py.data/sleeptest.yaml
    $ avocado multiplex -t /my/location:examples/tests/sleeptest.py.data/sleeptest.yaml

Note that, as your multiplex file specifies all parameters for sleeptest, you
can't leave the test ID empty::

    $ scripts/avocado run --multiplex examples/tests/sleeptest/sleeptest.yaml
    Empty test ID. A test path or alias must be provided

You can also execute multiple tests with the same multiplex file::

    ./scripts/avocado run sleeptest synctest --multiplex examples/tests/sleeptest.py.data/sleeptest.yaml
    JOB ID     : 72166988c13fec26fcc9c2e504beec8edaad4761
    JOB LOG    : /home/medic/avocado/job-results/job-2015-05-15T11.02-7216698/job.log
    TESTS      : 8
     (1/8) sleeptest.py: PASS (1.00 s)
     (2/8) sleeptest.py.1: PASS (1.00 s)
     (3/8) sleeptest.py.2: PASS (1.00 s)
     (4/8) sleeptest.py.3: PASS (1.00 s)
     (5/8) synctest.py: PASS (1.31 s)
     (6/8) synctest.py.1: PASS (1.48 s)
     (7/8) synctest.py.2: PASS (3.36 s)
     (8/8) synctest.py.3: PASS (3.59 s)
    RESULTS    : PASS 8 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    JOB HTML   : /home/medic/avocado/job-results/job-2015-05-15T11.02-7216698/html/results.html
    TIME       : 13.76 s

Advanced logging capabilities
=============================

Avocado provides advanced logging capabilities at test run time.  These can
be combined with the standard Python library APIs on tests.

One common example is the need to follow specific progress on longer or more
complex tests. Let's look at a very simple test example, but one multiple
clear stages on a single test::

    import logging
    import time

    from avocado import Test

    progress_log = logging.getLogger("progress")

    class Plant(Test):

        def test_plant_organic(self):
            rows = self.params.get("rows", default=3)

            # Preparing soil
            for row in range(rows):
                progress_log.info("%s: preparing soil on row %s",
                                  self.tagged_name, row)

            # Letting soil rest
            progress_log.info("%s: letting soil rest before throwing seeds",
                              self.tagged_name)
            time.sleep(2)

            # Throwing seeds
            for row in range(rows):
                progress_log.info("%s: throwing seeds on row %s",
                                  self.tagged_name, row)

            # Let them grow
            progress_log.info("%s: waiting for Avocados to grow",
                              self.tagged_name)
            time.sleep(5)

            # Harvest them
            for row in range(rows):
                progress_log.info("%s: harvesting organic avocados on row %s",
                                  self.tagged_name, row)


From this point on, you can ask Avocado to show your logging stream, either
exclusively or in addition to other builtin streams::

    $ avocado --show app,progress run plant.py

The outcome should be similar to::

    JOB ID     : af786f86db530bff26cd6a92c36e99bedcdca95b
    JOB LOG    : /home/cleber/avocado/job-results/job-2016-03-18T10.29-af786f8/job.log
    TESTS      : 1
     (1/1) plant.py:Plant.test_plant_organic:  progress: plant.py:Plant.test_plant_organic: preparing soil on row 0
    progress: plant.py:Plant.test_plant_organic: preparing soil on row 1
    progress: plant.py:Plant.test_plant_organic: preparing soil on row 2
    progress: plant.py:Plant.test_plant_organic: letting soil rest before throwing seeds
    -progress: plant.py:Plant.test_plant_organic: throwing seeds on row 0
    progress: plant.py:Plant.test_plant_organic: throwing seeds on row 1
    progress: plant.py:Plant.test_plant_organic: throwing seeds on row 2
    progress: plant.py:Plant.test_plant_organic: waiting for Avocados to grow
    \progress: plant.py:Plant.test_plant_organic: harvesting organic avocados on row 0
    progress: plant.py:Plant.test_plant_organic: harvesting organic avocados on row 1
    progress: plant.py:Plant.test_plant_organic: harvesting organic avocados on row 2
    PASS
    RESULTS    : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    JOB HTML   : /home/cleber/avocado/job-results/job-2016-03-18T10.29-af786f8/html/results.html
    TIME       : 7.01 s

The custom ``progress`` stream is combined with the application output, which
may or may not suit your needs or preferences. If you want the ``progress``
stream to be sent to a separate file, both for clarity and for persistence,
you can run Avocado like this::

    $ avocado run plant.py --store-logging-stream progress

The result is that, besides all the other log files commonly generated, there
will be another log file named ``progress.INFO`` at the job results
dir. During the test run, one could watch the progress with::

    $ tail -f ~/avocado/job-results/latest/progress.INFO
    10:36:59 INFO | plant.py:Plant.test_plant_organic: preparing soil on row 0
    10:36:59 INFO | plant.py:Plant.test_plant_organic: preparing soil on row 1
    10:36:59 INFO | plant.py:Plant.test_plant_organic: preparing soil on row 2
    10:36:59 INFO | plant.py:Plant.test_plant_organic: letting soil rest before throwing seeds
    10:37:01 INFO | plant.py:Plant.test_plant_organic: throwing seeds on row 0
    10:37:01 INFO | plant.py:Plant.test_plant_organic: throwing seeds on row 1
    10:37:01 INFO | plant.py:Plant.test_plant_organic: throwing seeds on row 2
    10:37:01 INFO | plant.py:Plant.test_plant_organic: waiting for Avocados to grow
    10:37:06 INFO | plant.py:Plant.test_plant_organic: harvesting organic avocados on row 0
    10:37:06 INFO | plant.py:Plant.test_plant_organic: harvesting organic avocados on row 1
    10:37:06 INFO | plant.py:Plant.test_plant_organic: harvesting organic avocados on row 2

The very same ``progress`` logger, could be used across multiple test methods
and across multiple test modules.  In the example given, the tagged test name
is used to give extra context.

:class:`unittest.TestCase` heritage
===================================

Since an Avocado test inherits from :class:`unittest.TestCase`, you
can use all the assertion methods that its parent.

The code example bellow uses :meth:`assertEqual
<unittest.TestCase.assertEqual>`, :meth:`assertTrue
<unittest.TestCase.assertTrue>` and :meth:`assertIsInstace
<unittest.TestCase.assertIsInstance>`::

    from avocado import Test

    class RandomExamples(Test):
        def test(self):
            self.log.debug("Verifying some random math...")
            four = 2 * 2
            four_ = 2 + 2
            self.assertEqual(four, four_, "something is very wrong here!")

            self.log.debug("Verifying if a variable is set to True...")
            variable = True
            self.assertTrue(variable)

            self.log.debug("Verifying if this test is an instance of test.Test")
            self.assertIsInstance(self, test.Test)

Running tests under other :mod:`unittest` runners
-------------------------------------------------

`nose <https://nose.readthedocs.org/>`__ is another Python testing framework
that is also compatible with :mod:`unittest`.

Because of that, you can run avocado tests with the ``nosetests`` application::

    $ nosetests examples/tests/sleeptest.py
    .
    ----------------------------------------------------------------------
    Ran 1 test in 1.004s

    OK

Conversely, you can also use the standard :func:`unittest.main` entry point to run an
Avocado test. Check out the following code, to be saved as ``dummy.py``::

   from avocado import Test
   from unittest import main

   class Dummy(Test):
       def test(self):
           self.assertTrue(True)

   if __name__ == '__main__':
       main()

It can be run by::

   $ python dummy.py
   .
   ----------------------------------------------------------------------
   Ran 1 test in 0.000s

   OK

Setup and cleanup methods
=========================

If you need to perform setup actions before/after your test, you may do so
in the ``setUp`` and ``tearDown`` methods, respectively. We'll give examples
in the following section.

Running third party test suites
===============================

It is very common in test automation workloads to use test suites developed
by third parties. By wrapping the execution code inside an Avocado test module,
you gain access to the facilities and API provided by the framework. Let's
say you want to pick up a test suite written in C that it is in a tarball,
uncompress it, compile the suite code, and then executing the test. Here's
an example that does that::

    #!/usr/bin/env python

    import os

    from avocado import Test
    from avocado import main
    from avocado.utils import archive
    from avocado.utils import build
    from avocado.utils import process


    class SyncTest(Test):

        """
        Execute the synctest test suite.
        """
        default_params = {'sync_tarball': 'synctest.tar.bz2',
                          'sync_length': 100,
                          'sync_loop': 10}

        def setUp(self):
            """
            Set default params and build the synctest suite.
            """
            # Build the synctest suite
            self.cwd = os.getcwd()
            tarball_path = os.path.join(self.datadir, self.params.sync_tarball)
            archive.extract(tarball_path, self.srcdir)
            self.srcdir = os.path.join(self.srcdir, 'synctest')
            build.make(self.srcdir)

        def test(self):
            """
            Execute synctest with the appropriate params.
            """
            os.chdir(self.srcdir)
            cmd = ('./synctest %s %s' %
                   (self.params.sync_length, self.params.sync_loop))
            process.system(cmd)
            os.chdir(self.cwd)


    if __name__ == "__main__":
        main()

Here we have an example of the ``setUp`` method in action: Here we get the
location of the test suite code (tarball) through
:meth:`avocado.Test.datadir`, then uncompress the tarball through
:func:`avocado.utils.archive.extract`, an API that will
decompress the suite tarball, followed by :func:`avocado.utils.build.make`, that will build
the suite.

The ``setUp`` method is the only place in avocado where you are allowed to
call the ``skip`` method, given that, if a test started to be executed, by
definition it can't be skipped anymore. Avocado will do its best to enforce
this boundary, so that if you use ``skip`` outside ``setUp``, the test upon
execution will be marked with the ``ERROR`` status, and the error message
will instruct you to fix your test's code.

In this example, the ``test`` method just gets into the base directory of
the compiled suite  and executes the ``./synctest`` command, with appropriate
parameters, using :func:`avocado.utils.process.system`.

Fetching asset files
====================
To run third party test suites as mentioned above, or for any other pourpose,
we offer an asset fetcher as a method of Avocado Test class.
The asset method looks for a list of directories in the ``cache_dirs`` key,
inside the ``[datadir.paths]`` section from the configuration files. Read-only
directories are also supported. When the asset file is not present in any of
the provided directories, we will try to download the file from the provided
locations, copying it to the first writable cache directory. Example::

    cache_dirs = ['/usr/local/src/', '~/avocado/cache']

In the example above, ``/usr/local/src/`` is a read-only directory. In that
case, when we need to fetch the asset from the locations, it will be copied to
the ``~/avocado/cache`` directory.

If you don't provide a ``cache_dirs``, we will create a ``cache`` directory
inside the avocado ``data_dir`` location to put the fetched files in.

* Use case 1: no ``cache_dirs`` key in config files, only the asset name
  provided in the full url format::

    ...
        def setUp(self):
            stress = 'http://people.seas.harvard.edu/~apw/stress/stress-1.0.4.tar.gz'
            tarball = self.fetch_asset(stress)
            archive.extract(tarball, self.srcdir)
    ...

  In this case, ``fetch_asset()`` will download the file from the url provided,
  copying it to the ``$data_dir/cache`` directory. ``tarball`` variable  will
  contains, for example, ``/home/user/avocado/data/cache/stress-1.0.4.tar.gz``.

* Use case 2: Read-only cache directory provided. ``cache_dirs = ['/mnt/files']``::

    ...
        def setUp(self):
            stress = 'http://people.seas.harvard.edu/~apw/stress/stress-1.0.4.tar.gz'
            tarball = self.fetch_asset(stress)
            archive.extract(tarball, self.srcdir)
    ...

  In this case, we try to find ``stress-1.0.4.tar.gz`` file in ``/mnt/files``
  directory. If it's not there, since ``/mnt/files`` is read-only,  we will try
  to download the asset file to the ``$data_dir/cache`` directory.

* Use case 3: Writable cache directory provided, along with a list of
  locations. ``cache_dirs = ['~/avocado/cache']``::

    ...
        def setUp(self):
            st_name = 'stress-1.0.4.tar.gz'
            st_hash = 'e1533bc704928ba6e26a362452e6db8fd58b1f0b'
            st_loc = ['http://people.seas.harvard.edu/~apw/stress/stress-1.0.4.tar.gz',
                      'ftp://foo.bar/stress-1.0.4.tar.gz']
            tarball = self.fetch_asset(st_name, asset_hash=st_hash,
                                       locations=st_loc)
            archive.extract(tarball, self.srcdir)
    ...

  In this case, we try to download ``stress-1.0.4.tar.gz`` from the provided
  locations list (if it's not already in ``~/avocado/cache``). The hash was
  also provided, so we will verify the hash. To do so, we first look for a
  hashfile named ``stress-1.0.4.tar.gz.sha1`` in the same directory. If the
  hashfile is not present we compute the hash and create the hashfile for
  further usage.

  The resulting ``tarball`` variable content will be
  ``~/avocado/cache/stress-1.0.4.tar.gz``.
  An exception will take place if we fail to download or to verify the file.


Detailing the ``fetch_asset()`` attributes:

* ``name:`` The name used to name the fetched file. It can also contains a full
  URL, that will be used as the first location to try (after serching into the
  cache directories).
* ``asset_hash:`` (optional) The expected file hash. If missing, we skip the
  check. If provided, before computing the hash, we look for a hashfile to
  verify the asset. If the hashfile is nor present, we compute the hash and
  create the hashfile in the same cache directory for further usage.
* ``algorithm:`` (optional) Provided hash algorithm format. Defaults to sha1.
* ``locations:`` (optional) List of locations that will be used to try to fetch
  the file from. The supported schemes are ``http://``, ``https://``,
  ``ftp://`` and ``file://``. You're required to inform the full url to the
  file, including the file name. The first success will skip the next
  locations. Notice that for ``file://`` we just create a symbolic link in the
  cache directory, pointing to the file original location.

The expected ``return`` is the asset file path or an exception.

Test Output Check and Output Record Mode
========================================

In a lot of occasions, you want to go simpler: just check if the output of a
given application matches an expected output. In order to help with this common
use case, we offer the option ``--output-check-record [mode]`` to the test runner::

      --output-check-record OUTPUT_CHECK_RECORD
                            Record output streams of your tests to reference files
                            (valid options: none (do not record output streams),
                            all (record both stdout and stderr), stdout (record
                            only stderr), stderr (record only stderr). Default:
                            none

If this option is used, it will store the stdout or stderr of the process (or
both, if you specified ``all``) being executed to reference files: ``stdout.expected``
and ``stderr.expected``. Those files will be recorded in the test data dir. The
data dir is in the same directory as the test source file, named
``[source_file_name.data]``. Let's take as an example the test ``synctest.py``. In a
fresh checkout of Avocado, you can see::

        examples/tests/synctest.py.data/stderr.expected
        examples/tests/synctest.py.data/stdout.expected

From those 2 files, only stdout.expected is non empty::

    $ cat examples/tests/synctest.py.data/stdout.expected
    PAR : waiting
    PASS : sync interrupted

The output files were originally obtained using the test runner and passing the
option --output-check-record all to the test runner::

    $ scripts/avocado run --output-check-record all synctest
    JOB ID    : bcd05e4fd33e068b159045652da9eb7448802be5
    JOB LOG   : $HOME/avocado/job-results/job-2014-09-25T20.20-bcd05e4/job.log
    TESTS     : 1
     (1/1) synctest.py: PASS (2.20 s)
    RESULTS    : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    TIME      : 2.20 s


After the reference files are added, the check process is transparent, in the sense
that you do not need to provide special flags to the test runner.
Now, every time the test is executed, after it is done running, it will check
if the outputs are exactly right before considering the test as PASSed. If you want to override the default
behavior and skip output check entirely, you may provide the flag ``--output-check=off`` to the test runner.

The :mod:`avocado.utils.process` APIs have a parameter ``allow_output_check`` (defaults to ``all``), so that you
can select which process outputs will go to the reference files, should you chose to record them. You may choose
``all``, for both stdout and stderr, ``stdout``, for the stdout only, ``stderr``, for only the stderr only, or ``none``,
to allow neither of them to be recorded and checked.

This process works fine also with simple tests, which are programs or shell scripts
that returns 0 (PASSed) or != 0 (FAILed). Let's consider our bogus example::

    $ cat output_record.sh
    #!/bin/bash
    echo "Hello, world!"

Let's record the output for this one::

    $ scripts/avocado run output_record.sh --output-check-record all
    JOB ID    : 25c4244dda71d0570b7f849319cd71fe1722be8b
    JOB LOG   : $HOME/avocado/job-results/job-2014-09-25T20.49-25c4244/job.log
    TESTS     : 1
     (1/1) home/$USER/Code/avocado/output_record.sh: PASS (0.01 s)
    RESULTS    : PASS 1 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    TIME      : 0.01 s

After this is done, you'll notice that a the test data directory
appeared in the same level of our shell script, containing 2 files::

    $ ls output_record.sh.data/
    stderr.expected  stdout.expected

Let's look what's in each of them::

    $ cat output_record.sh.data/stdout.expected
    Hello, world!
    $ cat output_record.sh.data/stderr.expected
    $

Now, every time this test runs, it'll take into account the expected files that
were recorded, no need to do anything else but run the test. Let's see what
happens if we change the ``stdout.expected`` file contents to ``Hello, Avocado!``::

    $ scripts/avocado run output_record.sh
    JOB ID    : f0521e524face93019d7cb99c5765aedd933cb2e
    JOB LOG   : $HOME/avocado/job-results/job-2014-09-25T20.52-f0521e5/job.log
    TESTS     : 1
     (1/1) home/$USER/Code/avocado/output_record.sh: FAIL (0.02 s)
    RESULTS    : PASS 0 | ERROR 0 | FAIL 1 | SKIP 0 | WARN 0 | INTERRUPT 0
    TIME      : 0.02 s

Verifying the failure reason::

    $ cat $HOME/avocado/job-results/job-2014-09-25T20.52-f0521e5/job.log
    20:52:38 test       L0163 INFO | START home/$USER/Code/avocado/output_record.sh
    20:52:38 test       L0164 DEBUG|
    20:52:38 test       L0165 DEBUG| Test instance parameters:
    20:52:38 test       L0173 DEBUG|
    20:52:38 test       L0176 DEBUG| Default parameters:
    20:52:38 test       L0180 DEBUG|
    20:52:38 test       L0181 DEBUG| Test instance params override defaults whenever available
    20:52:38 test       L0182 DEBUG|
    20:52:38 process    L0242 INFO | Running '$HOME/Code/avocado/output_record.sh'
    20:52:38 process    L0310 DEBUG| [stdout] Hello, world!
    20:52:38 test       L0565 INFO | Command: $HOME/Code/avocado/output_record.sh
    20:52:38 test       L0565 INFO | Exit status: 0
    20:52:38 test       L0565 INFO | Duration: 0.00313782691956
    20:52:38 test       L0565 INFO | Stdout:
    20:52:38 test       L0565 INFO | Hello, world!
    20:52:38 test       L0565 INFO |
    20:52:38 test       L0565 INFO | Stderr:
    20:52:38 test       L0565 INFO |
    20:52:38 test       L0060 ERROR|
    20:52:38 test       L0063 ERROR| Traceback (most recent call last):
    20:52:38 test       L0063 ERROR|   File "$HOME/Code/avocado/avocado/test.py", line 397, in check_reference_stdout
    20:52:38 test       L0063 ERROR|     self.assertEqual(expected, actual, msg)
    20:52:38 test       L0063 ERROR|   File "/usr/lib64/python2.7/unittest/case.py", line 551, in assertEqual
    20:52:38 test       L0063 ERROR|     assertion_func(first, second, msg=msg)
    20:52:38 test       L0063 ERROR|   File "/usr/lib64/python2.7/unittest/case.py", line 544, in _baseAssertEqual
    20:52:38 test       L0063 ERROR|     raise self.failureException(msg)
    20:52:38 test       L0063 ERROR| AssertionError: Actual test sdtout differs from expected one:
    20:52:38 test       L0063 ERROR| Actual:
    20:52:38 test       L0063 ERROR| Hello, world!
    20:52:38 test       L0063 ERROR|
    20:52:38 test       L0063 ERROR| Expected:
    20:52:38 test       L0063 ERROR| Hello, Avocado!
    20:52:38 test       L0063 ERROR|
    20:52:38 test       L0064 ERROR|
    20:52:38 test       L0529 ERROR| FAIL home/$USER/Code/avocado/output_record.sh -> AssertionError: Actual test sdtout differs from expected one:
    Actual:
    Hello, world!

    Expected:
    Hello, Avocado!

    20:52:38 test       L0516 INFO |

As expected, the test failed because we changed its expectations.

Test log, stdout and stderr in native Avocado modules
=====================================================

If needed, you can write directly to the expected stdout and stderr files
from the native test scope. It is important to make the distinction between
the following entities:

* The test logs
* The test expected stdout
* The test expected stderr

The first one is used for debugging and informational purposes. Additionally
writing to `self.log.warning` causes test to be marked as dirty and when
everything else goes well the test ends with WARN. This means that the test
passed but there were non-related unexpected situations described in warning
log.

You may log something into the test logs using the methods in
:mod:`avocado.Test.log` class attributes. Consider the example::

    class output_test(Test):

        def test(self):
            self.log.info('This goes to the log and it is only informational')
            self.log.warn('Oh, something unexpected, non-critical happened, '
                          'but we can continue.')
            self.log.error('Describe the error here and don't forget to raise '
                           'an exception yourself. Writing to self.log.error '
                           'won't do that for you.')
            self.log.debug('Everybody look, I had a good lunch today...')

If you need to write directly to the test stdout and stderr streams,
Avocado makes two preconfigured loggers available for that purpose,
named ``avocado.test.stdout`` and ``avocado.test.stderr``. You can use
Python's standard logging API to write to them. Example::

    import logging

    class output_test(Test):

        def test(self):
            stdout = logging.getLogger('avocado.test.stdout')
            stdout.info('Informational line that will go to stdout')
            ...
            stderr = logging.getLogger('avocado.test.stderr')
            stderr.info('Informational line that will go to stderr')

Avocado will automatically save anything a test generates on STDOUT
into a ``stdout`` file, to be found at the test results directory. The same
applies to anything a test generates on STDERR, that is, it will be saved
into a ``stderr`` file at the same location.

Additionally, when using the runner's output recording features,
namely the ``--output-check-record`` argument with values ``stdout``,
``stderr`` or ``all``, everything given to those loggers will be saved
to the files ``stdout.expected`` and ``stderr.expected`` at the test's
data directory (which is different from the job/test results directory).

Avocado Tests run on a separate process
=======================================

In order to avoid tests to mess around the environment used by the main
Avocado runner process, tests are run on a forked subprocess. This allows
for more robustness (tests are not easily able to mess/break Avocado) and
some nifty features, such as setting test timeouts.

Setting a Test Timeout
======================

Sometimes your test suite/test might get stuck forever, and this might
impact your test grid. You can account for that possibility and set up a
``timeout`` parameter for your test. The test timeout can be set through
2 means, in the following order of precedence:

* Multiplex variable parameters. You may just set the timeout parameter, like
  in the following simplistic example:

::

    sleep_length = 5
    sleep_length_type = float
    timeout = 3
    timeout_type = float

::

    $ avocado run sleeptest --multiplex /tmp/sleeptest-example.yaml
    JOB ID    : 6d5a2ff16bb92395100fbc3945b8d253308728c9
    JOB LOG   : $HOME/avocado/job-results/job-2014-08-12T15.52-6d5a2ff1/job.log
    JOB HTML  : $HOME/avocado/job-results/job-2014-08-12T15.52-6d5a2ff1/html/results.html
    TESTS     : 1
     (1/1) sleeptest.1: ERROR (2.97 s)
    RESULTS    : PASS 0 | ERROR 1 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    TIME      : 2.97 s

::

    $ cat $HOME/avocado/job-results/job-2014-08-12T15.52-6d5a2ff1/job.log
    15:52:51 test       L0143 INFO | START sleeptest.1
    15:52:51 test       L0144 DEBUG|
    15:52:51 test       L0145 DEBUG| Test log: $HOME/avocado/job-results/job-2014-08-12T15.52-6d5a2ff1/sleeptest.1/test.log
    15:52:51 test       L0146 DEBUG| Test instance parameters:
    15:52:51 test       L0153 DEBUG|     _name_map_file = {'sleeptest-example.yaml': 'sleeptest'}
    15:52:51 test       L0153 DEBUG|     _short_name_map_file = {'sleeptest-example.yaml': 'sleeptest'}
    15:52:51 test       L0153 DEBUG|     dep = []
    15:52:51 test       L0153 DEBUG|     id = sleeptest
    15:52:51 test       L0153 DEBUG|     name = sleeptest
    15:52:51 test       L0153 DEBUG|     shortname = sleeptest
    15:52:51 test       L0153 DEBUG|     sleep_length = 5.0
    15:52:51 test       L0153 DEBUG|     sleep_length_type = float
    15:52:51 test       L0153 DEBUG|     timeout = 3.0
    15:52:51 test       L0153 DEBUG|     timeout_type = float
    15:52:51 test       L0154 DEBUG|
    15:52:51 test       L0157 DEBUG| Default parameters:
    15:52:51 test       L0159 DEBUG|     sleep_length = 1.0
    15:52:51 test       L0161 DEBUG|
    15:52:51 test       L0162 DEBUG| Test instance params override defaults whenever available
    15:52:51 test       L0163 DEBUG|
    15:52:51 test       L0169 INFO | Test timeout set. Will wait 3.00 s for PID 15670 to end
    15:52:51 test       L0170 INFO |
    15:52:51 sleeptest  L0035 DEBUG| Sleeping for 5.00 seconds
    15:52:54 test       L0057 ERROR|
    15:52:54 test       L0060 ERROR| Traceback (most recent call last):
    15:52:54 test       L0060 ERROR|   File "$HOME/Code/avocado/tests/sleeptest.py", line 36, in action
    15:52:54 test       L0060 ERROR|     time.sleep(self.params.sleep_length)
    15:52:54 test       L0060 ERROR|   File "$HOME/Code/avocado/avocado/job.py", line 127, in timeout_handler
    15:52:54 test       L0060 ERROR|     raise exceptions.TestTimeoutError(e_msg)
    15:52:54 test       L0060 ERROR| TestTimeoutError: Timeout reached waiting for sleeptest to end
    15:52:54 test       L0061 ERROR|
    15:52:54 test       L0400 ERROR| ERROR sleeptest.1 -> TestTimeoutError: Timeout reached waiting for sleeptest to end
    15:52:54 test       L0387 INFO |


If you pass that multiplex file to the runner multiplexer, this will register
a timeout of 3 seconds before Avocado ends the test forcefully by sending a
:class:`signal.SIGTERM` to the test, making it raise a
:class:`avocado.core.exceptions.TestTimeoutError`.

* Default params attribute. Consider the following example:

::

    import time

    from avocado import Test
    from avocado import main


    class TimeoutTest(Test):

        """
        Functional test for Avocado. Throw a TestTimeoutError.
        """
        default_params = {'timeout': 3.0,
                          'sleep_time': 5.0}

        def test(self):
            """
            This should throw a TestTimeoutError.
            """
            self.log.info('Sleeping for %.2f seconds (2 more than the timeout)',
                          self.params.sleep_time)
            time.sleep(self.params.sleep_time)


    if __name__ == "__main__":
        main()

This accomplishes a similar effect to the multiplex setup defined in there.

::

    $ avocado run timeouttest
    JOB ID    : d78498a54504b481192f2f9bca5ebb9bbb820b8a
    JOB LOG   : $HOME/avocado/job-results/job-2014-08-12T15.54-d78498a5/job.log
    JOB HTML  : $HOME/avocado/job-results/job-2014-08-12T15.54-d78498a5/html/results.html
    TESTS     : 1
     (1/1) timeouttest.1: ERROR (2.97 s)
    RESULTS    : PASS 0 | ERROR 1 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0
    TIME      : 2.97 s


::

    $ cat $HOME/avocado/job-results/job-2014-08-12T15.54-d78498a5/job.log
    15:54:28 test       L0143 INFO | START timeouttest.1
    15:54:28 test       L0144 DEBUG|
    15:54:28 test       L0145 DEBUG| Test log: $HOME/avocado/job-results/job-2014-08-12T15.54-d78498a5/timeouttest.1/test.log
    15:54:28 test       L0146 DEBUG| Test instance parameters:
    15:54:28 test       L0153 DEBUG|     id = timeouttest
    15:54:28 test       L0154 DEBUG|
    15:54:28 test       L0157 DEBUG| Default parameters:
    15:54:28 test       L0159 DEBUG|     sleep_time = 5.0
    15:54:28 test       L0159 DEBUG|     timeout = 3.0
    15:54:28 test       L0161 DEBUG|
    15:54:28 test       L0162 DEBUG| Test instance params override defaults whenever available
    15:54:28 test       L0163 DEBUG|
    15:54:28 test       L0169 INFO | Test timeout set. Will wait 3.00 s for PID 15759 to end
    15:54:28 test       L0170 INFO |
    15:54:28 timeouttes L0036 INFO | Sleeping for 5.00 seconds (2 more than the timeout)
    15:54:31 test       L0057 ERROR|
    15:54:31 test       L0060 ERROR| Traceback (most recent call last):
    15:54:31 test       L0060 ERROR|   File "$HOME/Code/avocado/tests/timeouttest.py", line 37, in action
    15:54:31 test       L0060 ERROR|     time.sleep(self.params.sleep_time)
    15:54:31 test       L0060 ERROR|   File "$HOME/Code/avocado/avocado/job.py", line 127, in timeout_handler
    15:54:31 test       L0060 ERROR|     raise exceptions.TestTimeoutError(e_msg)
    15:54:31 test       L0060 ERROR| TestTimeoutError: Timeout reached waiting for timeouttest to end
    15:54:31 test       L0061 ERROR|
    15:54:31 test       L0400 ERROR| ERROR timeouttest.1 -> TestTimeoutError: Timeout reached waiting for timeouttest to end
    15:54:31 test       L0387 INFO |


Test Tags
=========

The need may arise for more complex tests, that use more advanced Python features
such as inheritance. Due to the fact that Avocado uses a safe test introspection
method, that is more limited than actual loading of the test classes, Avocado
may need your help to identify those tests. For example, let's say you are
defining a new test class that inherits from the Avocado base test class and
putting it in ``mylibrary.py``::

    from avocado import Test


    class MyOwnDerivedTest(Test):
        def __init__(self, methodName='test', name=None, params=None,
                     base_logdir=None, tag=None, job=None, runner_queue=None):
            super(MyOwnDerivedTest, self).__init__(methodName, name, params,
                                                   base_logdir, tag, job,
                                                   runner_queue)
            self.log('Derived class example')


Then implement your actual test using that derived class, in ``mytest.py``::

    import mylibrary


    class MyTest(mylibrary.MyOwnDerivedTest):

        def test1(self):
            self.log('Testing something important')

        def test2(self):
            self.log('Testing something even more important')


If you try to list the tests in that file, this is what you'll get::

    scripts/avocado list mytest.py -V
    Type       Test
    NOT_A_TEST mytest.py

    ACCESS_DENIED: 0
    BROKEN_SYMLINK: 0
    EXTERNAL: 0
    FILTERED: 0
    INSTRUMENTED: 0
    MISSING: 0
    NOT_A_TEST: 1
    SIMPLE: 0
    VT: 0

You need to give avocado a little help by adding a docstring tag. That docstring
tag is ``:avocado: enable``. That tag tells the Avocado safe test detection
code to consider it as an avocado test, regardless of what the (admittedly simple)
detection code thinks of it. Let's see how that works out. Add the docstring,
as you can see the example below::

    import mylibrary


    class MyTest(mylibrary.MyOwnDerivedTest):
        """
        :avocado: enable
        """
        def test1(self):
            self.log('Testing something important')

        def test2(self):
            self.log('Testing something even more important')


Now, trying to list the tests on the ``mytest.py`` file again::

    scripts/avocado list mytest.py -V
    Type         Test
    INSTRUMENTED mytest.py:MyTest.test1
    INSTRUMENTED mytest.py:MyTest.test2

    ACCESS_DENIED: 0
    BROKEN_SYMLINK: 0
    EXTERNAL: 0
    FILTERED: 0
    INSTRUMENTED: 2
    MISSING: 0
    NOT_A_TEST: 0
    SIMPLE: 0
    VT: 0

You can also use the ``:avocado: disable`` tag, that works the opposite way:
Something looks like an Avocado test, but we force it to not be listed as one.

Environment Variables for Simple Tests
======================================

Avocado exports Avocado variables and multiplexed variables as BASH environment
to the running test. Those variables are interesting to simple tests, because
they can not make use of Avocado API directly with Python, like the native
tests can do and also they can modify the test parameters.

Here are the current variables that Avocado exports to the tests:

+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| Environemnt Variable    | Meaning                               | Example                                                                                             |
+=========================+=======================================+=====================================================================================================+
| AVOCADO_VERSION         | Version of Avocado test runner        | 0.12.0                                                                                              |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_BASEDIR    | Base directory of Avocado tests       | $HOME/Downloads/avocado-source/avocado                                                              |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_DATADIR    | Data directory for the test           | $AVOCADO_TEST_BASEDIR/my_test.sh.data                                                               |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_WORKDIR    | Work directory for the test           | /var/tmp/avocado_Bjr_rd/my_test.sh                                                                  |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_SRCDIR     | Source directory for the test         | /var/tmp/avocado_Bjr_rd/my-test.sh/src                                                              |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_LOGDIR     | Log directory for the test            | $HOME/logs/job-results/job-2014-09-16T14.38-ac332e6/test-results/$HOME/my_test.sh.1                 |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_LOGFILE    | Log file for the test                 | $HOME/logs/job-results/job-2014-09-16T14.38-ac332e6/test-results/$HOME/my_test.sh.1/debug.log       |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_OUTPUTDIR  | Output directory for the test         | $HOME/logs/job-results/job-2014-09-16T14.38-ac332e6/test-results/$HOME/my_test.sh.1/data            |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| AVOCADO_TEST_SYSINFODIR | The system information directory      | $HOME/logs/job-results/job-2014-09-16T14.38-ac332e6/test-results/$HOME/my_test.sh.1/sysinfo         |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+
| *                       | All variables from --multiplex-file   | TIMEOUT=60; IO_WORKERS=10; VM_BYTES=512M; ...                                                       |
+-------------------------+---------------------------------------+-----------------------------------------------------------------------------------------------------+


Simple Tests BASH extensions
============================

To enhance simple tests one can use supported set of libraries we created. The
only requirement is to use::

    PATH=$(avocado "exec-path"):$PATH

which injects path to Avocado utils into shell PATH. Take a look into
``avocado exec-path`` to see list of available functions and take a look at
``examples/tests/simplewarning.sh`` for inspiration.


Wrap Up
=======

We recommend you take a look at the example tests present in the
``examples/tests`` directory, that contains a few samples to take some
inspiration from. That directory, besides containing examples, is also used by
the Avocado self test suite to do functional testing of Avocado itself.

It is also recommended that you take a look at the :ref:`api-reference`.
for more possibilities.

.. [#f1] sleeptest is a functional test for Avocado. It's "old" because we
	 also have had such a test for `Autotest`_ for a long time.

.. _Autotest: http://autotest.github.io
.. _Class Names: https://www.python.org/dev/peps/pep-0008/
.. _PEP8 Function Names: https://www.python.org/dev/peps/pep-0008/#function-names