workload-automation/doc/source/revent.rst

.. _revent_files_creation:

revent
======

revent utility can be used to record and later play back a sequence of user
input events, such as key presses and touch screen taps. This is an alternative
to Android UI Automator for providing automation for workloads. ::


        usage:
                revent [record time file|replay file|info] [verbose]
                        record: stops after either return on stdin
                                or time (in seconds)
                                and stores in file
                        replay: replays eventlog from file
                        info:shows info about each event char device
                        any additional parameters make it verbose

Recording
---------

WA features a ``record`` command that will automatically deploy and start
revent on the target device::

    wa record
    INFO     Connecting to device...
    INFO     Press Enter when you are ready to record...
    [Pressed Enter]
    INFO     Press Enter when you have finished recording...
    [Pressed Enter]
    INFO     Pulling files from device

Once started, you will need to get the target device ready to record (e.g.
unlock screen, navigate menus and launch an app) then press ``ENTER``.
The recording has now started and button presses, taps, etc you perform on
the device will go into the .revent file. To stop the recording simply press
``ENTER`` again.

Once you have finished recording the revent file will be pulled from the device
to the current directory. It will be named ``{device_model}.revent``. When
recording revent files for a ``GameWorkload`` you can use the ``-s`` option to
add ``run`` or ``setup`` suffixes.

For more information run please read :ref:`record-command`


Replaying
---------

To replay a recorded file, run ``wa replay``, giving it the file you want to
replay::

        wa replay my_recording.revent

For more information run please read :ref:`replay-command`

Using revent With Workloads
---------------------------

Some workloads (pretty much all games) rely on recorded revents for their
execution. :class:`wlauto.common.GameWorkload`-derived workloads expect two
revent files -- one for performing the initial setup (navigating menus,
selecting game modes, etc), and one for the actual execution of the game.
Because revents are very device-specific\ [*]_, these two files would need to
be recorded for each device.

The files must be called ``<device name>.(setup|run).revent``, where
``<device name>`` is the name of your device (as defined by the ``name``
attribute of your device's class). WA will look for these files in two
places: ``<install dir>/wlauto/workloads/<workload name>/revent_files``
and ``~/.workload_automation/dependencies/<workload name>``. The first
location is primarily intended for revent files that come with WA (and if
you did a system-wide install, you'll need sudo to add files there), so it's
probably easier to use the second location for the files you record. Also,
if revent files for a workload exist in both locations, the files under
``~/.workload_automation/dependencies`` will be used in favor of those
installed with WA.

For example, if you wanted to run angrybirds workload on "Acme" device, you would
record the setup and run revent files using the method outlined in the section
above and then pull them for the devices into the following locations::

        ~/workload_automation/dependencies/angrybirds/Acme.setup.revent
        ~/workload_automation/dependencies/angrybirds/Acme.run.revent

(you may need to create the intermediate directories if they don't already
exist).

.. [*] It's not just about screen resolution -- the event codes may be different
       even if devices use the same screen.


revent vs. UiAutomator
----------------------

In general, Android UI Automator is the preferred way of automating user input
for workloads because, unlike revent, UI Automator does not depend on a
particular screen resolution, and so is more portable across different devices.
It also gives better control and can potentially be faster for ling UI
manipulations, as input events are scripted based on the available UI elements,
rather than generated by human input.

On the other hand, revent can be used to manipulate pretty much any workload,
where as UI Automator only works for Android UI elements (such as text boxes or
radio buttons), which makes the latter useless for things like games. Recording
revent sequence is also faster than writing automation code (on the other hand,
one would need maintain a different revent log for each screen resolution).


File format of revent
=====================

.. note:: All values below are little endian

Recording structure of revent
-----------------------------

revent recordings are made of of five parts:

 * A "magic" string of `REVENT` to help identify revent recordings.
 * A unsigned integer representing the revent file format version.
 * A signed integer that gives the number of devices in this recording.
 * A series of device paths, the number of which is given in the previous field.
   For more detail see `Device path structure`_ below.
 * An unlimited number of recorded events. For more detail see `Event Structure`_
   below.

::

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                             MAGIC                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          MAGIC cont.          |            Version            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Number of devices                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |             Device paths              +-+-+-+-+-+-+-+-+-+-+-+-+
    |                                       |                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                       |
    |                                                               |
    |                             Events                            |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Device path structure
----------------------

This part of an revent recording is used to store the paths to input devices used in the
recording. It consists of:

 * A signed integer giving the size of the following string.
 * A string, with a maximum length of 30, containing the path of an input device.

::

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Length of device path                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |                          Device path                          |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Event structure
---------------

The majority of an revent recording will be made up of the input events that were
recorded. There and be an unlimited number of these events in an revent file and they
are structured as follows:

 * A signed integer representing which device from the list of device paths
   this event is for (zero indexed). E.g. Device ID = 3 would be the 4th
   device in the list of device paths.
 * 32 bits of padding
 * A signed integer representing the number of seconds since "epoch" when the
   event was recorded.
 * A signed integer representing the microseconds part of the timestamp.
 * An unsigned integer representing the event type
 * An unsigned integer representing the event code
 * An unsigned integer representing the event value

For more information about the event type, code and value please read:
https://www.kernel.org/doc/Documentation/input/event-codes.txt

::

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                           Device ID                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                            PADDING                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Timestamp Seconds                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Timestamp Seconds cont.                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Timestamp Micoseconds                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Timestamp Micoseconds cont.                  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Event Type           |          Event Code           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Event Value                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Using state detection with revent
=================================

State detection can be used to verify that a workload is executing as expected.
This utility, if enabled, and if state definitions are available for the
particular workload, takes a screenshot after the setup and the run revent
sequence, matches the screenshot to a state and compares with the expected
state. A WorkloadError is raised if an unexpected state is encountered.

To enable state detection, make sure a valid state definition file and
templates exist for your workload and set the check_states parameter to True.

State definition directory
--------------------------

State and phase definitions should be placed in a directory of the following
structure inside the dependencies directory of each workload (along with
revent files etc):

   dependencies/
      <workload_name>/
         state_definitions/
            definition.yaml
            templates/
               <oneTemplate>.png
               <anotherTemplate>.png
               ...

definition.yaml file
--------------------

This defines each state of the workload and lists which templates are expected
to be found and how many are required to be detected for a conclusive match. It
also defines the expected state in each workload phase where a state detection
is run (currently those are setupComplete and runComplete).

Templates are picture elements to be matched in a screenshot. Each template
mentioned in the definition file should be placed as a file with the same name
and a .png extension inside the templates folder. Creating template png files
is as simple as taking a screenshot of the workload in a given state, cropping
out the relevant templates (eg. a button, label or other unique element that is
present in that state) and storing them in PNG format.

Please see the definition file for Angry Birds below as an example to
understand the format. Note that more than just two states (for the afterSetup
and afterRun phase) can be defined and this helps track the cause of errors in
case an unexpected state is encountered.

.. code-block:: python

    workload_name: angrybirds

    workload_states:
      - state_name: titleScreen
        templates:
          - play_button
          - logo
        matches: 2
      - state_name: worldSelection
        templates:
          - first_world_thumb
          - second_world_thumb
          - third_world_thumb
          - fourth_world_thumb
        matches: 3
      - state_name: level_selection
        templates:
          - locked_level
          - first_level
        matches: 2
      - state_name: gameplay
        templates:
          - pause_button
          - score_label_text
        matches: 2
      - state_name: pause_screen
        templates:
          - replay_button
          - menu_button
          - resume_button
          - help_button
        matches: 4
      - state_name: level_cleared_screen
        templates:
          - level_cleared_text
          - menu_button
          - replay_button
          - fast_forward_button
        matches: 4

    workload_phases:
      - phase_name: setup_complete
        expected_state: gameplay
      - phase_name: run_complete
        expected_state: level_cleared_screen