LAVA Test Shell

The lava_test_shell action provides a way to employ a black-box style testing appoach with the target device. The test definition format is designed to be flexible, allowing many options on how to do things.

Quick start

A minimal test definition looks like this:

metadata:
  name: passfail
  format: "Lava-Test-Shell Test Definition 1.0"
  description: "A simple passfail test for demo."
  os:
    - ubuntu
    - openembedded
  devices:
    - origen
    - panda
  environment:
    - lava-test-shell

params:
  TEST_1: pass

run:
  steps:
    - echo "test-1: $TEST_1"
    - echo "test-2: fail"

parse:
  pattern: "(?P<test_case_id>.*-*):\\s+(?P<result>(pass|fail))"

Note

The parse pattern has similar quoting rules as Python, so \s must be escaped as \\s and similar.

Some of the parameters here (os, devices, environment) are optional in the metadata section. Others are mandatory (name, format, description).

Versioned test definitions

If your test definition is not part of a git or bzr repository then it is must include a version parameter in the metadata section like in the following example.

metadata:
  name: passfail
  format: "Lava-Test-Shell Test Definition 1.0"
  version: "1.0"
  description: "A simple passfail test for demo."
  os:
    - ubuntu
    - openembedded
  devices:
    - origen
    - panda
  environment:
    - lava-test-shell

How a lava test shell is run

A lava-test-shell is run by:

  • building the test definition into a shell script.

    Note

    This shell script will include set -e, so a failing step will abort the entire test run. If you need to specify a step that might fail, finish the command with || true to make that failure not abort the test run.

  • copying this script onto the device and arranging for it to be run when the device boots

  • booting the device and letting the test run

  • retrieving the output from the device and turning it into a test result

  • run subsequent test definitions, if any.

Writing a test for lava-test-shell

For the majority of cases, the above approach is the easiest thing to do: write shell code that outputs “test-case-id: result” for each test case you are interested in. See the Test Developer Guide:

A possible advantage of the parsing approach is that it means your test is easy to work on independently from LAVA: simply write a script that produces the right sort of output, and then provide a very small amount of glue to wire it up in LAVA. However, using the parsing option will mean writing potentially complicated regular expressions.

When you need it, there is also a more powerful, LAVA-specific, way of writing tests. When a test runs, $PATH is arranged so that some LAVA-specific utilities are available:

See also

MultiNode API

lava-test-case

lava-test-case records the results of a single test case. For example:

steps:
  - "lava-test-case simpletestcase --result pass"
  - "lava-test-case fail-test --shell false"

It has two forms. One takes arguments to describe the outcome of the test case. The other takes the shell command to run, and the exit code of this shell command is used to produce the test result.

Both forms take the name of the testcase as the first argument.

Specifying results directly

The first form takes these additional arguments:

  • --result $RESULT: $RESULT should be one of pass/fail/skip/unknown
  • --measurement $MEASUREMENT: A numerical measurement associated with the test result
  • --units $UNITS: The units of $MEASUREMENT

--result must always be specified. For example:

run:
  steps:
    - "lava-test-case simpletestcase --result pass"
    - "lava-test-case bottle-count --result pass --measurement 99 --units bottles"

If --measurement is used, --units must also be specified, even if the unit is just a count.

The most useful way to produce output for lava-test-case result is Writing custom scripts to support tests which allow preparation of LAVA results from other sources, complete with measurements. This involves calling lava-test-case from scripts executed by the YAML file:

#!/usr/bin/env python

from subprocess import call


def test_case():
    """
    Calculate something based on a test
    and return the data
    """
    return {"name": "test-rate", "result": "pass",
        "units": "Mb/s", "measurement": 4.23}


def main():
    data = test_case()
    call(
        ['lava-test-case',
         data['name'],
         '--result', data['result'],
         '--measurement', data['measurement'],
         '--units', data['units']])
    return 0

if __name__ == '__main__':
    main()

The custom scripts themselves can be called from a lava-test-case using the --shell command to test whether failures from the tests caused a subsequent failure in the custom script.

Using the exit status of a command

The second form of lava-test-case is indicated by the --shell argument, for example:

run:
  steps:
    - "lava-test-case fail-test --shell false"
    - "lava-test-case pass-test --shell true"

The result of a shell call will only be recorded as a pass or fail, dependent on the exit code of the command. The output of the command can, however, be parsed as a separate result if the command produces output suitable for the parser in the YAML:

run:
   steps:
   - lava-test-case echo2 --shell echo "test2b:" "fail"
parse:
   pattern: "(?P<test_case_id>.*-*):\\s+(?P<result>(pass|fail))"

This example generates two test results to indicate that the shell command executed correctly but that the result of that execution was a failure:

#. **echo2** - pass
#. **test2b** - fail

lava-test-case-attach

Caution

lava-test-case-attach is disabled in the V2 dispatcher as there is no submit stage and no bundle creation stage on the device.

lava-test-run-attach

Caution

lava-test-run-attach is disabled in the V2 dispatcher as there is no submit stage and no bundle creation stage on the device.

lava-background-process-start

This starts a process in the background, for example:

steps:
  - lava-background-process-start MEM --cmd "free -m | grep Mem | awk '{print $3}' >> /tmp/memusage"
  - lava-background-process-start CPU --cmd "grep 'cpu ' /proc/stat"
  - uname -a
  - lava-background-process-stop CPU
  - lava-background-process-stop MEM --attach /tmp/memusage text/plain --attach /proc/meminfo application/octet-stream

The arguments are:

  1. The name that is used to identify the process later in lava-background-process-stop
  2. The command line for the process to be run in the background

See Handling test attachments.

lava-background-process-stop

This stops a process previously started in the background using lava-background-process-start. The user can attach files to the test run if there is a need.

For example:

steps:
  - lava-background-process-start MEM --cmd "free -m | grep Mem | awk '{print $3}' >> /tmp/memusage"
  - lava-background-process-start CPU --cmd "grep 'cpu ' /proc/stat"
  - uname -a
  - lava-background-process-stop CPU
  - lava-background-process-stop MEM --attach /tmp/memusage text/plain --attach /proc/meminfo application/octet-stream

The arguments are:

  1. The name that was specified in lava-background-process-start
  2. (optional) An indication that you want to attach file(s) to the test run with specified mime type. See Handling test attachments.

lava-lxc-device-add

Within lava-test-shell there is a possibility that the device attached to the lxc container, gets re-enumerated i.e., disconnects and reconnects, in which case the lxc container loses its visibility to the device, hence making it unusable within the lxc container. This command adds or re-adds the device to the lxc container. In most cases this command is used along with lava-lxc-device-wait-add, which waits for an add event in udev, for the device to reappear after a disconnection and reconnection.

For example:

steps:
  - adb devices
  - adb reboot bootloader
  - lava-lxc-device-add
  - fastboot devices

lava-lxc-device-wait-add

This command waits for an add event of an USB device to reappear in udev after a disconnection and reconnection of the device. In most cases this command is used along with lava-lxc-device-add

For example:

steps:
  - adb start-server
  - adb wait-for-device
  - adb devices
  - adb root
  - lava-lxc-device-wait-add
  - lava-lxc-device-add
  - adb wait-for-device
  - adb devices

Handling test attachments

The V1 dispatcher support for test attachments depends on the deprecated bundle and bundle stream support. The scripts available in lava-test shell do not actually attach the requested files, just copy the files to a hard-coded directory where the bundle processing code expects to find data to put into the bundle. This relies on the device being booted into an environment with a working network connection - what was called the master image.

In the V2 pipeline dispatcher, master images and bundles have been removed. This puts the handling of attachments into the control of the test writer. An equivalent method would be to simply add another deploy and boot action to get the test device into an environment where the network connection is known to work, however the eventual location of the file needs to be managed by the test writer. An alternative method for text based data is simply to output the contents into the log file.

Handling Dependencies (Debian)

If your test requires some packages to be installed before its run it can express that in the install section with:

install:
    deps:
        - linux-libc-dev
        - build-essential

Adding Git/BZR Repositories

If your test needs code from a shared repository, the action can clone this data on your behalf with:

install:
    bzr-repos:
        - lp:lava-test
    git-repos:
        - git://git.linaro.org/people/davelong/lt_ti_lava.git

run:
    steps:
        - cd lt_ti_lava
        - echo "now in the git cloned directory"

git-repos

There are several options for customising git repository handling in the git-repos action, for example:

install:
    git-repos:
        - url: https://git.linaro.org/lava/lava-dispatcher.git
          skip_by_default: False
        - url: https://git.linaro.org/lava/lava-dispatcher.git
          destination:  lava-d-r
          branch:       release
        - url: https://git.linaro.org/lava/lava-dispatcher.git
          destination:  lava-d-s
          branch:       staging
  • url is the git repository URL.
  • skip_by_default (optional) accepts a True or False. Repositories can be skipped by default in the test definition YAML and enabled for particular jobs directly in the job submission YAML, and vice versa.
  • destination (optional) is the directory in which the git repository given in url should be cloned, to override normal git behaviour.
  • branch (optional) is the branch within the git repository given in url that should be checked out after cloning.

Using parameters in the job to update the definition

Parameters used in the test definition YAML can be controlled from the YAML job file. See the following YAML test definition to get an understanding of how it works.

Install Steps

Before the test shell code is executed, it will optionally do some install work if needed. For example if you needed to build some code from a git repo you could do:

install:
    git-repos:
        - git://git.linaro.org/people/davelong/lt_ti_lava.git

    steps:
        - cd lt_ti_lava
        - make

Note

The repo steps are done in the dispatcher itself. The install steps are run directly on the target.

Advanced Parsing

Warning

Parse patterns and fixup dictionaries are confusing and hard to debug. The syntax is Python and the support remains for compatibility with existing Lava Test Shell Definitions. With LAVA V2, it is recommended to move parsing into a custom script contained within the test definition repository. The script can simply call lava-test-case directly with the relevant options once the data is parsed. This has the advantage that the log output from LAVA can be tested directly as input for the script.

You may need to incorporate an existing test that doesn’t output results in in the required pass/fail/skip/unknown format required by LAVA. The parse section has a fixup mechanism that can help:

parse:
    pattern: "(?P<test_case_id>.*-*)\\s+:\\s+(?P<result>(PASS|FAIL))"
    fixupdict:
        PASS: pass
        FAIL: fail

Note

Pattern can be double-quoted or single quoted. If it’s double-quoted, special characters need to be escaped. Otherwise, no escaping is necessary.

Single quote example:

parse:
    pattern: '(?P<test_case_id>.*-*)\s+:\s+(?P<result>(PASS|FAIL))'
    fixupdict:
        PASS: pass
        FAIL: fail

Adding dependent test cases

If your test depends on other tests to be executed before you run the current test, the following definition will help:

test-case-deps:
  - git-repo: git://git.linaro.org/qa/test-definitions.git
    testdef: common/passfail.yaml
  - bzr-repo: lp:~stylesen/lava-dispatcher/sampletestdefs-bzr
    testdef: testdef.yaml
  - url: https://people.linaro.org/~senthil.kumaran/deps_sample.yaml

The test cases specified within the ‘test-case-deps’ section will be fetched from the given repositories/URLs and then executed in the same specified order. The valid possible repository or URL source keys that may be specified inside the ‘test-case-deps’ section are:

1. git-repo
2. bzr-repo
3. tar-repo
4. url

Circular dependencies

Caution

lava-test-shell does not take care of circular dependencies within test definitions.

As an example, if testA.yaml lists a dependency on testB.yaml in its test-case-deps section then that will cause testB.yaml to be loaded and run first. However, if testB.yaml also points to testA.yaml in its test-case-deps section, that will cause testA.yaml to be loaded and run. This is an obvious circular dependency; real loops may be much more subtle, running through multiple test definitions in a complex setup with many defined dependencies. Be careful to avoid this! The log for a case like this would show many attempts at loading test definition... until the job is failed due to timeout.