Testing the new design

To test the new design after making changes, use the Unit-tests. During development, it is useful to only run selected tests, although remember that all tests must pass before proposing the change as a review.

In each case, ensure that your local packages are up to date and rebase your local development branch against master if git pull fetches new commits. If your branch needed to be updated, always build and install your local packages.

lava-server

$ ./lava_server/manage test

lava-server has several components, see the contents of ci-run for the full list. Each component can be tested separately:

$ ./lava_server/manage test lava_scheduler_app

To run particular tests in a specific file, add e.g. test_device.py to the command:

$ ./lava_server/manage test lava_scheduler_app.tests.test_device

Note

the tests directory needs to be specified (instead of the test process discovering all tests) and the filename lacks the .py suffix.

Add the class name to run all tests within that class within the specified file.:

$ ./lava_server/manage test lava_scheduler_app.tests.test_device.TestTemplates

Add a specific test function to run only that one unit test:

$ ./lava_server/manage test lava_scheduler_app.tests.test_device.TestTemplates.test_x86_template

The same path can also be passed to ./ci-run:

$ ./ci-run lava_scheduler_app.tests.test_device.TestTemplates.test_x86_template

This adds the pep8 check before running the test(s).

Jinja2 templates

  1. All jinja2 templates in lava_scheduler_app/tests/device-types/ will be tested using a basic check in lava_scheduler_app.tests.test_device.DeviceTypeTest.test_device_type_templates for YAML syntax. This renders the template without a device dictionary and checks that the output is valid YAML. This test will fail with syntax errors in variables, jinja2 blocks, inheritance and whitespace indent errors.

  2. Add a new unit test to the TestTemplates class in the same unit test file when any jinja2 template fails to parse. Change the DEBUG setting to True to see the rendered output and use the Online YAML Parser to identify the problems with the YAML output. Once the basic validation passes, add an initial device dictionary, following the examples and identify specific values in the output which can be asserted.

  3. Compare the output of the template with a realistic device dictionary, using the unit test, with the test YAML used when developing the underlying support. If this is a fix for an existing template, you can generate the relevant output on the master branch and verify against the changes in the local branch.

  4. Completed templates need to be installed into /etc/lava-server/dispatcher-config/device-types/ before testjobs can be submitted through XML-RPC. The lava-master daemon does not need to be restarted, the next submitted testjob will use the modified template(s).

lava-dispatcher

$ python -m unittest discover lava_dispatcher/pipeline/

To run a single test, use the test class name as output by a failing test, without the call to discover:

$ python -m unittest lava_dispatcher.pipeline.test.test_basic.TestPipelineInit.test_pipeline_init

$ python -m unittest -v -c -f lava_dispatcher.pipeline.test.test_basic.TestPipelineInit.test_pipeline_init

The call references the path to the python module, the class and then the test function within that class. To run all tests in a class, omit the function. To run all tests in a file, omit the class and the function.

Sets of tests can also be executed from the ./ci-run script of lava-dispatcher as well:

$ ./ci-run --test-suite lava_dispatcher.pipeline.test.test_basic.TestPipelineInit.test_pipeline_init

Also, install the updated lava-dispatcher package and use it to inspect the output of the pipeline using the --validate switch to lava-dispatch:

$ sudo lava-dispatch --validate --target ./devices/kvm01.yaml ./sample_jobs/kvm.yaml --output-dir=/tmp/test

Note

The refactoring has changed the behaviour of target - the value must be a path to a YAML file, not a hostname. This is because the refactored dispatcher has no local configuration, so the master sends the entire device configuration to the dispatcher as a single YAML file.

See also

Unit-tests for information on running the full set of unit tests on lava-server and lava-dispatcher.

The structure of any one job will be the same each time it is run (subject to changes in the developing codebase). Each different job will have a different pipeline structure. Do not rely on any of the pipeline levels have any specific labels. When writing unit tests, only use checks based on isinstance or self.name. (The description and summary fields are subject to change to make the validation output easier to understand whereas self.name is a strict class-based label.)

Sample pipeline description output

(Actual output is subject to frequent change.)

!!python/object/apply:collections.OrderedDict
- - - device
   - parameters:
       actions:
         boot:
           prompts: ['linaro-test', 'root@debian:~#']
           command:
             amd64: {qemu_binary: qemu-system-x86_64}
           methods: [qemu]
           overrides: [boot_cmds, qemu_options]
           parameters:
             boot_cmds:
             - {root: /dev/sda1}
             - {console: 'ttyS0,115200'}
             machine: accel=kvm:tcg
             net: ['nic,model=virtio', user]
             qemu_options: [-nographic]
         deploy:
           methods: [image]
       architecture: amd64
       device_type: kvm
       hostname: kvm01
       memory: 512
       root_part: 1
 - - job
   - parameters: {action_timeout: 5m, device_type: kvm, job_name: kvm-pipeline, job_timeout: 15m,
       output_dir: /tmp/codehelp, priority: medium, target: kvm01, yaml_line: 3}
 - - '1'
   - content:
       description: deploy image using loopback mounts
       level: '1'
       name: deployimage
       parameters:
         deployment_data: &id001 {TESTER_PS1: 'linaro-test [rc=$(echo \$?)]# ', TESTER_PS1_INCLUDES_RC: true,
           TESTER_PS1_PATTERN: 'linaro-test \[rc=(\d+)\]# ', boot_cmds: boot_cmds,
           distro: debian, lava_test_dir: /lava-%s, lava_test_results_dir: /lava-%s,
           lava_test_results_part_attr: root_part, lava_test_sh_cmd: /bin/bash}
       summary: deploy image
       valid: true
       yaml_line: 12
     description: deploy image using loopback mounts
     summary: deploy image
 - - '1.1'
   - content:
       description: download with retry
       level: '1.1'
       max_retries: 5
       name: download_action
       parameters:
         deployment_data: *id001
       sleep: 1
       summary: download-retry
       valid: true
     description: download with retry
     summary: download-retry
 - - '1.2'
   - content:
       description: md5sum and sha256sum
       level: '1.2'
       name: checksum_action
       parameters:
         deployment_data: *id001
       summary: checksum
       valid: true
     description: md5sum and sha256sum
     summary: checksum
 - - '1.3'
   - content:
       description: mount with offset
       level: '1.3'
       name: mount_action
       parameters:
         deployment_data: *id001
       summary: mount loop
       valid: true
     description: mount with offset
     summary: mount loop
 - - 1.3.1
   - content:
       description: calculate offset of the image
       level: 1.3.1
       name: offset_action
       parameters:
         deployment_data: *id001
       summary: offset calculation
       valid: true
     description: calculate offset of the image
     summary: offset calculation
 - - 1.3.2
   - content:
       description: ensure a loop back mount operation is possible
       level: 1.3.2
       name: loop_check
       parameters:
         deployment_data: *id001
       summary: check available loop back support
       valid: true
     description: ensure a loop back mount operation is possible
     summary: check available loop back support
 - - 1.3.3
   - content:
       description: Mount using a loopback device and offset
       level: 1.3.3
       max_retries: 5
       name: loop_mount
       parameters:
         deployment_data: *id001
       retries: 10
       sleep: 10
       summary: loopback mount
       valid: true
     description: Mount using a loopback device and offset
     summary: loopback mount
 - - '1.4'
   - content:
       description: customise image during deployment
       level: '1.4'
       name: customise
       parameters:
         deployment_data: *id001
       summary: customise image
       valid: true
     description: customise image during deployment
     summary: customise image
 - - '1.5'
   - content:
       description: load test definitions into image
       level: '1.5'
       name: test-definition
       parameters:
         deployment_data: *id001
       summary: loading test definitions
       valid: true
     description: load test definitions into image
     summary: loading test definitions
 - - 1.5.1
   - content:
       description: apply git repository of tests to the test image
       level: 1.5.1
       max_retries: 5
       name: git-repo-action
       parameters:
         deployment_data: *id001
       sleep: 1
       summary: clone git test repo
       uuid: b32dd5ff-fb80-44df-90fb-5fbd5ab35fe5
       valid: true
       vcs_binary: /usr/bin/git
     description: apply git repository of tests to the test image
     summary: clone git test repo
 - - 1.5.2
   - content:
       description: apply git repository of tests to the test image
       level: 1.5.2
       max_retries: 5
       name: git-repo-action
       parameters:
         deployment_data: *id001
       sleep: 1
       summary: clone git test repo
       uuid: 200e83ef-bb74-429e-89c1-05a64a609213
       valid: true
       vcs_binary: /usr/bin/git
     description: apply git repository of tests to the test image
     summary: clone git test repo
 - - 1.5.3
   - content:
       description: overlay test support files onto image
       level: 1.5.3
       name: test-overlay
       parameters:
         deployment_data: *id001
       summary: applying LAVA test overlay
       valid: true
     description: overlay test support files onto image
     summary: applying LAVA test overlay
 - - '1.6'
   - content:
       default_fixupdict: {FAIL: fail, PASS: pass, SKIP: skip, UNKNOWN: unknown}
       default_pattern: (?P<test_case_id>.*-*)\s+:\s+(?P<result>(PASS|pass|FAIL|fail|SKIP|skip|UNKNOWN|unknown))
       description: add lava scripts during deployment for test shell use
       lava_test_dir: /usr/lib/python2.7/dist-packages/lava_dispatcher/lava_test_shell
       level: '1.6'
       name: lava-overlay
       parameters:
         deployment_data: *id001
       runner_dirs: [bin, tests, results]
       summary: overlay the lava support scripts
       valid: true
       xmod: 493
     description: add lava scripts during deployment for test shell use
     summary: overlay the lava support scripts
 - - '1.7'
   - content:
       description: unmount the test image at end of deployment
       level: '1.7'
       max_retries: 5
       name: umount
       parameters:
         deployment_data: *id001
       sleep: 1
       summary: unmount image
       valid: true
     description: unmount the test image at end of deployment
     summary: unmount image
 - - '2'
   - content:
       description: boot image using QEMU command line
       level: '2'
       name: boot_qemu_image
       parameters:
         parameters: {failure_retry: 2, media: tmpfs, method: kvm, yaml_line: 22}
       summary: boot QEMU image
       timeout: {duration: 30, name: boot_qemu_image}
       valid: true
       yaml_line: 22
     description: boot image using QEMU command line
     summary: boot QEMU image
 - - '2.1'
   - content:
       description: Wait for a shell
       level: '2.1'
       name: expect-shell-connection
       parameters:
         parameters: {failure_retry: 2, media: tmpfs, method: kvm, yaml_line: 22}
       summary: Expect a shell prompt
       valid: true
     description: Wait for a shell
     summary: Expect a shell prompt
 - - '3'
   - content:
       level: '3'
       name: test
       parameters:
         parameters:
           definitions:
           - {from: git, name: smoke-tests, path: ubuntu/smoke-tests-basic.yaml,
             repository: 'git://git.linaro.org/qa/test-definitions.git', yaml_line: 31}
           - {from: git, name: singlenode-basic, path: singlenode01.yaml, repository: 'git://git.linaro.org/people/neilwilliams/multinode-yaml.git',
             yaml_line: 39}
           failure_retry: 3
           name: kvm-basic-singlenode
           yaml_line: 27
       summary: test
       valid: true
     description: null
     summary: test
 - - '4'
   - content:
       level: '4'
       description: finish the process and cleanup
       name: finalize
       parameters:
         parameters: {}
       summary: finalize the job
       valid: true
     description: finish the process and cleanup
     summary: finalize the job

Provisos with the current codebase

The code can be executed:

$ sudo lava-dispatch --target kvm01 lava_dispatcher/pipeline/test/sample_jobs/kvm.yaml --output-dir=/tmp/test
  • During development, there may be images left mounted at the end of the run. Always check the output of mount.
  • Files in /tmp/test are not removed at the start or end of a job as these would eventually form part of the result bundle and would also be in a per-job temporary directory (created by the scheduler). To be certain of what logs were created by each run, clear the directory each time.

Compatibility with the old dispatcher LavaTestShell

The hacks and workarounds in the old LavaTestShell classes may need to be marked and retained until such time as either the new model replaces the old or the bug can be fixed in both models. Whereas the submission schema, log file structure and result bundle schema have thrown away any backwards compatibility, LavaTestShell will need to at least attempt to retain compatibility while improving the overall design and integrating the test shell operations into the new classes.

Current possible issues include:

  • testdef.yaml is hardcoded into lava-test-runner when this could be a parameter fed into the overlay from the VCS handlers.
  • Dependent test definitions had special handling because certain YAML files had to be retained when the overlay was taken from the dispatcher and installed onto the device. This approach leads to long delays and the need to use wget on the device to apply the test definition overlay as a separate operation during LavaTestShell. The new classes should be capable of creating a complete overlay prior to the device being booted which allows for the entire VCS repo to be retained. This may change behaviour.
  • If dependent test definitions use custom signal handlers, this may not work - it would depend on how the job parameters are handled by the new classes.

Logical actions

RetryAction subclassing

For a RetryAction to validate, the RetryAction subclass must be a wrapper class around a new internal_pipeline to allow the RetryAction.run() function to handle all of the retry functionality in one place.

An Action which needs to support failure_retry or which wants to use RetryAction support internally, needs a new class added which derives from RetryAction, sets a useful name, summary and description and defines a populate() function which creates the internal_pipeline. The Action with the customised run() function then gets added to the internal_pipeline of the RetryAction subclass - without changing the inheritance of the original Action.

Diagnostic subclasses

To add Diagnostics, add subclasses of DiagnosticAction to the list of supported Diagnostic classes in the Job class. Each subclass must define a trigger classmethod which is unique across all Diagnostic subclasses. (The trigger string is used as an index in a generator hash of classes.) Trigger strings are only used inside the Diagnostic class. If an Action catches a JobError or InfrastructureError exception and wants to allow a specific Diagnostic class to run, import the relevant Diagnostic subclass and add the trigger to the current job inside the exception handling of the Action:

try:
  self._run_command(cmd_list)
except JobError as exc:
  self.job.triggers.append(DiagnoseNetwork.trigger())
  raise JobError(exc)
return connection

Actions should only append triggers which are relevant to the JobError or InfrastructureError exception about to be raised inside an Action.run() function. Multiple triggers can be appended to a single exception. The exception itself is still raised (so that a RetryAction container will still operate).

Hint

A DownloadAction which fails to download a file could append a DiagnosticAction class which runs ifconfig or route just before raising a JobError containing the 404 message.

If the error to be diagnosed does not raise an exception, append the trigger in a conditional block and emit a JobError or InfrastructureError exception with a useful message.

Do not clear failed results of previous attempts when running a Diagnostic class - the fact that a Diagnostic was required is an indication that the job had some kind of problem.

Avoid overloading common Action classes with Diagnostics, add a new Action subclass and change specific Strategy classes (Deployment, Boot, Test) to use the new Action.

Avoid chaining Diagnostic classes - if a Diagnostic requires a command to exist, it must check that the command does exist. Raise a RuntimeError if a Strategy class leads to a Diagnostic failing to execute.

It is an error to add a Diagnostic class to any Pipeline. Pipeline Actions should be restricted to classes which have an effect on the Test itself, not simply reporting information.

Adjuvants - skipping actions and using helper actions

Sometimes, a particular test image will support the expected command but a subsequent image would need an alternative. Generally, the expectation is that the initial command should work, therefore the fallback or helper action should not be needed. The refactoring offers support for this situation using Adjuvants.

An Adjuvant is a helper action which exists in the normal pipeline but which is normally skipped, unless the preceding Action sets a key in the PipelineContext that the adjuvant is required. A successful operation of the adjuvant clears the key in the context.

One example is the reboot command. Normal user expectation is that a reboot command as root will successfully reboot the device but LAVA needs to be sure that a reboot actually does occur, so usually uses a hard reset PDU command after a timeout. The refactoring allows LAVA to distinguish between a job where the soft reboot worked and a job where the PDU command became necessary, without causing the test itself to fail simply because the job didn’t use a hard reset.

If the ResetDevice Action determines that a reboot happened (by matching a pexpect on the bootloader initialisation), then nothing happens and the Adjuvant action (in this case, HardResetDevice) is marked in the results as skipped. If the soft reboot fails, the ResetDevice Action marks this result as failed but also sets a key in the PipelineContext so that the HardResetDevice action then executes.

Unlike Diagnostics, Adjuvants are an integral part of the pipeline and show up in the verification output and the results, whether executed or not. An Adjuvant is not a simple retry, it is a different action, typically a more aggressive or forced action. In an ideal world, the adjuvant would never be required.

A similar situation exists with firmware upgrades. In this case, the adjuvant is skipped if the firmware does not need upgrading. The preceding Action would not be set as a failure in this situation but LAVA would still be able to identify which jobs updated the firmware and which did not.

Connections, Actions and the SignalDirector

Most deployment Action classes run without needing a Connection. Once a Connection is established, the Action may need to run commands over that Connection. At this point, the Action delegates the maintenance of the run function to the Connection pexpect. i.e. the Action.run() is blocked, waiting for Connection.run_command() (or similar) to return and the Connection needs to handle timeouts, signals and other interaction over the connection. This role is taken on by the internal SignalDirector within each Connection. Unlike the old model, Connections have their own directors which takes the multinode and LMP workload out of the singlenode operations.

Detecting power state

Devices on your desk can behave differently to those in the lab under full automation. Under automation, the hard_reset and power_off support means that the device is likely to be powered off when the first connection atttempt is made. On the desk, the device may spend more time powered on (even if the device is not running a usable system, for example the NFS location will be deleted when the previous job ends). So when writing connection classes and actions which initiate connections, check the power state of the device first.

  1. An Action initiating a connection needs to know if it should wait for a prompt. In the run function, add:

    if self.job.device.power_state not in ['on', 'off']:
        self.wait(connection)
    
  2. The next Action should be a ResetDevice action which understands the power state and determines whether to call the hard_reset commands or to attempt a soft reboot. In the populate function, ensure the correct ordering is in place:

    self.internal_pipeline.add_action(MenuConnect())
    self.internal_pipeline.add_action(ResetDevice())
    
  3. Warn if the device has no automation support in the validate function:

    if self.job.device.power_state in ['on', 'off']:
        # to enable power to a device, either power_on or hard_reset are needed.
        if self.job.device.power_command is '':
            self.errors = "Unable to power on or reset the device %s" % hostname
        if self.job.device.connect_command is '':
            self.errors = "Unable to connect to device %s" % hostname
    else:
        self.logger.warning("%s may need manual intervention to reboot" % hostname)
    

Power Commands

Some devices need a sequence of commands to change power state, some may require a sleep or similar delay. The power commands available in the device dictionary support two uses:

Simple string

This is the simplest form and is recommended for the majority of devices.

{% set hard_reset_command = '/usr/bin/pduclient --daemon tweetypie --hostname pdu --command reboot --port 08' %}

Simple list

It can be useful to have a short list of simple commands, e.g. during device integration. In the final file used in the device dictionary, the entire list must be on a single line.

{% set hard_reset_command = ['/usr/local/lab-scripts/snmp_pdu_control --hostname pdu14 --command reboot --port 5 --delay 20', '/usr/local/lab-scripts/eth008_control -a 10.0.9.2 -r 3 -s onoff'] %}

Note

Extending the list support to more than a simple list of sequential commands is not supported and there is also no support for shell operators like && or ||. Any device which needs something more complex must have custom scripts made available on the worker which can do all the conditionals and logic. A script will also make the device dictionary more readable.

Using connections

Construct your pipeline to use Actions in the order:

  • Prepare any overlays or commands or context data required later
  • Start a new connection
  • Issue the command which changes device state
  • Wait for the specified prompt on the new connection
  • Issue the commands desired over the new connection

Note

There may be several Retry actions necessary within these steps.

So, for a U-Boot operation, this results in a pipeline like:

  • UBootCommandOverlay - substitutes dynamic and device-specific data into the U-Boot command list specified in the device configuration.
  • ConnectDevice - establishes a serial connection to the device, as specified by the device configuration
  • UBootRetry - wraps the subsequent actions in a retry
  • UBootInterrupt - sets the Hit any key prompt in a new connection
  • ResetDevice - sends the reboot command to the device
  • ExpectShellSession - waits for the specified prompt to match
  • UBootCommandsAction - issues the commands to U-Boot

Starting a connection

Typically, a Connection is started by an Action within the Pipeline. The call to start a Connection must not return until all operations on that Connection are complete or the Pipeline determines that the Connection needs to be terminated.

Using debug logs

The refactored dispatcher has a different approach to logging:

  1. all logs are structured using YAML
  2. Actions log to discrete log files
  3. Results are logged for each action separately
  4. Log messages use appropriate YAML syntax.
  5. Messages received from the device are prefixed with target.
  6. YAML wrapping handled by the dedicated logger. Always use self.logger.<LEVEL> in an action.

Examples

Actual representation of the logs in the UI will change - these examples are the raw content of the output YAML.

- {debug: 'start: 1.4.2.3.7 test-install-overlay (max 300s)', ts: '2015-09-07T09:40:46.720450'}
- {debug: 'test-install-overlay duration: 0.02', ts: '2015-09-07T09:40:46.746036'}
- results:
    test-install-overlay: !!python/object/apply:collections.OrderedDict
    - - [success, a9b2300d-0864-4f9c-ba78-c2594b567fc5]
      - [skipped, a9b2300d-0864-4f9c-ba78-c2594b567fc5]
      - [duration, 0.024679899215698242]
      - [timeout, 300.0]
      - [level, 1.4.2.3.7]
- {debug: 'Received signal: <STARTTC> linux-linaro-ubuntu-pwd'}
- {target: ''}
- {target: ''}
- {target: ''}
- {target: ''}
- {debug: 'test shell timeout: 300 seconds'}
- {target: ''}
- {target: /lava-None/tests/0_smoke-tests}
- {target: <LAVA_SIGNAL_ENDTC linux-linaro-ubuntu-pwd>}
- {target: <LAVA_SIGNAL_TESTCASE TEST_CASE_ID=linux-linaro-ubuntu-pwd RESULT=pass>}
- {target: <LAVA_SIGNAL_STARTTC linux-linaro-ubuntu-uname>}
- {target: ''}
- {debug: 'Received signal: <ENDTC> linux-linaro-ubuntu-pwd'}
- {target: ''}
- {target: ''}
- {target: ''}
- {target: ''}
- {debug: 'test shell timeout: 300 seconds'}
- {debug: 'Received signal: <TESTCASE> TEST_CASE_ID=linux-linaro-ubuntu-pwd RESULT=pass'}
- {debug: 'res: {''test_case_id'': ''linux-linaro-ubuntu-pwd'', ''result'': ''pass''}
    data: {''test_case_id'': ''linux-linaro-ubuntu-pwd'', ''result'': ''pass''}'}
- results: {linux-linaro-ubuntu-pwd: pass, testsuite: smoke-tests-basic}
- {info: 'ok: lava_test_shell seems to have completed'}
- debug: {curl-http: pass, direct-install: pass, direct-update: pass, linux-linaro-ubuntu-ifconfig: pass,
    linux-linaro-ubuntu-ifconfig-dump: pass, linux-linaro-ubuntu-lsb_release: fail,
    linux-linaro-ubuntu-lscpu: pass, linux-linaro-ubuntu-netstat: pass, linux-linaro-ubuntu-pwd: pass,
    linux-linaro-ubuntu-route-dump-a: pass, linux-linaro-ubuntu-route-dump-b: pass,
    linux-linaro-ubuntu-route-ifconfig-up: pass, linux-linaro-ubuntu-route-ifconfig-up-lo: pass,
    linux-linaro-ubuntu-uname: pass, linux-linaro-ubuntu-vmstat: pass, ping-test: pass,
    remove-tgz: pass, tar-tgz: pass}
- {debug: 'lava-test-shell duration: 26.88', ts: '2015-09-07T09:43:14.065956'}

Debugging on the slave dispatcher

Pipeline jobs are sent to the slave dispatcher over ZMQ as fully formatted YAML files but are then deleted when the test job ends.

Equivalent files can be prepared using the lava-server manage device-dictionary review option to output the device configuration YAML. To re-run the job on the slave, pass this configuration as the --target option to lava-dispatch and specify a temporary --output-dir and the test job definition.

Note

MultiNode test jobs produce a specific test job for each node in the group. The original MultiNode definition cannot be executed by lava-dispatch on the command line and the job definition for a single node within a MultiNode group will also need editing before it can be run without reference to the other nodes.

Adding new classes

See also Mapping deployment actions to the python code:

The expectation is that new tasks for the dispatcher will be created by adding more specialist Actions and organising the existing Action classes into a new pipeline for the new task.

Adding new behaviour is a two step process:

  • always add a new Action, usually with an internal pipeline, to implement the new behaviour
  • add a new Strategy class which creates a suitable pipeline to use that Action.

A Strategy class may use conditionals to select between a number of top level Strategy Action classes, for example DeployImageAction is a top level Strategy Action class for the DeployImage strategy. If used, this conditional must only operate on job parameters and the device as the selection function is a classmethod.

A test Job will consist of multiple strategies, one for each of the listed actions in the YAML file. Typically, this may include a Deployment strategy, a Boot strategy and a Test strategy. Jobs can have multiple deployment, boot, or test actions. Strategies add top level Actions to the main pipeline in the order specified by the parser. For the parser to select the new strategy, the strategies.py module for the relevant type of action needs to import the new subclass. There should be no need to modify the parser itself.

A single top level Strategy Action implements a single strategy for the outer Pipeline. The use of Logical actions can provide sufficient complexity without adding conditionals to a single top level Strategy Action class. Image deployment actions will typically include a conditional to check if a Test action is required later so that the test definitions can be added to the overlay during deployment.

Re-use existing Action classes wherever these can be used without changes.

If two or more Action classes have very similar behaviour, re-factor to make a new base class for the common behaviour and retain the specialised classes.

Strategy selection via select() must only ever rely on the device and the job parameters. Add new parameters to the job to distinguish strategies, e.g. the boot method or deployment method.

  1. A Strategy class is simply a way to select which top level Action class is instantiated.
  2. A top level Action class creates an internal pipeline in populate()
    • Actions are added to the internal pipeline to do the rest of the work
  3. a top level Action will generally have a basic run() function which calls run_actions on the internal pipeline.

#. Ensure that the accepts routine can uniquely identify this strategy without interfering with other strategies. (Always add unit tests for new classes)

  1. Respect the existing classes - reuse wherever possible and keep all classes as pure as possible. There should be one class for each type of operation and no more, so to download a file onto the dispatcher use the DownloaderAction whether that is an image or a dtb. If the existing class does not do everything required, inherit from it and add functionality.
  2. Respect the directory structure - a strategies module should not need to import anything from outside that directory. Keep modules together with modules used in the same submission YAML stanza.
  3. Expose all configuration in the YAML, not python. There are FIXMEs in the code to remedy situations where this is not yet happening but avoid adding code which makes this problem worse. Extend the device or submission YAML structure if new values are needed.
  4. Take care with YAML structure. Always check your YAML changes in the online YAML parser as this often shows where a simple hyphen can dramatically change the complexity of the data.
  5. Cherry-pick existing classes alongside new classes to create new pipelines and keep all Action classes to a single operation.
  6. Code defensively:
    1. check that parameters exist in validation steps.
    2. call super() on the base class validate() in each Action.validate()
    3. handle missing data in the dynamic context
    4. use cleanup() and keep actions idempotent.

Always add unit tests for new classes

Wherever a new class is added, that new class can be tested - if only to be sure that it is correctly initialised and added to the pipeline at the correct level. Always create a new file in the tests directory for new functionality. All unit tests need to be in a file with the test_ prefix and add a new YAML file to the sample_jobs so that the strategies to select the new code can be tested. See Basics of the YAML format.

Often the simplest way to understand the available parameters and how new statements in the device configuration or job submission show up inside the classes is to use a unit test. To run a single unit-test, for example test_function in a class called TestExtra in a file called test_extra.py, use:

$ python -m unittest -v -c -f lava_dispatcher.pipeline.test.test_extra.TestExtra.test_function

Example python code:

import os
import unittest

class TestExtra(unittest.TestCase):  # pylint: disable=too-many-public-methods

   def test_function(self):
       print "Hello world"

Group similar operations

When using a connection to a device, group calls over that connection to calls which are expected to return within a consistent timeout for that class. If the final command from the class starts a longer running process, e.g. boot, set the connection prompt to look for a message which will be seen on that connection within a similar timeframe to all the other calls made by that class. This allows test writers to correctly choose the timeout to extend.

Add documentation

Add to the documentation when adding new classes which implement new dispatcher actions, parameters or behaviour.

Use syntax checkers during the refactoring

$ sudo apt install pylint
$ pylint -d line-too-long -d missing-docstring lava_dispatcher/pipeline/

Use class analysis tools

$ sudo apt install graphviz
$ pyreverse lava_dispatcher/pipeline/
$ dot -Tpng classes_No_Name.dot > classes.png

(Actual images can be very large.)

Use memory analysis tools

$ sudo apt install python-meliae

Add this python snippet to a unit test or part of the code of interest:

from meliae import scanner
scanner.dump_all_objects('filename.json')

Once the test has run, the specified filename will exist. To analyse the results, start up a python interactive shell in the same directory:

$ python
>>> from meliae import loader
>>> om = loader.load('filename.json')
loaded line 64869, 64870 objs,   8.7 /   8.7 MiB read in 0.9s
checked    64869 /    64870 collapsed     5136
set parents    59733 /    59734
collapsed in 0.4s
>>> s = om.summarize(); s

Note

The python interpreter, the setup.py configuration and other tools may allocate memory as part of the test, so the figures in the output may be larger than it would seem for a small test. A basic test may give a summary of 12Mb, total size. Figures above 100Mb should prompt a check on what is using the extra memory.

Pre-boot deployment manipulation

Note

These provisions are under development and are likely to change substantially. e.g. it may be possible to do a lot of these tasks using secondary media and secondary connections.

There are several situations where an environment needs to be setup in a contained and tested manner and then used for one or multiple LAVA test operations.

One solution is to use MultiNode and this works well when the device under test supports a secondary connection, e.g. ethernet.

MultiNode has requirements on a POSIX-type command line shell to be able to pass messages, e.g. busybox.

QEMU tests involve downloading a pre-built chroot based on a stable distribution release of a foreign architecture and running tests inside that chroot.

Android tests may involve setting up a VM or a configured chroot to expose USB devices while retaining the ability to use different versions of tools for different tests.