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Test Writing Guidelines

This document describes guidelines and is intended for anybody who wants to write or modify a test case. It's not a definitive guide and it's not, by any means, a substitute for common sense.

General Rules

1. Simplicity

It's worth keeping test cases as simple as possible.

2. Code duplication

Whenever you are about to copy a large part of the code from one test case to another, think if it is possible to move it to a library to reduce code duplication and the cost of maintenance.

3. Coding style

Use common sense and BE CONSISTENT.

If you are editing code, take a few minutes to look at the code around you and determine its style.

The point of having style guidelines is to have a common vocabulary of coding so people can concentrate on what you are saying, rather than on how you are saying it.

3.1 Shell coding style

When writing test cases in shell write in portable shell only.

You can either try to run the test cases on Debian which has '/bin/sh' pointing to 'dash' by default or install 'dash' on your favorite distribution and use it to run the tests.

Ref: Shell Style Guide

3.2 Python coding style

Please follow PEP 8 style guide whenever possible.

Ref: PEP 8 Easy-to-read version of PEP 8 available at pep8.org

4. Commenting code

Use useful comments in your program to explain:

  • assumptions
  • important decisions
  • important details
  • problems you're trying to solve
  • problems you're trying to overcome in your program, etc.

Code tells you how, comments should tell you why.

5. License

Code contributed to this repository should be licensed under GPLv2+ (GNU GPL version 2 or any later version).

Writing a test case

Linux

1. Structure

Tests are generally placed under 'linux/' directory. Everything that relates to the test goes under the same folder named with test case name.

Define 'linux/test-case-name/output' folder in test case to save test output and result. Using a dedicated folder is helpful to distinguish between test script and test output.

2. Installing dependencies

The same test case should work on Debian/Ubuntu, Fedora/CentOS and OE based distributions whenever possible. This can be achieved with install_deps() function. The following is a simple example. "${SKIP_INSTALL}" should be set to 'true' on distributions that do not supported install_deps(). In the unsupported case, if "${SKIP_INSTALL}" is 'true', install_deps() still will skip package installation.

Example 1:

install_deps "${pkgs}" "${SKIP_INSTALL}"

Package name may vary by distribution. In this case, you will need to handle package installation with separate lines. dist_name() function is designed to detect the distribution ID at running time so that you can define package name by distribution. Refer to the following example.

Example 2:

dist_name
case "${dist}" in
  debian|ubuntu) install_deps "lsb-release" "${SKIP_INSTALL}" ;;
  fedora|centos) install_deps "redhat-lsb-core" "${SKIP_INSTALL}" ;;
  *) warn_msg "Unsupported distro: ${dist}! Package installation skipped." ;;
esac

Except automated package installation, you may also need to download and install software manually. If you want to make these steps skippable, here is an example.

Example 3:

if [ "${SKIP_INSTALL}" = "true" ] || [ "${SKIP_INSTALL}" = "True" ]; then
    dist_name
    case "${dist}" in
        debian|ubuntu) install_deps "${pkgs}" ;;
        fedora|centos) install_deps "${pkgs}" ;;
        *) warn_msg "Unsupported distro: ${dist}! Package installation skipped." ;;
    esac

    # manually install steps.
    git clone "${repo}"
    cd "${dir}"
    ./configure && make install
fi

Hopefully, the above 3 examples cover most of the user cases. When writing test cases, in general:

  • Define 'SKIP_INSTALL' variable with 'false' as default.
  • Add parameter '-s <True|False>', so that user can modify 'SKIP_INSTALL'.
  • Try to use the above functions, and give unknown distributions more care.

3. Saving output

'test-case-name/output' directory is recommended to save test log and result files.

4. Parsing result

Saving parsed result in the same format is important for post process such as sending to LAVA. The following result format should be followed:

test-case-id pass/fail/skip
test-case-id pass/fail/skip measurement
test-case-id pass/fail/skip measurement units

'output/result.txt' file is recommended to save result.

We encourage test writers to use the functions defined in 'sh-test-lib' to format test result.

Print "test-case pass/fail" by checking exit code:

check_return "${test_case_id}"

Add a metric for performance test:

add_metic "${test-case-id}" "pass/fail/skip" "${measurement}" "${units}"

5. Running in LAVA

LAVA is the foundation of test automation in Linaro. It is able to handle image deployment and boot, and provides a test shell for test run. To run a test case in LAVA, a definition file in YAML format is required.

Bear in mind, do all the LAVA-specific steps in test definition file, and do not use any LAVA-specific steps in test script, otherwise you may lock yourself out of your own test case when LAVA isn't available or the board you want to test wasn't deployed in LAVA.

Test script should handle dependencies installation, test execution, result parsing and other work in a self-contained way, and produce result.txt file with a format that can be easily parsed and sent to LAVA. This is a more robust way. Test case works with/without LAVA and can be tested locally.

A general test definition file should contain the below keywords and steps:

metadata:
# Define parameters required by test case with default values.
params:
  SKIP_INSTALL: False
run:
  # A typical test run in LAVA requires the below steps.
  steps:
    # Enter the directory of the test case.
    - cd ./automated/linux/smoke/
    # Run the test.
    - ./smoke.sh -s "${SKIP_INSTALL}"
    # Send the results in result.txt to LAVA.
    - ../../utils/send-to-lava.sh ./output/result.txt

Android specific

The above test writing guidelines also apply to Android test cases. The major difference is that we run all Android test cases through adb shell. Compare with local run, adb and adb shell enable us to do more. And this model is well supported by LAVA V2 LXC protocol.

A typical Android test case can be written with the following steps:

# Check adb connect with initialize_adb funtion
initialize_adb
# Install binaries and scripts
detect_abi
install "../../bin/${abi}/busybox"
install "./device-script.sh"
# Run test script through adb shell.
adb -s "${SN}" shell device-script.sh
# Pull output from device for parsing.
pull_output "${DEVICE_OUTPUT}" "${HOST_OUTPUT}"

6. Using test-runner

Using test-runner to run tests locally

The tests can be run directly on the board, assuming you have installed basic tools such as git, gcc, ... test-runner is written in Python and requires pexpect and yaml modules to be installed as well. To run tests directly on the board, get a prompt and run:

git clone http://git.linaro.org/qa/test-definitions.git
cd test-definitions
source automated/bin/setenv.sh
test-runner -p plans/rpb_ee/rpb_ee_functional.yaml

By default the test output are stored in $HOME/output/, and the output folder can be configured with -o argument.

Using test-runner to run tests from host PC

It is also possible to run tests from a host PC if the board is available on the network. In that case test-runner will connect to the board over SSH, and you need to setup the board so that the host PC can connect to the board over SSH without any prompt (password less connection). To run from the host, run the following commands from the host command prompt:

git clone http://git.linaro.org/qa/test-definitions.git
cd test-definitions
source automated/bin/setenv.sh
test-runner -g root@ip -p plans/rpb_ee/rpb_ee_functional.yaml

Where root@ip is the credential to connect to the board over SSH.

By default the test output are stored in $HOME/output/root@ip, and the output folder can be configured with -o argument.

Running individual tests

Instead of running a test plan with -p argument, it is possible to run a single test only using -d argument.

Test output

At the end of the test run, the following artefact are available in the output folder:

  • result.csv and result.json which contain summary of test results (including test name, test case ID, test results such as pass, fail, skip, test measurement, if any, with the associated measurement unit, and the test argument used
  • For each test executed, there is a folder which contains the console output of the test run, stdout.log as well as all test scripts/data

Test Contribution Checklist

  • When applicable, check test cases with the following tools with line length rule relaxed.
    • shellcheck: Shell script analysis tool.
    • pycodestyle: check Python code against the style conventions in PEP 8.
    • php: check syntax with 'php -l file'.
  • Run test cases on local system without LAVA.
  • Optionally, run test cases in LAVA and provide job example.