114 lines
3.7 KiB
ReStructuredText
114 lines
3.7 KiB
ReStructuredText
|
.. SPDX-License-Identifier: GPL-2.0
|
|||
|
|
|
|||
|
|
=================================
|
|||
|
|
KUnit - Linux Kernel Unit Testing
|
|||
|
|
=================================
|
|||
|
|
|
|||
|
|
.. toctree::
|
|||
|
|
:maxdepth: 2
|
|||
|
|
:caption: Contents:
|
|||
|
|
|
|||
|
|
start
|
|||
|
|
architecture
|
|||
|
|
run_wrapper
|
|||
|
|
run_manual
|
|||
|
|
usage
|
|||
|
|
api/index
|
|||
|
|
style
|
|||
|
|
faq
|
|||
|
|
tips
|
|||
|
|
running_tips
|
|||
|
|
|
|||
|
|
This section details the kernel unit testing framework.
|
|||
|
|
|
|||
|
|
Introduction
|
|||
|
|
============
|
|||
|
|
|
|||
|
|
KUnit (Kernel unit testing framework) provides a common framework for
|
|||
|
|
unit tests within the Linux kernel. Using KUnit, you can define groups
|
|||
|
|
of test cases called test suites. The tests either run on kernel boot
|
|||
|
|
if built-in, or load as a module. KUnit automatically flags and reports
|
|||
|
|
failed test cases in the kernel log. The test results appear in
|
|||
|
|
:doc:`KTAP (Kernel - Test Anything Protocol) format</dev-tools/ktap>`.
|
|||
|
|
It is inspired by JUnit, Python’s unittest.mock, and GoogleTest/GoogleMock
|
|||
|
|
(C++ unit testing framework).
|
|||
|
|
|
|||
|
|
KUnit tests are part of the kernel, written in the C (programming)
|
|||
|
|
language, and test parts of the Kernel implementation (example: a C
|
|||
|
|
language function). Excluding build time, from invocation to
|
|||
|
|
completion, KUnit can run around 100 tests in less than 10 seconds.
|
|||
|
|
KUnit can test any kernel component, for example: file system, system
|
|||
|
|
calls, memory management, device drivers and so on.
|
|||
|
|
|
|||
|
|
KUnit follows the white-box testing approach. The test has access to
|
|||
|
|
internal system functionality. KUnit runs in kernel space and is not
|
|||
|
|
restricted to things exposed to user-space.
|
|||
|
|
|
|||
|
|
In addition, KUnit has kunit_tool, a script (``tools/testing/kunit/kunit.py``)
|
|||
|
|
that configures the Linux kernel, runs KUnit tests under QEMU or UML
|
|||
|
|
(:doc:`User Mode Linux </virt/uml/user_mode_linux_howto_v2>`),
|
|||
|
|
parses the test results and
|
|||
|
|
displays them in a user friendly manner.
|
|||
|
|
|
|||
|
|
Features
|
|||
|
|
--------
|
|||
|
|
|
|||
|
|
- Provides a framework for writing unit tests.
|
|||
|
|
- Runs tests on any kernel architecture.
|
|||
|
|
- Runs a test in milliseconds.
|
|||
|
|
|
|||
|
|
Prerequisites
|
|||
|
|
-------------
|
|||
|
|
|
|||
|
|
- Any Linux kernel compatible hardware.
|
|||
|
|
- For Kernel under test, Linux kernel version 5.5 or greater.
|
|||
|
|
|
|||
|
|
Unit Testing
|
|||
|
|
============
|
|||
|
|
|
|||
|
|
A unit test tests a single unit of code in isolation. A unit test is the finest
|
|||
|
|
granularity of testing and allows all possible code paths to be tested in the
|
|||
|
|
code under test. This is possible if the code under test is small and does not
|
|||
|
|
have any external dependencies outside of the test's control like hardware.
|
|||
|
|
|
|||
|
|
|
|||
|
|
Write Unit Tests
|
|||
|
|
----------------
|
|||
|
|
|
|||
|
|
To write good unit tests, there is a simple but powerful pattern:
|
|||
|
|
Arrange-Act-Assert. This is a great way to structure test cases and
|
|||
|
|
defines an order of operations.
|
|||
|
|
|
|||
|
|
- Arrange inputs and targets: At the start of the test, arrange the data
|
|||
|
|
that allows a function to work. Example: initialize a statement or
|
|||
|
|
object.
|
|||
|
|
- Act on the target behavior: Call your function/code under test.
|
|||
|
|
- Assert expected outcome: Verify that the result (or resulting state) is as
|
|||
|
|
expected.
|
|||
|
|
|
|||
|
|
Unit Testing Advantages
|
|||
|
|
-----------------------
|
|||
|
|
|
|||
|
|
- Increases testing speed and development in the long run.
|
|||
|
|
- Detects bugs at initial stage and therefore decreases bug fix cost
|
|||
|
|
compared to acceptance testing.
|
|||
|
|
- Improves code quality.
|
|||
|
|
- Encourages writing testable code.
|
|||
|
|
|
|||
|
|
Read also :ref:`kinds-of-tests`.
|
|||
|
|
|
|||
|
|
How do I use it?
|
|||
|
|
================
|
|||
|
|
|
|||
|
|
* Documentation/dev-tools/kunit/start.rst - for KUnit new users.
|
|||
|
|
* Documentation/dev-tools/kunit/architecture.rst - KUnit architecture.
|
|||
|
|
* Documentation/dev-tools/kunit/run_wrapper.rst - run kunit_tool.
|
|||
|
|
* Documentation/dev-tools/kunit/run_manual.rst - run tests without kunit_tool.
|
|||
|
|
* Documentation/dev-tools/kunit/usage.rst - write tests.
|
|||
|
|
* Documentation/dev-tools/kunit/tips.rst - best practices with
|
|||
|
|
examples.
|
|||
|
|
* Documentation/dev-tools/kunit/api/index.rst - KUnit APIs
|
|||
|
|
used for testing.
|
|||
|
|
* Documentation/dev-tools/kunit/faq.rst - KUnit common questions and
|
|||
|
|
answers.
|