[PATCH v18 00/19] kunit: introduce KUnit, the Linux kernel unit testing framework

Brendan Higgins
2019-09-23T09:04:57Z

## TL;DR

This revision addresses comments from Linus[1] and Randy[2], by moving
top level `kunit/` directory to `lib/kunit/` and likewise moves top
level Kconfig entry under lib/Kconfig.debug, so the KUnit submenu now
shows up under the "Kernel Hacking" menu.

As a consequence of this, I rewrote patch 06/18 (kbuild: enable building
KUnit) - now 06/19 (lib: enable building KUnit in lib/), and now needs
to be re-acked/reviewed.

## Background

This patch set proposes KUnit, a lightweight unit testing and mocking
framework for the Linux kernel.

Unlike Autotest and kselftest, KUnit is a true unit testing framework;
it does not require installing the kernel on a test machine or in a VM
(however, KUnit still allows you to run tests on test machines or in VMs
if you want[3]) and does not require tests to be written in userspace
running on a host kernel. Additionally, KUnit is fast: From invocation
to completion KUnit can run several dozen tests in about a second.
Currently, the entire KUnit test suite for KUnit runs in under a second
from the initial invocation (build time excluded).

KUnit is heavily inspired by JUnit, Python's unittest.mock, and
Googletest/Googlemock for C++. KUnit provides facilities for defining
unit test cases, grouping related test cases into test suites, providing
common infrastructure for running tests, mocking, spying, and much more.

### What's so special about unit testing?

A unit test is supposed to test a single unit of code in isolation,
hence the name. There should be no dependencies outside the control of
the test; this means no external dependencies, which makes tests orders
of magnitudes faster. Likewise, since there are no external dependencies,
there are no hoops to jump through to run the tests. Additionally, this
makes unit tests deterministic: a failing unit test always indicates a
problem. Finally, because unit tests necessarily have finer granularity,
they are able to test all code paths easily solving the classic problem
of difficulty in exercising error handling code.

### Is KUnit trying to replace other testing frameworks for the kernel?

No. Most existing tests for the Linux kernel are end-to-end tests, which
have their place. A well tested system has lots of unit tests, a
reasonable number of integration tests, and some end-to-end tests. KUnit
is just trying to address the unit test space which is currently not
being addressed.

### More information on KUnit

There is a bunch of documentation near the end of this patch set that
describes how to use KUnit and best practices for writing unit tests.
For convenience I am hosting the compiled docs here[4].

Additionally for convenience, I have applied these patches to a
branch[5]. The repo may be cloned with:
git clone https://kunit.googlesource.com/linux
This patchset is on the kunit/initial/v5.3/v18 branch.

## History since v15

### v18

- Addrssed comments on 07/19 (kunit: test: add initial tests) from
Randy Dunlap by removing redundant dependencies from Kconfig entries.

### v17

- Addressed comments on 06/19 (lib: enable building KUnit in lib/) from
Stephen Boyd by moving KUnit submenu ahead of Runtime Testing
submenu.

### v16

- Addressed comments from Linus Torvalds by moving all kunit/ paths to
lib/kunit/.
- Addressed comments by Randy Dunlap by moving KUnit Kconfig under
lib/Kconfig.debug so the KUnit submenu shows up under the "Kernel
Hacking" menu.

[1] https://www.lkml.org/lkml/2019/9/20/696
[2] https://www.lkml.org/lkml/2019/9/20/738
[3] https://google.github.io/kunit-docs/third_party/kernel/docs/usage.html#kunit-on-non-uml-architectures
[4] https://google.github.io/kunit-docs/third_party/kernel/docs/
[5] https://kunit.googlesource.com/linux/+/kunit/initial/v5.3/v18

---
Avinash Kondareddy (1):
kunit: test: add tests for KUnit managed resources

Brendan Higgins (16):
kunit: test: add KUnit test runner core
kunit: test: add test resource management API
kunit: test: add string_stream a std::stream like string builder
kunit: test: add assertion printing library
kunit: test: add the concept of expectations
lib: enable building KUnit in lib/
kunit: test: add initial tests
objtool: add kunit_try_catch_throw to the noreturn list
kunit: test: add support for test abort
kunit: test: add tests for kunit test abort
kunit: test: add the concept of assertions
kunit: defconfig: add defconfigs for building KUnit tests
Documentation: kunit: add documentation for KUnit
MAINTAINERS: add entry for KUnit the unit testing framework
MAINTAINERS: add proc sysctl KUnit test to PROC SYSCTL section
kunit: fix failure to build without printk

Felix Guo (1):
kunit: tool: add Python wrappers for running KUnit tests

Iurii Zaikin (1):
kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec()

Documentation/dev-tools/index.rst | 1 +
Documentation/dev-tools/kunit/api/index.rst | 16 +
Documentation/dev-tools/kunit/api/test.rst | 11 +
Documentation/dev-tools/kunit/faq.rst | 62 +
Documentation/dev-tools/kunit/index.rst | 79 +
Documentation/dev-tools/kunit/start.rst | 180 ++
Documentation/dev-tools/kunit/usage.rst | 576 +++++++
MAINTAINERS | 13 +
arch/um/configs/kunit_defconfig | 3 +
include/kunit/assert.h | 356 ++++
include/kunit/string-stream.h | 51 +
include/kunit/test.h | 1490 +++++++++++++++++
include/kunit/try-catch.h | 75 +
kernel/Makefile | 2 +
kernel/sysctl-test.c | 392 +++++
lib/Kconfig.debug | 13 +
lib/Makefile | 2 +
lib/kunit/Kconfig | 36 +
lib/kunit/Makefile | 9 +
lib/kunit/assert.c | 141 ++
lib/kunit/example-test.c | 88 +
lib/kunit/string-stream-test.c | 52 +
lib/kunit/string-stream.c | 217 +++
lib/kunit/test-test.c | 331 ++++
lib/kunit/test.c | 478 ++++++
lib/kunit/try-catch.c | 118 ++
tools/objtool/check.c | 1 +
tools/testing/kunit/.gitignore | 3 +
tools/testing/kunit/configs/all_tests.config | 3 +
tools/testing/kunit/kunit.py | 136 ++
tools/testing/kunit/kunit_config.py | 66 +
tools/testing/kunit/kunit_kernel.py | 149 ++
tools/testing/kunit/kunit_parser.py | 310 ++++
tools/testing/kunit/kunit_tool_test.py | 206 +++
.../test_is_test_passed-all_passed.log | 32 +
.../test_data/test_is_test_passed-crash.log | 69 +
.../test_data/test_is_test_passed-failure.log | 36 +
.../test_is_test_passed-no_tests_run.log | 75 +
.../test_output_isolated_correctly.log | 106 ++
.../test_data/test_read_from_file.kconfig | 17 +
40 files changed, 6001 insertions(+)
create mode 100644 Documentation/dev-tools/kunit/api/index.rst
create mode 100644 Documentation/dev-tools/kunit/api/test.rst
create mode 100644 Documentation/dev-tools/kunit/faq.rst
create mode 100644 Documentation/dev-tools/kunit/index.rst
create mode 100644 Documentation/dev-tools/kunit/start.rst
create mode 100644 Documentation/dev-tools/kunit/usage.rst
create mode 100644 arch/um/configs/kunit_defconfig
create mode 100644 include/kunit/assert.h
create mode 100644 include/kunit/string-stream.h
create mode 100644 include/kunit/test.h
create mode 100644 include/kunit/try-catch.h
create mode 100644 kernel/sysctl-test.c
create mode 100644 lib/kunit/Kconfig
create mode 100644 lib/kunit/Makefile
create mode 100644 lib/kunit/assert.c
create mode 100644 lib/kunit/example-test.c
create mode 100644 lib/kunit/string-stream-test.c
create mode 100644 lib/kunit/string-stream.c
create mode 100644 lib/kunit/test-test.c
create mode 100644 lib/kunit/test.c
create mode 100644 lib/kunit/try-catch.c
create mode 100644 tools/testing/kunit/.gitignore
create mode 100644 tools/testing/kunit/configs/all_tests.config
create mode 100755 tools/testing/kunit/kunit.py
create mode 100644 tools/testing/kunit/kunit_config.py
create mode 100644 tools/testing/kunit/kunit_kernel.py
create mode 100644 tools/testing/kunit/kunit_parser.py
create mode 100755 tools/testing/kunit/kunit_tool_test.py
create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-all_passed.log
create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-crash.log
create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-failure.log
create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-no_tests_run.log
create mode 100644 tools/testing/kunit/test_data/test_output_isolated_correctly.log
create mode 100644 tools/testing/kunit/test_data/test_read_from_file.kconfig

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2.23.0.351.gc4317032e6-goog