The extended testsuite only works with UID=0. It consists of the subdirectories
named "test/TEST-??-*", each of which contains a description of an OS image and
a test which consists of systemd units and scripts to execute in this image.
The same image is used for execution under `systemd-nspawn` and `qemu`.

To run the extended testsuite do the following:

$ ninja -C build  # Avoid building anything as root later
$ sudo test/run-integration-tests.sh
ninja: Entering directory `/home/zbyszek/src/systemd/build'
ninja: no work to do.
--x-- Running TEST-01-BASIC --x--
+ make -C TEST-01-BASIC clean setup run
make: Entering directory '/home/zbyszek/src/systemd/test/TEST-01-BASIC'
TEST-01-BASIC CLEANUP: Basic systemd setup
TEST-01-BASIC SETUP: Basic systemd setup
...
TEST-01-BASIC RUN: Basic systemd setup [OK]
make: Leaving directory '/home/zbyszek/src/systemd/test/TEST-01-BASIC'
--x-- Result of TEST-01-BASIC: 0 --x--
--x-- Running TEST-02-CRYPTSETUP --x--
+ make -C TEST-02-CRYPTSETUP clean setup run

If one of the tests fails, then $subdir/test.log contains the log file of
the test.

To run just one of the cases:

$ sudo make -C test/TEST-01-BASIC clean setup run

Specifying the build directory
==============================

If the build directory is not detected automatically, it can be specified
with BUILD_DIR=:

$ sudo BUILD_DIR=some-other-build/ test/run-integration-tests

or

$ sudo make -C test/TEST-01-BASIC BUILD_DIR=../../some-other-build/ ...

Note that in the second case, the path is relative to the test case directory.
An absolute path may also be used in both cases.

Testing installed binaries instead of built
===========================================

To run the extended testsuite using the systemd installed on the system instead
of the systemd from a build, use the NO_BUILD=1:

$ sudo NO_BUILD=1 test/run-integration-tests

Configuration variables
=======================

TEST_NO_QEMU=1
    Don't run tests under qemu

TEST_QEMU_ONLY=1
    Run only tests that require qemu

TEST_NO_NSPAWN=1
    Don't run tests under systemd-nspawn

TEST_PREFER_NSPAWN=1
    Run all tests that do not require qemu under systemd-nspawn

TEST_NO_KVM=1
    Disable qemu KVM auto-detection (may be necessary when you're trying to run the
    *vanilla* qemu and have both qemu and qemu-kvm installed)

TEST_NESTED_KVM=1
    Allow tests to run with nested KVM. By default, the testsuite disables
    nested KVM if the host machine already runs under KVM. Setting this
    variable disables such checks

QEMU_MEM=512M
    Configure amount of memory for qemu VMs (defaults to 512M)

QEMU_SMP=1
    Configure number of CPUs for qemu VMs (defaults to 1)

KERNEL_APPEND='...'
    Append additional parameters to the kernel command line

NSPAWN_ARGUMENTS='...'
    Specify additional arguments for systemd-nspawn

QEMU_TIMEOUT=infinity
    Set a timeout for tests under qemu (defaults to 1800 sec)

NSPAWN_TIMEOUT=infinity
    Set a timeout for tests under systemd-nspawn (defaults to 1800 sec)

INTERACTIVE_DEBUG=1
    Configure the machine to be more *user-friendly* for interactive debuggung
    (e.g. by setting a usable default terminal, suppressing the shutdown after
    the test, etc.)

TEST_MATCH_SUBTEST=subtest
    If the test makes use of `run_subtests` use this variable to provide
    a POSIX extended regex to run only subtests matching the expression

TEST_MATCH_TESTCASE=testcase
    Same as $TEST_MATCH_SUBTEST but for subtests that make use of `run_testcases`

The kernel and initrd can be specified with $KERNEL_BIN and $INITRD. (Fedora's
or Debian's default kernel path and initrd are used by default.)

A script will try to find your qemu binary. If you want to specify a different
one with $QEMU_BIN.

Debugging the qemu image
========================

If you want to log in the testsuite virtual machine, use INTERACTIVE_DEBUG=1
and log in as root:

$ sudo make -C test/TEST-01-BASIC INTERACTIVE_DEBUG=1 run

The root password is empty.

Ubuntu CI
=========

New PR submitted to the project are run through regression tests, and one set
of those is the 'autopkgtest' runs for several different architectures, called
'Ubuntu CI'.  Part of that testing is to run all these tests.  Sometimes these
tests are temporarily deny-listed from running in the 'autopkgtest' tests while
debugging a flaky test; that is done by creating a file in the test directory
named 'deny-list-ubuntu-ci', for example to prevent the TEST-01-BASIC test from
running in the 'autopkgtest' runs, create the file
'TEST-01-BASIC/deny-list-ubuntu-ci'.

The tests may be disabled only for specific archs, by creating a deny-list file
with the arch name at the end, e.g.
'TEST-01-BASIC/deny-list-ubuntu-ci-arm64' to disable the TEST-01-BASIC test
only on test runs for the 'arm64' architecture.

Note the arch naming is not from 'uname -m', it is Debian arch names:
https://wiki.debian.org/ArchitectureSpecificsMemo

For PRs that fix a currently deny-listed test, the PR should include removal
of the deny-list file.

In case a test fails, the full set of artifacts, including the journal of the
failed run, can be downloaded from the artifacts.tar.gz archive which will be
reachable in the same URL parent directory as the logs.gz that gets linked on
the Github CI status.

To add new dependencies or new binaries to the packages used during the tests,
a merge request can be sent to: https://salsa.debian.org/systemd-team/systemd
targeting the 'upstream-ci' branch.

The cloud-side infrastructure, that is hooked into the Github interface, is
located at:

https://git.launchpad.net/autopkgtest-cloud/

In case of infrastructure issues with this CI, things might go wrong in two
places:

- starting a job: this is done via a Github webhook, so check if the HTTP POST
  are failing on https://github.com/systemd/systemd/settings/hooks
- running a job: all currently running jobs are listed at
  https://autopkgtest.ubuntu.com/running#pkg-systemd-upstream in case the PR
  does not show the status for some reason
- reporting the job result: this is done on Canonical's cloud infrastructure,
  if jobs are started and running but no status is visible on the PR, then it is
  likely that reporting back is not working

For infrastructure help, reaching out to Canonical via the #ubuntu-devel channel
on libera.chat is an effective way to receive support in general.

Manually running a part of the Ubuntu CI test suite
===================================================

In some situations one may want/need to run one of the tests run by Ubuntu CI
locally for debugging purposes. For this, you need a machine (or a VM) with
the same Ubuntu release as is used by Ubuntu CI (Jammy ATTOW).

First of all, clone the Debian systemd repository and sync it with the code of
the PR (set by the $UPSTREAM_PULL_REQUEST env variable) you'd like to debug:

# git clone https://salsa.debian.org/systemd-team/systemd.git
# cd systemd
# git checkout upstream-ci
# TEST_UPSTREAM=1 UPSTREAM_PULL_REQUEST=12345 ./debian/extra/checkout-upstream

Now install necessary build & test dependencies:

## PPA with some newer Ubuntu packages required by upstream systemd
# add-apt-repository -y ppa:upstream-systemd-ci/systemd-ci
# apt build-dep -y systemd
# apt install -y autopkgtest debhelper genisoimage git qemu-system-x86

Build systemd deb packages with debug info:

# TEST_UPSTREAM=1 DEB_BUILD_OPTIONS="nocheck nostrip" dpkg-buildpackage -us -uc
# cd ..

Prepare a testbed image for autopkgtest (tweak the release as necessary):

# autopkgtest-buildvm-ubuntu-cloud --ram-size 1024 -v -a amd64 -r jammy

And finally run the autopkgtest itself:

# autopkgtest -o logs *.deb systemd/ \
              --timeout-factor=3 \
              --test-name=boot-and-services \
              --shell-fail \
              -- autopkgtest-virt-qemu --ram-size 2048 autopkgtest-jammy-amd64.img

where --test-name= is the name of the test you want to run/debug. The
--shell-fail option will pause the execution in case the test fails and shows
you the information how to connect to the testbed for further debugging.

Manually running CodeQL analysis
=====================================

This is mostly useful for debugging various CodeQL quirks.

Download the CodeQL Bundle from https://github.com/github/codeql-action/releases
and unpack it somewhere. From now the 'tutorial' assumes you have the `codeql`
binary from the unpacked archive in $PATH for brevity.

Switch to the systemd repository if not already:

$ cd <systemd-repo>

Create an initial CodeQL database:

$ CCACHE_DISABLE=1 codeql database create codeqldb --language=cpp -vvv

Disabling ccache is important, otherwise you might see CodeQL complaining:

No source code was seen and extracted to /home/mrc0mmand/repos/@ci-incubator/systemd/codeqldb.
This can occur if the specified build commands failed to compile or process any code.
 - Confirm that there is some source code for the specified language in the project.
 - For codebases written in Go, JavaScript, TypeScript, and Python, do not specify
   an explicit --command.
 - For other languages, the --command must specify a "clean" build which compiles
   all the source code files without reusing existing build artefacts.

If you want to run all queries systemd uses in CodeQL, run:

$ codeql database analyze codeqldb/ --format csv --output results.csv .github/codeql-custom.qls .github/codeql-queries/*.ql -vvv

Note: this will take a while.

If you're interested in a specific check, the easiest way (without hunting down
the specific CodeQL query file) is to create a custom query suite. For example:

$ cat >test.qls <<EOF
- queries: .
  from: codeql/cpp-queries
- include:
    id:
        - cpp/missing-return
EOF

And then execute it in the same way as above:

$ codeql database analyze codeqldb/ --format csv --output results.csv test.qls -vvv

More about query suites here: https://codeql.github.com/docs/codeql-cli/creating-codeql-query-suites/

The results are then located in the `results.csv` file as a comma separated
values list (obviously), which is the most human-friendly output format the
CodeQL utility provides (so far).

Code coverage
=============

We have a daily cron job in CentOS CI which runs all unit and integration tests,
collects coverage using gcov/lcov, and uploads the report to Coveralls[0]. In
order to collect the most accurate coverage information, some measures have
to be taken regarding sandboxing, namely:

 - ProtectSystem= and ProtectHome= need to be turned off
 - the $BUILD_DIR with necessary .gcno files needs to be present in the image
   and needs to be writable by all processes

The first point is relatively easy to handle and is handled automagically by
our test "framework" by creating necessary dropins.

Making the $BUILD_DIR accessible to _everything_ is slightly more complicated.
First, and foremost, the $BUILD_DIR has a POSIX ACL that makes it writable
to everyone. However, this is not enough in some cases, like for services
that use DynamicUser=yes, since that implies ProtectSystem=strict that can't
be turned off. A solution to this is to use ReadWritePaths=$BUILD_DIR, which
works for the majority of cases, but can't be turned on globally, since
ReadWritePaths= creates its own mount namespace which might break some
services. Hence, the ReadWritePaths=$BUILD_DIR is enabled for all services
with the `test-` prefix (i.e. test-foo.service or test-foo-bar.service), both
in the system and the user managers.

So, if you're considering writing an integration test that makes use
of DynamicUser=yes, or other sandboxing stuff that implies it, please prefix
the test unit (be it a static one or a transient one created via systemd-run),
with `test-`, unless the test unit needs to be able to install mount points
in the main mount namespace - in that case use IGNORE_MISSING_COVERAGE=yes
in the test definition (i.e. TEST-*-NAME/test.sh), which will skip the post-test
check for missing coverage for the respective test.

[0] https://coveralls.io/github/systemd/systemd
