+Autopkgtest - Defining tests for Debian packages
+================================================
+
+This document describes how the autopkgtest tester core (the program
+`adt-run`) interprets and executes tests found in Debian source
+packages.
+
+Overview
+--------
+
+The source package provides a test metadata file `debian/tests/control`.
+This is a file containing zero or more RFC822-style stanzas, along these
+lines:
+
+ Tests: fred bill bongo
+ Restrictions: needs-root breaks-testbed
+
+This example defines three tests, called `fred`, `bill` and `bongo`. The
+tests will be performed by executing `debian/tests/fred`,
+`debian/tests/bill`, etc. Each test program should, on success, exit
+with status 0 and print nothing to stderr; if a test exits nonzero, or
+prints to stderr, it is considered to have failed.
+
+The cwd of each test is guaranteed to be the root of the source package,
+which will have been unpacked but not built. *However* note that the
+tests must test the *installed* version of the program. Tests may not
+modify the source tree (and may not have write access to it).
+
+If the file to be executed has no execute bits set, `chmod a+x` is
+applied to it (this means that tests can be added in patches without the
+need for additional chmod; contrast this with debian/rules).
+
+During execution of the test, the environment variable `$ADTTMP` will
+point to a directory for the execution of this particular test, which
+starts empty and will be deleted afterwards (so there is no need for the
+test to clean up files left there).
+
+If tests want to create artifacts which are useful to attach to test
+results, such as additional log files or screenshots, they can put them
+into the directory specified by the `$ADT_ARTIFACTS` environment
+variable. When using the `--output-dir` option, they will be copied into
+`outputdir/artifacts/`.
+
+Tests must declare all applicable Restrictions - see below.
+
+Control fields
+--------------
+
+The fields which may appear in debian/tests/control stanzas are:
+
+- **Tests:** *name-of-test [name-of-another-test ...]*
+
+ This field names the tests which are defined by this stanza, and map to
+ executables/scripts in the test directory. All of the other fields in the
+ same stanza apply to all of the named tests. Either this field or
+ `Test-Command:` must be present.
+
+ Test names are separated by whitespace and should contain only characters
+ which are legal in package names. It is permitted, but not encouraged, to use
+ upper-case characters as well.
+
+- **Test-Command:** *shell command*
+
+ If your test only contains a shell command or two, or you want to re-use an
+ existing upstream test executable and just need to wrap it with some command
+ like `dbus-launch` or `env`, you can use this field to specify the shell
+ command directly. It will be run under `bash -e`. This is mutually exclusive
+ with the `Tests:` field.
+
+- **Restrictions:** *restriction-name [another-restriction-name ...]*
+
+ Declares some restrictions or problems with the tests defined in this
+ stanza. Depending on the test environment capabilities, user requests, and so
+ on, restrictions can cause tests to be skipped or can cause the test to be
+ run in a different manner. Tests which declare unknown restrictions will be
+ skipped. See below for the defined restrictions.
+
+- **Features:** *feature-name [another-feature-name ...]*
+
+ Declares some additional capabilities or good properties of the tests defined
+ in this stanza. Any unknown features declared will be completely ignored. See
+ below for the defined features.
+
+- **Depends:** *dpkg dependency field syntax*
+
+ Declares that the specified packages must be installed for the test to go
+ ahead. This supports all features of dpkg dependencies (see
+ <https://www.debian.org/doc/debian-policy/ch-relationships.html>), plus the
+ following extensions:
+
+ `@` stands for the package(s) generated by the source package containing the
+ tests; each dependency (strictly, or-clause, which may contain `|`s but not
+ commas) containing `@` is replicated once for each such binary package, with
+ the binary package name substituted for each `@` (but normally `@` should
+ occur only once and without a version restriction).
+
+ `@builddeps@` will be replaced by the package's `Build-Depends:`,
+ `Build-Depends-Indep:`, and `build-essential`. This is useful if you have
+ many build dependencies which are only necessary for running the test suite
+ and you don't want to replicate them in the test `Depends:`. However, please
+ use this sparingly, as this can easily lead to missing binary package
+ dependencies being overlooked if they get pulled in via build dependencies.
+
+ If no Depends field is present, `Depends: @` is assumed. Note that the source
+ tree's Build-Dependencies are *not* necessarily installed, and if you specify
+ any Depends, no binary packages from the source are installed unless
+ explicitly requested.
+
+- **Tests-Directory:** *path*
+
+ Replaces the path segment `debian/tests` in the filenames of the test
+ programs with `path`. I. e., the tests are run by executing
+ `built/source/tree/path/testname`. `path` must be a relative path and is
+ interpreted starting from the root of the built source tree.
+
+ This allows tests to live outside the debian/ metadata area, so that they can
+ more palatably be shared with non-Debian distributions.
+
+- **Classes:** *class-1, class-2, ...*
+
+ Most package tests should work in a minimal environment and are usually not
+ hardware specific. However, some packages like the kernel, X.org, or graphics
+ drivers should be tested on particular hardware, and also run on a set of
+ different platforms rather than just a single virtual testbeds.
+
+ This field can specify a list of abstract class names such as "desktop" or
+ "graphics-driver". Consumers of autopkgtest can then map these class names to
+ particular machines/platforms/policies. Unknown class names should be
+ ignored.
+
+ This is purely an informational field for autopkgtest itself and will be
+ ignored.
+
+Any unknown fields will cause the whole stanza to be skipped.
+
+Defined restrictions
+--------------------
+
+- **rw-build-tree**
+
+ The test(s) needs write access to the built source tree (so it may need to be
+ copied first). Even with this restriction, the test is not allowed to make
+ any change to the built source tree which (i) isn't cleaned up by
+ debian/rules clean, (ii) affects the future results of any test, or (iii)
+ affects binary packages produced by the build tree in the future.
+
+- **breaks-testbed**
+
+ The test, when run, is liable to break the testbed system. This includes
+ causing data loss, causing services that the machine is running to
+ malfunction, or permanently disabling services; it does not include causing
+ services on the machine to temporarily fail.
+
+ When this restriction is present the test will usually be skipped unless the
+ testbed's virtualisation arrangements are sufficiently powerful, or
+ alternatively if the user explicitly requests.
+
+- **needs-root**
+
+ The test script must be run as root.
+
+- **build-needed**
+
+ The tests need to be run from a built source tree. The test runner will build
+ the source tree (honouring the source package's build dependencies), before
+ running the tests. However, the tests are *not* entitled to assume that the
+ source package's build dependencies will be installed when the test is run.
+
+ Please use this considerately, as for large builds it unnecessarily builds
+ the entire project when you only need a tiny subset (like the tests/
+ subdirectory). It is often possible to run `make -C tests` instead, or copy
+ the test code to `$ADTTMP` and build it there with some custom commands. This
+ cuts down the load on the Continuous Integration servers and also makes tests
+ more robust as it prevents accidentally running them against the built source
+ tree instead of the installed packages.
+
+- **allow-stderr**
+
+ Output to stderr is not considered a failure. This is useful for tests which
+ write e. g. lots of logging to stderr.
+
+- **isolation-container**
+
+ The test wants to start services or open network TCP ports. This commonly
+ fails in a simple chroot/schroot, so tests need to be run in their own
+ container (e. g. adt-virt-lxc) or their own machine/VM (e. g. adt-virt-qemu
+ or adt-virt-null). When running the test in a virtualization server which
+ does not provide this (like adt-virt-schroot) it will be skipped.
+
+- **isolation-machine**
+
+ The test wants to interact with the kernel, reboot the machine, or other
+ things which fail in a simple schroot and even a container. Those tests need
+ to be run in their own machine/VM (e. g. adt-virt-qemu or
+ adt-virt-null). When running the test in a virtualization server which does
+ not provide this it will be skipped.
+
+- **needs-recommends**
+
+ Enable installation of recommended packages in apt for the test
+ dependencies. This does not affect build dependencies.
+
+Defined features
+----------------
+
+There are no currently defined Features.
+
+Source package header
+---------------------
+
+To allow test execution environments to discover packages which provide
+tests, their source packages should have a `Testsuite:` header
+containing `autopkgtest` (which is currently the only defined value).
+Multiple values get comma separated, as usual in control files.
+
+This tag is added automatically by dpkg-source version 1.17.11 or later.
+For earlier Debian/Ubuntu releases you need to set it manually in
+debian/control by adding
+
+ XS-Testsuite: autopkgtest
+
+in the `Source:` paragraph.
+
+Implicit test control file for known package types
+--------------------------------------------------
+
+There are groups of similarly-structured packages for which the contents
+of `debian/tests/control` would be mostly identical. For those packages,
+if `debian/tests/control` is absent, an implicit control file is
+assumed. Those packages do not have to provide anything else, although
+they should still include an appropriate source package header
+(`XS-Testsuite`) so that they can be discovered in the archive.
+
+### Ruby packages
+
+The source package must contain at least one of the following files:
+
+- `debian/ruby-test-files.yaml`
+- `debian/ruby-tests.rb`
+- `debian/ruby-tests.rake`
+
+Implied control file: :
+
+ Test-Command: gem2deb-test-runner --autopkgtest 2>&1
+ Depends: @, @builddeps@, gem2deb-test-runner
+
+*Note:* `gem2deb` will be filtered out of the `Depends:` field, as it is
+not needed to run the tests for installed packages.
+
+Packages should declare `Testsuite: autopkgtest-pkg-ruby` in
+`debian/control`.
+
+### Perl packages
+
+The source package must contain a `t/` directory and at least one of the
+following files:
+
+- `Makefile.PL`
+- `Build.PL`
+
+Implied control file: :
+
+ Test-Command: /usr/share/pkg-perl-autopkgtest/runner build-deps
+ Depends: @, @builddeps@, pkg-perl-autopkgtest
+
+ Test-Command: /usr/share/pkg-perl-autopkgtest/runner runtime-deps
+ Depends: @, pkg-perl-autopkgtest
+
+Packages should declare `Testsuite: autopkgtest-pkg-perl` in
+`debian/control`.
+
+Reboot during a test
+--------------------
+
+Some testbeds support rebooting; for those, the testbed will have an
+`autopkgtest-reboot` command which tests can call to cause a reboot.
+**Do not** use `reboot` and similar commands directly! They will cause
+testbeds like `null` or `schroot` to reboot the entire host, and even
+for `qemu` it will just cause the test to fail as there is no state
+keeping to resume a test at the right position after reboot.
+
+The particular steps for a rebooting tests are:
+
+- The test calls `autopkgtest-reboot my_mark` with a "mark"
+ identifier. `autopkgtest-reboot` will cause the test to terminate
+ (with `SIGKILL`).
+- `adt-run` backs up the current state of the test source tree and any
+ `$ADT_ARTIFACTS` that were created so far, reboots the testbed, and
+ restores the test source tree and artifacts.
+- The test gets run again, this time with a new environment variable
+ `$ADT_REBOOT_MARK` containing the argument to `autopkgtest-reboot`,
+ e. g. `my_mark`.
+- The test needs to check `$ADT_REBOOT_MARK` and jump to the
+ appropriate point. A nonexisting variable means "start from the
+ beginning".
+
+This example test will reboot the testbed two times in between:
+
+ #!/bin/sh -e
+ case "$ADT_REBOOT_MARK" in
+ "") echo "test beginning"; autopkgtest-reboot mark1 ;;
+ mark1) echo "test in mark1"; autopkgtest-reboot mark2 ;;
+ mark2) echo "test in mark2" ;;
+ esac
+ echo "test end"