NAME¶
Lintian::Tutorial::WritingTests -- Short tutorial on writing tests
SYNOPSIS¶
This document attempts to be a short / quick tutorial to the Lintian test suite
from a test-writer's perspective. As such, it will only cover the standard
type of tests (from the "tests" suite).
The guide will involve writing a test for the "deb/pkg-check" check,
which was documented in the Lintian::Tutorial::WritingChecks tutorial.
For running tests, please see Lintian::Tutorial::TestSuite instead.
DESCRIPTION¶
The Lintian test suite is divided into several parts. These are:
- -
- scripts
Small (Perl) "prove" tests. These assert that code style, data
files and/or self-contained code units (i.e. unit tests) work as intended.
They are not used for testing Lintian tags.
- -
- changes / debs / source
These suites are small test suites that test some particular tags for
.changes, .deb or .dsc files. Typically, you will
find the more exotic tags here, which require some special fiddling and
cannot be built by a "standard" dh7 + dpkg build.
- -
- tests
This suite is the standard test suite for testing Lintian tags.
With this in mind, let us move on to the scope.
Scope of the tutorial¶
The "tests" suite alone is fairly complex on its own. To keep things
simple, the tutorial will limit itself to creating a "native"
package with no special requirements in the "tests" suite.
In particular, note that the tags
must not be
pedantic for this to
work. If you followed the check writing tutorial and made the tags pedantic,
please change them into "I", "W" or "E" tags.
Once the basics are covered, you should be better equipped to deal with the
other ("tag testing") suites or using other features of the
"tests" suite (e.g. pedantic tags).
The design of the Lintian test suite¶
The basic design of the Lintian test suite can be summed up as
less is
more. The Debian build system is changing all the time (albeit, slowly)
and sometimes it deprecates or breaks existing features.
With over 400 tests all featuring the same basic parts, the test suite features
several tricks to keep up with the pace. It uses "skeletons"
(template) directories to seed the package structures and template files to
fill in the basic files (e.g. "debian/control" and
"debian/changelog").
This means that when a new standards-version comes along, debhelper deprecates a
feature or (more likely) Lintian adds a new tag, the majority of the tests can
quickly be adapted with only a minor effort.
Since pedantic tags tend to require additional effort to avoid, most Lintian
tests do
not run with pedantic tags enabled.
The basics of a "native" package in the "tests" suite¶
For starters, you need 2 files and 1 directory, which will be placed in
t/tests/<test-name>.
The desc file (mandatory)
This is the test description file. It is a deb822 file (i.e. same syntax as
debian/control), which contains a number of fields.
Let's start with the following template:
Testname: pkg-deb-check-general
Version: 1.0
Description: General test of the pkg/deb-check check
Test-For:
missing-multi-arch-field
missing-pre-depends-on-multiarch-support
This defines the name of the test, its sequence number (i.e. how early it should
be run), the version of the
generated package, a description and the
tags you intend to test for.
In case you were wondering why "invalid-multi-arch-field" is not
listed, then it is because dpkg will not allow us to use an invalid Multi-Arch
value. Therefore, that particular tag would have to be tested in the
"debs" suite instead.
Note that the value of the Testname field (as Source field), Version field and
Description field (as the synopsis)
will be used in the package. As
such, they must obey the normal requirements for these purposes.
Please keep the following conventions in mind:
- -
- The Testname should be "<check-name>-<test-name>"
Note that regular Lintian checks do not have a "/", so the
naming convention works slightly better there.
- -
- The Version should always be "1.0" unless the test requires
anything else.
For non-native packages, the default would be "1.0-1".
The "tags" file (mandatory, but may be empty)
This file contains the
sorted "expected" output of lintian.
Assuming all of the tags are "I" tags, the file should look
something like:
I: pkg-deb-check-general-missing-ma: missing-multi-arch-field
I: pkg-deb-check-general-missing-pred: missing-pre-depends-on-multiarch-support
The "debian/" directory (optional, but usually needed)
The unpacked debian package in its full glory. Note that this means that the
(e.g.)
debian/rules file would be
t/tests/<test-name>/debian/debian/rules (note the double
"debian/").
The directory is seeded from
t/templates/tests/<skeleton>/, where
skeleton is the value of the "Skeleton" field from the
"desc" file.
For this test, you only need a specialized control file. This file could look
something like:
Source: {$source}
Priority: extra
Section: {$section}
Maintainer: {$author}
Standards-Version: {$standards_version}
Build-Depends: {$build_depends}
Package: {$source}-missing-ma
Architecture: {$architecture}
Depends: $\{shlibs:Depends\}, $\{misc:Depends\}
Description: {$description} (invalid)
This is a test package designed to exercise some feature or tag of
Lintian. It is part of the Lintian test suite and may do very odd
things. It should not be installed like a regular package. It may
be an empty package.
.
Missing M-A field.
Package: {$source}-missing-pred
Architecture: any
Depends: $\{shlibs:Depends\}, $\{misc:Depends\}
Multi-arch: same
Description: {$description} (pre-depends)
This is a test package designed to exercise some feature or tag of
Lintian. It is part of the Lintian test suite and may do very odd
things. It should not be installed like a regular package. It may
be an empty package.
.
Missing Pre-Depends.
Running the test
At this point, the test is in fact ready to be executed. It can be run by using:
$ debian/rules runtests onlyrun=pkg-deb-check-general
OR
$ t/runtests --dump-logs t debian/test-out pkg-deb-check-general
However, it will not emit the correct tags unless pkg/deb-check is part of the
debian/main lintian profile. If your check is a part of a different profile,
add the "Profile: <name>" field to the "desc" file.
With this, the tutorial is over. Below you will find some more resources that
may be useful to your future test writing work.
REFERENCES / APPENDIX¶
A step-by-step guide of how a test case works¶
Basically, the tag-testing test cases all involve building a package and running
lintian on the result. The "tests" suite does a full build with
dpkg-buildpackage, the other suites "hand-craft" only the type of
artifacts they are named after (e.g. "source" produces only source
packages).
A test in the "tests" suite
The basic process of a lintian test in the "tests" suite.
- 1.
- Copy the "upstream" skeleton dir into the build dir (non-native
only)
- 2.
- Copy the "upstream" dir from the test into the build dir (if
present, non-native only)
- 3.
- Run the "pre_upstream" hook (if present, non-native only)
- 4.
- Assemble the upstream tarball (non-native only)
- 5.
- Copy the "debian" skeleton dir into the build dir
- 6.
- Copy the "debian" directory from the test into the build dir (if
present)
- 7.
- Create debian/control and debian/changelog from
"<file>.in" if they do not exist.
- 8.
- Create an empty watch file (if missing, non-native only)
- 9.
- Run the "pre_build" hook (if present)
- 10.
- Run dpkg-buildpackage
- 11.
- Run lintian on the build result
- 12.
- Run the "post_test" hook (if present)
- 13.
- Run the "test_calibration" hook (if present), which may produce
a new "expected output file".
- 14.
- Compare the result with the expected output.
Note that the majority of the steps are conditional on native/non-native
packages or presence of hooks.
A test in the "debs" and the "source" suite
The "debs" and the "source" suite share the same basic
steps, which are:
- 1.
- Copy the skeleton dir into the build dir
- 2.
- Copy the test directory files into the build dir
- 3.
- Create changelog, control, and (debs-only) Makefile from
"<file>.in" if they do not exist.
- 4.
- Run make in the build dir
- 5.
- Run lintian on the produced artifact (there must be exactly one)
- 6.
- Compare the result with the expected output.
A test in the "changes" suite
The changes test is fairly simple as there is not much building. The steps are
as the following:
- 1.
- Find or compute the test artifact as the following:
- -
- If <test-dir>/<test-name>.changes exists, it is used as
the artifact.
- -
- Otherwise, copy <test-dir>/<test-name>.changes.in into
the build dir and use it as a template to create
<build-dir>/<test-name>.changes. The result is then
used as the artifact to test.
- 2.
- Run lintian run on the artifact
- 3.
- Compare the result with the expected output
The full layout of a test in the "tests" suite¶
Each test in the "tests" suite is placed in
t/tests/<check>-<name>. In these you will find some of the
following files:
- -
- desc (mandatory)
This is the test description file. It is a deb822 file (i.e. same syntax as
debian/control), which contains a number of fields.
- -
- tags (mandatory, but may be empty)
This file contains the "expected" output of lintian.
This is generally sorted, though a few tests rely on the order of the
output. This can be controlled via the "Sort" field in the
"desc" file.
- -
- debian/ (optional, but usually what you need)
The unpacked debian package. For "native" package tests, this is
also the "upstream" part. For "non-native"
package tests, this can be used to override files in the
"upstream" part (rarely needed).
The actual packaging files (e.g. debian/rules) would be in
I<< t/tests/<test-name>/debian/debian/rules >>
Note the double "debian".
This part is seeded from t/templates/tests/<skeleton>/, where
skeleton is the value of the "Skeleton" field from the
"desc" file.
- -
- upstream/ (optional, rarely needed)
This directory is the used to create the "upstream" tarball for
"non-native" package tests. Since most tags are emitted for both
"native" and "non-native" tests, it is simpler (and
slightly faster) to use "native" packages for most tests.
The files here should also be present with the same contents in the debian
directory unless you're intentionally creating a diff. However, as normal
with a Debian package, you can omit files entirely from the debian
directory and the deletions will be ignored by dpkg-buildpackage.
The directory will be seeded from
t/templates/tests/<skeleton>.upstream/, where skeleton
is the value of the "Skeleton" field from the "desc"
file.
- -
- post_test (optional, rarely needed)
This script (if present) is a sed script that can be used to
"massage" the output of lintian before comparing it with the
"expected output".
The most common use for this script is to remove the architecture name,
multi-arch path, drop hardening tags or exact standards-version number
from tags output. Here are some examples files used:
# Remove the exact standards version, so the tags file will not need
# to be updated with every new standards-version
s/\(current is ([0-9]+\.)+[0-9]\)/(current is CURRENT)/
# Drop all hardening tags (they can differ between architectures)
/: hardening-.*/ d
# Massage e.g. usr/lib/i386-linux-gnu/pkgconfig into a generic path
s, usr/lib/[^/]+/pkgconfig/, usr/lib/ARCH/pkgconfig/,
It may be useful for other cases where the output of Lintian may change on
different systems.
- -
- pre_build / pre_upstream (optional, special case usage)
If present and executable, these scripts can be used to mess with the
package directory and (what will become) the upstream tarball.
Their common use case is to create files in the tarballs that cannot (or
preferably should not) be included in the revision control system. Common
cases include "binary", "minimized" files or files
with "weird" names such as backslashes or non UTF-8 characters.
Both scripts receive a directory as first argument, which is the directory
they should work on. For:
- -
- pre_upstream
The script will be run before the upstream tarball is compiled. The first
argument is the directory that will be included in the upstream
tarball.
- -
- pre_build
The script will be run before dpkg-buildpackage is invoked. The first
argument is the directory of the unpacked debian source package.
- -
- test_calibration (optional, special case usage)
If present and executable, this script will be invoked after lintian
and post_test (if present) have been run. The script can then
modify the expected output and the actual output.
This is useful for those extremely rare cases where post_test is
insufficient to handle the requirements. So far, this has only been needed
for the hardening checks, where the output differs between architectures.
The script will be passed 3 arguments:
- -
- Path to the "expected output" file (read-only)
This is the "tags" file from the test suite and must not be
modified.
- -
- Path to the "actual output" file (read-write)
This is the file as lintian and post_test created it.
- -
- Path to the "calibrated expected output" (create+write)
This file does not exist and should be created by the script, if it wishes
to change the "expected output". If this file exists when the
script terminates, this file will be used instead of the original
"expected output" file.
SEE ALSO¶
The READMEs in the suites:
t/tests/README,
t/changes/README,
t/debs/README and
t/source/README.
Lintian::Tutorial::WritingChecks, Lintian::Tutorial::TestSuite