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How to contribute to Lintian

This document is intended for prospective and existing contributors.

The first section will cover how to get started for newcomers. After that is a section on recommended practices and additional resources.

Understand the codebase

Core Directories

  • bin/: Contains the main Lintian executable scripts.
  • lib/: The core Lintian library code.
    • Lintian/: Most of Lintian's Perl modules are here.
      • Check/: Individual check modules that implement Lintian's various checks.
      • Collect/: Collector modules that gather data from packages.
      • Tag/: Modules related to Lintian tags.
  • data/: Contains data files used by Lintian, such as lists of valid maintainers, architectures, etc.
  • t/: Contains the test suite.
    • recipes/: Test cases for Lintian checks.
  • doc/: Documentation files, including the Lintian User Manual source.
  • reporting/: Code for generating HTML reports from Lintian output.
  • private/: Various helper scripts used for development and testing.

Key Files

  • frontend/lintian: The main Lintian script that users run.
  • lib/Lintian/Profile.pm: Defines the Lintian profile, which controls which checks are run.
  • lib/Lintian/Processable.pm: Represents a processable object (e.g., a .deb or .changes file).
  • lib/Lintian/Collect.pm: Base class for collector objects.

Overview of adding a new check

To add a new check to Lintian:

  1. Create a new module in lib/Lintian/Check/.
  2. Implement the check logic.
  3. Add test cases in t/recipes/. Testing explained in detail below.

For classification tags, which indicate a characteristic of a package rather than a policy violation, the process is similar:

  1. The check module (e.g., lib/Lintian/Check/VersionControl/GitBuildpackage.pm) emits a tag (e.g., uses-gbp-conf).
  2. The tag's definition is in tags/<first-letter-of-tag>/<tag-name>.tag (e.g., tags/u/uses-gbp-conf.tag), and its Check: field must point to the check module's path (e.g., version-control/git-buildpackage).
  3. The test recipe directory t/recipes/checks/<check-path>/<test-name>/ (e.g., t/recipes/checks/version-control/git-buildpackage/git-buildpackage-conf/) should mirror the check module's logical path.
  4. The Testname: field in eval/desc and build-spec/fill-values should match the <test-name> part, and the Check: field in eval/desc should match the check's path.
  5. See commit 6a62aa56 as an example of adding a new classification tag.

Contributing on Salsa using git

The best way to contribute code to Lintian is to submit merge requests on salsa.debian.org. First, create an account on Salsa if you do not have one. You need to configure at least one SSH key.

The easiest way to file merge requests on Salsa is to fork our team repository into your private namespace. That is done on the Salsa website.

Then you should clone the forked version of Lintian from your private namespace to your local machine. You can find the command for that under a blue button that says "Clone". Choose the git protocol (not HTTPS).

git clone git@salsa.debian.org:${your-namespace}/lintian.git
cd lintian

Create a feature branch for your proposed changes.

git checkout -b my-feature

View git history to follow existing conventions

Now you can fix bugs or implement new features.

Please commit your changes with suitable explanations in the commit messages. You can find some examples with:

git log

Please do not touch debian/changelog. We automatically update that file at release time from commit messages via gbp dch.

The first line of your commit message is special. It should make sense without any context in a list of other, unrelated changes.

Tell us how to test your work

All new tags require unit tests. Lintian's test suite will fail unless you provide tests for your proposed tags.

There is a way to exempt your tag from testing.

Most tests only run a specific lintian 'check'. Please name your tests after this check: do not name them after the tag they are testing because many tags need two or more tests to exercise subtle variations in the trigger conditions.

Test specifications have two parts, build specifications and evaluation specifications. Build specifications tell the testsuite how to build a test package, and evaluation specifications declare how to run Lintian on the package and say what the expected output is.

Build specifications are located in the directory t/recipes/path/to/test/build-spec/. This must contain:

  • A partial debian/ directory that includes as little packaging files as possible
  • An optional 'orig' directory containing upstream files (if any are needed to trigger the tag)
  • A file called 'fill-values' that tells the test suite how to use existing template to 'fill in' anything not included in debian/

For most tests, debian/ will be very minimal indeed. A simple 'fill-values' might look like this:

Skeleton: upload-native
Testname: pdf-in-etc
Description: Ships a PDF file in /etc

This will use the 'upload-native' template to create a native package with the given 'Description'. The 'debian' directory would have a one-line 'install' file putting some PDF documentation in /etc, and a PDF file would be included in orig. (Please do not look for this test in the test suite; it is just an example).

Evaluation specifications are located in the directory 't/recipes/path/to/test/eval/'. These describe how to run Lintian and which output (tags, exit code) to expect.

The main file is 'desc'. A simple evaluation specification might look like this:

Testname: pdf-in-etc
Check: documentation

As noted, this will only run the specified 'documentation' check. This keeps output to a minimum so you do not get nuisance tags, such as debian-watch-does-not-check-gpg-signature (unless you are working on the a check for debian/watch). The contents of the 'Testname' field must match the directory name.

A 'hints' file in the eval directory contains the tags that lintian is expected to be produce when run on the test package. Only tags from the selected 'check' should be included.

You should scrupulously examine the 'hints' to make sure your tags show up exactly the way you want, but you do not have to write it yourself. The test suite will help you write this during the interactive calibration described in the next step.

Further details are in the file t/recipes/README.

Preparing to run the test suite

To run the testsuite you probably have to install all testsuite prerequisites from Lintian's debian/tests/control. This can be done with:

autopkgtest -B

You may also have to install the build dependencies with:

apt build-dep .

Both of these commands have to be run with root privileges.

Running the testsuite

To run all tests run

private/runtests

This takes a long time the first time you run it because Lintian has a large number of tests each building its own test package. The packages are built locally (in debian/test-out/) and reused so subsequent runs are much faster.

To run a subset of tests, use --onlyrun:

private/runtests --onlyrun=check:documentation

This runs all tests that have 'Check: documentation' in their 'eval/desc' file. Alternatively private/runtests --onlyrun=test:name will run a single test with 'Testname: name'. Running private/runtests --help will show you further options.

Calibrating tests to fix test failures

If tests fail, the testsuite will use an interactive 'calibration' process to help you write or amend a 'hints' file. Simply follow the instructions on the screen. In many cases, it is best to "accept all" and examine the changes in git. In complex cases, you can use git add -i to stage only the changes you need.

This is a crucial step when adding a new test. Please make sure the expected tags are correct. We pay close attention to these tags when we look at your merge request.

Run the full test suite

Once your test is correct and passing, please ensure the entire test suite passes. This includes a variety of style and consistency tests.

The most common issue detected is that you have to run perltidy. We configure perltidy in a special way. Please run it from the repository's base directory. Otherwise it will not find the custom configuration, and the test suite will not pass.

Run perltidy

The program perltidy is provided by the package perltidy.

The program prove is provided by the package perl.

On all files

prove -l t/scripts/01-critic/

On recently changed files

On the 10 last commits

git diff --name-only HEAD~10 HEAD | grep -F ".pm" | xargs perltidy -b

Submit a merge request

Once all the above is done, please push your changes to your Lintian fork on Salsa.

You may end up doing that multiple times: use git push -fv to keep the git history simple.

After each push you will be shown a link to create a merge request. Just click the link provided in the terminal. Your browser will open a draft merge request. For a single commit, the text field is populated with your commit message. Otherwise, please explain the purpose of your commit series and hit "Submit".

The push command also started the standard CI pipeline on Salsa, which is very comprehensive. It builds Debian packages and runs autopkgtest, among many other jobs.

We will generally not accept merge requests unless the CI pipeline passes successfully. You can see the status on Salsa in two places: in the MR and in your own repo. The pipeline takes about one hundred minutes.

There is no need, however, to wait for Salsa CI pipeline before submitting your merge request. If you followed all the steps above, it will very likely pass.

Other ways to submit changes

Please make an effort to submit your changes to Lintian by creating a merge request on Salsa. When submitting on Salsa, ensure you have Salsa CI enabled and if the Lintian test suite reports any failures, please review them.

Alternatively, submit your changes to the Debian Bug Tracker by reporting a bug against the lintian package. On a Debian system, this can usually be done by using reportbug:

reportbug lintian

Otherwise send a plain text mail to submit@bugs.debian.org with the first line being Package: lintian:

You are welcome to attach the changes to the bug report or link to a git branch. If you use attachments, please generate the changes via the git format-patch command.

Recommended practices

The "master" branch is "always releasable"

We try to keep the "master" branch in a clean state that is suitable for release at all times.

For topic branches that are not yet suitable for release, please point us to your personal repository on Salsa or file a merge request with WIP: in the title.

Backport requirements

There are some limits to which changes Lintian can accept as it needs to be backportable to the current Debian stable release. As such, all dependencies must be satisfied in Debian stable or stable-backports.

There are several reasons for this requirement. The two main ones are:

  • Lintian is run on various debian.org hosts which are all running Debian stable (ftp-master.debian.org)

  • Many developers use stable and will want easy access to an up to date Lintian.

Accordingly, we have continuous integration job running on jenkins.debian.net to test this.

Additional resources

Making a release

First ensure that test suite pass both locally and on Salsa.

Then make a release commit by running the following command (make sure the DEBEMAIL and DEBFULLNAME variables are set)

gbp dch -R --postedit="private/generate-tag-summary --in-place"

Check if commit message and changelog are in good shape (edit if needed and amend commit). Then build as usual.

When lintian hit unstable or experimental, add tag using gbp tag and open a new version by:

private/generate-tag-summary --in-place