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Tycho/Contributor Guide

Starting a Contribution

Before starting to develop an enhancement or fix for Tycho, it is important that you get in touch with the project. We track ideas for enhancements and bug reports in the Eclipse Bugzilla, so this is a good place to present your ideas for a patch and to make sure it's going in the right direction.

If you want to do a contribution but don't know where to start, you should to check the open bugs tagged with keyword "helpwanted". These are bugs with moderate complexity and estimated effort. In case of questions related to a contribution, you can also just ask on

Developing Patches for Tycho

The technical basics (how to get the sources, how to import and build, etc.) are described here: Developing Tycho .

Unless the patch is really trivial, make sure you include at least one test case that reproduces the bug or proves that the enhancement works.

Writing Tests

Tycho has two types of tests: unit tests (locally in each module) and a global integration test suite in module tycho-its.

Unit tests are preferred if possible because they are in general much faster and better targeted at the functionality under test. Integration tests generally invoke a forked Maven build on a sample project (stored under projects/) and then do some assertions on the build results.

See an example for a unit test and an integration test.

Commit Message Guidelines

  • Start with "Bug: <number>" stating the bug number the change is related to; this will enable the eclipse genie bot to automatically cross-link bug and gerrit proposal
  • Also in the first line, provide a clear and concise description of the change
  • Add one blank line, followed by more details about the change. This could include a motivation for the change and/or reasons why things were done in the particular way they are done in the change.
  • Add "Signed-off-by: <your_email_adress>" in the footer (see "Legal Paperwork" below).

See an example commit message

Commit Granularity

  • Make small commits, yet self-contained commits. This makes them easy to review.
  • Do not mix concerns in commits: have a commit do a single thing. This makes them reviewable 'in isolation'. This is particularly important if you need to do refactorings to the existing code: Refactorings tend to lead to large diffs which are difficult to review. Therefore make sure to have separate commits for refactorings and for functional changes.

Contributing the Patch

Legal Paperwork

Before your contribution can be accepted by the project, you need to create and electronically sign the Eclipse Foundation Contributor License Agreement (CLA) and sign off on the Eclipse Foundation Certificate of Origin.

Follow the instructions on Development_Resources/Handling Git Contributions

In general, also see Development Resources#Users: Contributing To A Project.

Pushing to Gerrit

The Eclipse Gerrit is the preferred way to propose patches to Tycho. Everyone with an Eclipse Bugzilla login can propose patches.

In order to propose a change to Tycho

  • Configure the repository URL for the remote "origin"
  • Know your Gerrit HTTPS user name and password
  • Push to the special code review branch "refs/for/master", e.g. with git push origin HEAD:refs/for/master

For more information on the Eclipse Gerrit instance (e.g. how to push via SSH), see here: Gerrit.

Note that prototypes and other incomplete work should be clearly marked as such e.g. by adding "POC" or "WIP" in the commit message, by commenting in Gerrit, or by pushing to the refs/for/master/POC topic branch. This avoids that committers spend time on reviewing incomplete changes.

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