Tycho/Contributor Guide

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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 an enhancement but don't know where to start, you can also just ask on tycho-dev@eclipse.org.

Developing Patches for Tycho

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

If the patch is not trivial, make sure you include a 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 output.

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

Commit Message Guidelines

  • Start with the bug number the change is related to; don't add "bug" or puctuation marks
  • 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 "Bug: <bug number>" in the footer.

See here for 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

Using 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 https://git.eclipse.org/r/tycho/org.eclipse.tycho.git 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 pushed to the refs/for/master/POC branch so committers know the nature of the changed being pushed.

Using Bugzilla

Attach the patch(es) to the bug/enhancement in Bugzilla. The patch should be in the format produced by git format-patch, so that it is suitable for git am.

Legal Paperwork

With the contribution, you will have to include answers to the following questions (e.g. as comment in Gerrit or Bugzilla):

  1. Did you author 100% of the content you are contributing?
  2. Who owns the copyright of the contributed content? (This is typically your employer.)
  3. Is the contributed code licensed under the EPL? (You should answer this question by putting a copyright and license header into every new java file.)
  4. Do you have the right to contribute the content to Eclipse? (You need to confirm this with the copyright owner.)

With these questions answered, we will be able to accept small patches (<250 LoC) immediately. For larger patches, we will also have to create a contribution questionnaire for review by the Eclipse IP team, but this usually doesn't require additional actions from you.

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