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EGit/Contributor Guide

< EGit
Revision as of 09:06, 26 March 2011 by (Talk | contribs) (EGit Core Tests: Mockito)

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This page is currently under construction. Community members are encouraged to maintain the page, and make sure the information is accurate.
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Development IDE Configuration

EGit and JGit have Java 5.0 and Eclipse Platform 3.5 as minimum requirements, so dependencies to newer Java and platform versions must be avoided.

In order to minimize the inadvertent introduction of dependencies to Java 6.0, add both a Java5 and a Java 6 SDK to your workspace. Do this in Window/Preferences -> Java/Installed JREs. Then configure your Execution Environments so that J2SE-1.5 refer to a Java 5 SDK and JavaSE-1.6 refer to a Java 6 installation.

To be completely on the safe side for reducing the risk of breaking Platform 3.5 compatibility, you would have to have a 3.5 IDE ready on which to check your code. In general, the effort for this is probably not justified, unless you are introducing major UI functionality. Just keep the minimum requirements in mind when using Platform API. Eclipse API's are usually marked with a @since tag.

If you are using OS X Snow Leopard, then Java 5 is hard to find. Using the search button in Eclipse will tell you that you have a 1.5.0 version of Java. That is probably a lie. It is just a link to 1.6. Fortunately some nice guys have made a download that you may use. Follow these instructions to download and installl a real Java 5. You do not need to make it default. Downloading, unpacking and fixing the version links is enough.

Obtaining Sources

EGit and JGit are self hosted in Git. Browse the repositories in gitweb.

There are several ways to obtain a copy of each repository:

From the command line

git clone jgit
git clone egit
git clone egit-pde

From an installed EGit plugin

  • File > Import > Git > Git Repository
  • Clone
  • Enter URI:
  • Import projects
  • File > Import > Git > Git Repository
  • Clone
  • Enter URI:
  • Import projects

To compile you also need libraries from Orbit.

EGit PDE Tools

EGit also provides tools for integrating with PDE Build and Eclipse RelEng Tools. If you are an Eclipse developer using PDE Build and/or the Eclipse RelEng tools you might be interesting in the following as well. Otherwise you might just skip this section.

  • File > Import > Git > Git Repository
  • Enter URI:
  • Import projects

EGit GitHub Integration

EGit also provides tools for integrating with GitHub and Mylyn tasks.

  • File > Import > Git > Git Repository
  • Enter URI:
  • Import projects

In addition to the libraries from Orbit required for JGit and EGit you also need Eclipse PDE (>= 3.6.1) as well as in your target platform or checked out from CVS in your workspaces.


EGit and JGit builds run on via Hudson using



  • JGit can be built using Maven 2 or 3.
  • JGit packaging project (Eclipse feature and update site) are built using Maven 3 and Tycho.


  • EGit is built using Maven 3 and Tycho.

Mailing Lists

If you're interested in following builds, please check out the following mailing lists:

Maven Build Sequence

Complete build sequence for a clean build (assuming $M2_HOME/bin is on the path and local Maven repository at ~/.m2/repository):

[~/src/jgit] $ mvn clean install
[INFO] Scanning for projects...

[~/src/jgit] $ mvn -f org.eclipse.jgit.packaging/pom.xml clean install
[INFO] Scanning for projects...

[~/src/jgit] $ cd ../egit

[~/src/egit] $ mvn clean install
[INFO] Scanning for projects...

The EGit build uses the JGit p2 repository to resolve jgit dependencies. For local builds the build assumes that egit and jgit source trees are located under a common parent folder. If this is not the case the path to the jgit p2 repository has to be injected via system property:

[~/src/egit] $ mvn clean install -Djgit-site=file:/path/to/

The hudson build on uses:

[~/src/egit] $ mvn clean install -Djgit-site=


The EGit and JGit builds are published via a shell script on (you need SSH access to the machine to publish. At the moment, Chris Aniszczyk (caniszczyk) and Matthias Sohn (msohn) have publishing privileges). There are two scripts that drive the publishing process:


The script essentially fetches the latest successful build from Hudson and publishes it every three hours via a cron job.


To sign the EGit build, you need to have ssh access to and the ability to run /usr/bin/sign

At the moment, Chris Aniszczyk (caniszczyk) and Matthias Sohn (msohn) have signing privileges.

The first step is to ensure you're in a place you can sign on

cd /home/data/httpd/download-staging.priv/commonBuild

Next you run the signing command (Usage: /usr/bin/sign <file> <mail|nomail> [outputDir]) on a zip of the EGit repo...

sign /home/data/users/caniszczyk/egit-0.8

After that, you can publish the zip that is generated with the signing information.

FindBugs and PMD

As part of the build, JGit and EGit run FindBugs and PMD to find issues.



Trends EGit JGit
Open Bugs and Enhancements Open Open
Assigned Bugs and Enhancements Assigned Assigned
All Bugs and Enhancements All All
Lists EGit JGit
Open Bugs Open Open
Open Enhancements Open Open
Assigned Bugs and Enhancements Assigned Assigned
Reports EGit and JGit
Open EGit and JGit Bugs Open
Assigned EGit and JGit Bugs Assigned


To simplify bug management we started to tag EGit bugs with additional pseudo keywords (not normal Bugzilla keywords). The tags are prepended to the bug's summary field. Since we use these tags for internal bug management reporters of a bug should not add any pseudo keywords when filing the bug. The owner of the component bucket is responsible to add the keywords.

Keywords are used to group bugs without assigning them to a developer. So with the introduction of the keywords it is easy to search for all bugs belonging to a specific sub component. For example to get an overview of all open refactoring issues search for new, assigned or reopened bugs containing the word [refactoring] in the summary field.

Be aware that not all bugs are tagged with keywords, only bugs that belong to a certain sub group may have a tag attached. The following lists some of the currently used tags.

Tag Description Link
[sync] everything related to Synchronize / Synchronize View View bugs
[repoView] everything related to the Git Repository View View bugs
[releng] everything related to release engineering and build View bugs
[historyView] everything related to the Git History View View bugs


The EGit project sources its documentation from the wiki and generates Eclipse help content from it (under the covers, we are using Mylyn WikiText to make this possible). This significantly lowers the barrier for people to contribute documentation to the EGit project. To contribute documentation, simply modify the EGit User's Guide. Have a look at the Style Guidelines and Eclipse Documentation Style Guide to get some guidance on how to write good documentation. More on that can be found here.

The documentation is contained in the org.eclipse.egit.doc plug-in. The build-helper.xml drives the generation of the help content. It is integrated into the maven build. The regular maven build of org.eclipse.egit.doc

$ mvn clean install 

will only package the help content committed to the egit repository. To update the help content by downloading the latest documentation from the wiki run

$ mvn clean install -Dupdate.egit.doc

Don't forget to check all the generated help pages and especially all hyperlinks and images before pushing the updated help to the code review system for inclusion into the continuous build.

The aim is to generate new documentation every month or so (or just on demand). If you're making big changes or want the documentation refreshed, please let us know on the egit-dev mailing list.


JGit Unit Tests

The JGit unit tests are executed during the maven build for the bundle org.eclipse.jgit.test. To run them from the Eclipse workbench use the launch configurations which are part of the sources of the bundle org.eclipse.jgit.test.

JGit HTTP Tests

The JGit HTTP tests rely on the Jetty web container. To run these tests from Eclipse install the jetty feature.

If you are using Helios you can get it from here:

Otherwise install it from here:

Feature: Jetty - Core: servlets and webapps

EGit Core Tests

The EGit Core tests are executed during the maven build for the bundle org.eclipse.egit.core.test.

To run them from the Eclipse workbench use the launch configuration which is part of the sources of the test bundle org.eclipse.egit.core.test. You will also need to install Mockito, see Libraries from Orbit.

EGit UI Tests

The EGit UI tests are using SWTBot, to run them you need 'SWTBot for Eclipse Testing' feature.


Install the SWTBot matching your Eclipse version

You need to install at least "SWTBot for Eclipse Testing" and "SWTBot IDE Feature".


Using target platform definition file:

  • provides core Galileo-based dependencies and SWTBot for Eclipse Testing feature. You still need JGit projects to be opened in the workspace.
  • extends the previous one with JGit from the nightly update site. This patch makes it possible to develop EGit plug-ins without checking out JGit projects.

How to use it:

  • pull either first or both patches
  • open Target Platform Preferences page (Window - Preferences - Plug-in development - Target Platform)
  • activate 'SWTBot-based UI plug-in tests' target platform

During Maven Build

The tests are executed in the integration-test phase of the default Maven lifecycle.

Auxilary testing tools

Any code, including testing code, does not always do what you expected it to. The most common failure is probably the failure to actually execute the part of the code you wanted to test. Code coverage tools like EclEmma can easily visualize what part of the code is being executed.


The EGit and JGit websites are located in a CVS repository on the Eclipse Foundation's servers.


  • File > Import > CVS > Projects from CVS
  • Select URL
  • Use module egit (from www)
  • Finish


  • File > Import > CVS > Projects from CVS
  • Select URL
  • Use module jgit (from www)
  • Finish

Contributing Patches

Review the following style guides:

Currently the project is alpha-testing Gerrit Code Review for Git based patch submission and review. To use the alpha testing instance hosted at

  • Register a user account
  • Use Register New Email to register your email address with our Gerrit Code Review server. This step is required to validate the address is correct.
  • Add one or more public SSH keys
  • Execute SSH once to accept the host key (or copy it from the registration web page)
ssh -p 29418
  • Confirm you agree to the Terms of Service by completing the Individual Contributor agreement.
  • Upload your patch from Git to the target project:
    • JGit
git push ssh:// HEAD:refs/for/master
    • EGit
git push ssh:// HEAD:refs/for/master

Or, create a new bug and attach a Git formatted patch file, as produced by the `git format-patch` tool.

Granularity of Changes

  • Make small commits, as small as reasonable. This makes them easy to review.
  • Each commit should have a commit message that explains very clearly what the commit sets out to achieve (unless this is abundantly clear from the code itself, which is basically only the case for trivial patches). Also, when you fix a bug then report which bug you fix. When there are deeper reasons for doing things the way the commit does, then explain these as well. This all is for the reviewers and yourself: the context of the commit is completely clear.
  • Do not mix concerns in commits: have a commit do a single thing. This makes them reviewable 'in isolation'. The purpose of the commit is clear and can be understood easily by the reviewers and yourself.
  • Do not break the build and tests for any commit: this is very important for bug hunting.
  • Split your work into multiple smaller pieces of work (when possible) and implement each of these pieces in a series of commits.
  • A series of commits should work towards a 'feature' in a clear way and only 'enable' the feature in the last commit of the series.
  • In a series of commits first lay the groundwork and then build on that towards the feature.
  • Do not mix concerns in branches: when you encounter a bug while working on something then create a new branch to fix the bug. If your work depends on the bug being fixed then rebase your work on that new branch.

Commit message guidelines

  • The commit message header should fit on one line and should start with an uppercase letter
  • The commit message have newline characters after every 60-70 characters.
  • If a Gerrit Change-Id is available (for example when re-submitting to the same change), it should be added in the format below
  • If there is an associated bug number in Bugzilla about it, it should come right before Gerrit's Change-Id entry (if available) or towards the end.
  • A "Signed-off-by" should be added to the end of the commit message (see example below).
  • The first sentence should be a clear and concise description about the change.
  • Enter a newline before providing a more detailed description about the change.
Fix the commit dialog to respect the workbench's selection

Originally, the commit dialog would automatically check off all
files in the dialog. This behaviour contradicts a user's expectation
because their selection in the workbench is completely ignored. The
code has been corrected to only preselect what the user has actually

Bug: 12345
Change-Id: I71ac4844ab9d2f848352eba9252090c586b4146a
Signed-off-by: Your Name <>

Test before submitting

  • Run all existing tests. It does not take very long.
  • Pay attention to the Java and Eclipse SDK baselines. EGit requires only Java5 and Eclipse 3.5. You cannot use API's that are newer. We often see breakages because Java 6 API's are used.

Adding a remote

Since git can have multiple remotes, you can define one to be used to refer to Gerrit to save typing. Inside a previously checked-out repository you can run:

cd path/to/jgit
git config ssh://
git config HEAD:refs/for/master

cd path/to/egit 
git config ssh://
git config HEAD:refs/for/master

You can now submit review requests from either repository using:

git push review

Sending patches by mail

Although sending patches by mail is the approved way of interacting with, and asking feedback from, the Git project, please don't send patches via git send-email. Instead, please use git format-patch to generate the mbox, and then attach that to an item in bugzilla as per the above SUBMITTING_PATCHES guides.

If you're sending a work-in-progress for a review, be aware that you can also attach work-in-progress (or RFC) items to Bugzilla; it's not just for finished patches.

However, it's generally preferred that you send items which you want comments on via Gerrit as per #Adding_a_remote, since Gerrit allows comments to be added in-line and allows the opportunity to send multiple versions of a patch after changes are made. Once a change has been submitted to Gerrit, you can then mail the developer mailing list with a request to review your change via URL or get Gerrit to send the mail on your behalf.

Gerrit Code Review Cheatsheet

Install the commit-msg hook in your repository

scp -p -P 29418 .git/hooks/

This will ask for a password. It is the password that you have to generate in the SSH Keys section of settings in your Gerrit account.

You can alternatively download the file. The hook helps append a Change-Id to your commit message.

To create a new change

  • JGit
git push ssh:// HEAD:refs/for/master
  • EGit
git push ssh:// HEAD:refs/for/master

Or, if you've followed the instructions on #Adding_a_remote you can simply do:

git push review

Since the current repository has the right definition for 'review', you won't need to remember the canonical push URL

To update an existing change with a new commit

git push ssh:// HEAD:refs/for/master

This works because Gerrit links the new commit to the prior change based upon the Change-Id footer in the commit message. (This is automatically generated by the commit-msg hook you installed above.) If you refuse to use the commit-msg hook, or don't have a Change-Id footer, you should read the Gerrit documentation on change-id lines and replacing changes.

Note: To be picked up by Gerrit, a Change-Id line must be in the bottom portion (last paragraph) of a commit message, and may be mixed together with the Signed-off-by, Acked-by, or other such footers. So if your Change-Id line is ignored it's probably not in the last paragraph :).

To compare bulk diffs using Git

Since each Gerrit review patchset actually commits its own tree, you can pull out the trees and compare them.

If you've got a large changeset, and you want to be able to do diffs between them via (command line) git instead of browsing on the web, then you can fetch the individual changes and then perform a diff. For example, shows the 'download' section for each patchset. In this case, it looks like:

Performing a git pull will both get the bits and merge them into your tree, which won't do what you want for comparison. So, in order to get the bits (but not merge), you need to do a git fetch instead. Let's say we want to diff the last two patches against each other rather than reviewing the entire patchset again:

git fetch git:// refs/changes/02/2/3
git fetch git:// refs/changes/02/2/4

git diff d14cc645655683ba3e30a35833fb2282142e898f 43de8d385b614c72fd796e17da75d381f6e0cc25

# or git diff d14cc6 43de8d

If you're doing this from within an already checked out project, you can do git fetch origin (or any other remote name in .git/config}.

Git fetched data will stay around in your repository, but will be 'orphaned' if no references point to it. To clean up, you can run git gc or wait until this happens automatically.

To approve a change

  • Click on Publish Comments
  • Vote with the radio buttons

To add a reviewer

Once you've pushed your commit to Gerrit for review, you can go to the web page ( and see your changes. By clicking on the review, there's an option to add a reviewer by e-mail address; they'll then be sent a message indicating that they'd like your review on the item.

Code Review

The code review category indicates your opinion on the quality of the code, and how well it fits within the purpose of the existing surrounding code. A +2 vote from any committer is required before submission can occur. A -2 vote from any committer will block submission.

IP Review

The IP review category indicates whether or not the change has been properly logged under the eclipse IP process. Under that process, any committer should mark his/her change +1 if they were the sole author of the change. For any other change, a committer should only mark +1 after ensuring the corresponding bug in Bugzilla has been updated with the iplog flag, or the corresponding CQ has been marked checkintocvs. For contributions from external contributors have a look at the detailed rules. A +1 vote is required to submit a change, while a -1 vote will block submission.

Submission Guidelines

We strive to use Gerrit to improve our understanding of the code base and improve quality.

In order to ensure a proper review happens, some simple guidelines should be followed:

  • vote 0/-1 for not-ready-to-submit (AKA WIP) own proposals, +1 otherwise;
  • If a changeset is not-ready-to-submit, please put [RFC] or [DRAFT] in the message to let people know
  • let non-trivial changes be in review for at least 24 hours
  • if you want your changeset reviewed by someone, please add them as a reviewer

Libraries from Orbit

Import Team Project Set

The simplest way to import the 3rd party libraries needed to compile JGit and Egit:

  • Download the Team Project Set for git dependencies
  • File > Import > Team > Team Project Set
  • Next
  • Select the downloaded GitDependencies.psf
  • logon with user "anonymous", leave password field blank
  • Finish

Manual Import


  • File > Import > CVS > Projects from CVS
  • Select URL
  • Use module org.eclipse.orbit/org.mockito
  • Finish
  • Right click on the project > Team > Switch to another branch
  • Select tag from following list
  • Refresh Tags
  • Versions > v201102171835


  • File > Import > CVS > Projects from CVS
  • Select URL
  • Use module org.eclipse.orbit/org.objenesis
  • Finish
  • Right click on the project > Team > Switch to another branch
  • Select tag from following list
  • Refresh Tags
  • Versions > v201006030720


  • File > Import > CVS > Projects from CVS
  • Select URL
  • Use module org.eclipse.orbit/org.kohsuke.args4j
  • Finish
  • Right click on the project > Team > Switch to another branch
  • Select tag from following list
  • Refresh Tags
  • Branches > v2_0_12


  • File > Import > CVS > Projects from CVS
  • Select URL
  • Use module org.eclipse.orbit/javax.servlet
  • Finish
  • Right click on the project > Team > Switch to another branch
  • Select tag from following list
  • Refresh Tags
  • Branches > v2_5

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