JaCoCo - Development Conventions

# Development Conventions

Efficient team work that produces high-quality software requires a common set of rules.

## Consistent Source Tree

Follow the existing coding style and formatting rules. The projects contain auto-formatting rules for the Eclipse IDE.

Update your local branches and run the build locally before every push. Push only if the build succeeds and the configured compiler settings do not show any warnings in the Eclipse IDE.

Documentation is part of the product. Whenever you implement a new feature or change existing behavior make sure to update all corresponding JavaDoc as well as other documentation with the same change set. The product should always be in a consistent state. For every change the following items should be checked:

- Corresponding JavaDoc, every public type and member requires JavaDoc.
- Documentation referring to the modified concepts, interfaces or implementation.
- New features, bug fixes and modified behavior should be enlisted in the `org.jacoco.doc/docroot/doc/changes.html` file together with the corresponding issue tracker id.

## Design for Integration

The primary focus of the JaCoCo project is to provide a code coverage library. Integrators may want to embed JaCoCo in different tools and environments with very different usage scenarios. Therefore following aspects should be considered:

Documentation: All APIs should be properly documented on different levels of granularity:

- General usage
- Bundle summary
- Package summary
- Type description
- Member description

Proper Units: All APIs and internal implementation classes should form proper units with well defined responsibilities and dependencies. Each class and method should focus on a single concept. It should be possible to use different aspects separately.

Abstraction: All APIs must use the most general abstractions possible. For instance reading binary data should rely on the `java.io.InputStream` interface, not on a `java.io.File` object.

System Dependencies: Avoid any dependencies to the local file system, network resources, threads, processes etc.

## Test Driven Development

All code added to JaCoCo should have corresponding JUnit test cases. Ideally tests are developed before or along with the actual implementation:

- Every new feature should be verified by test cases.
- Modified behavior should also be reflected by test cases.
- Ideally for every reported bug a reproducer is added to the unit tests.

## Keep an Eye on License Issues

All code included with JaCoCo must conform to the EPL license.

- Every committer and contributor must agree that all code will be published under EPL. He or she must be the original author and must have the permission to contribute code to JaCoCo, for example if such a permission is required by the employer.
- Every third party content must be enlisted in the corresponding `about.html` file along with its license.
- Every third party content included with the JaCoCo distribution must be enlisted in the `org.jacoco.doc/docroot/doc/license.html` file and the corresponding `about.html` file along with its license.
- Every source file (Java, Build Script, DTD) must have a EPL license notice. The initial contributor should be listed. In case of significant changes or additions additional contributors should also be listed.

## Contribution process

All changes on the JaCoCo code base are handled via GitHub pull requests and always reviewed by a second developer. This applies for external contributors as well as for project members. Beside functional correctness every pull request needs to fulfill the conventions above.

For external contributors the following recommendations will help the project to incorporate their precious work:

- Get in touch: Before you start a bigger contribution please get in touch through our mailing list to make sure the JaCoCo project considers this in scope and the approach fits in the overall architecture.
- Clear scope: We track and review every semantical change through a separate pull request. Pull requests handling various topics ("I fixed this and that") are typically difficult in handling and are therefore declined.
- No technical debt: We are committed to maintain JaCoCo in the long run with on a high quality level. Therefore we will not accept contributions as long as they add technical debt to the project (e.g. lack of tests or design issues).