Apache Commons is a collection of reusable Java components which are heavily used in most Java projects. The list of components to test is at: http://commons.apache.org/components.html
- The commons have a GitHub mirror at https://github.com/apache/commons-XXXX/
- All the projects use the Maven build system
- To build and test a project run the command
mvn test jacoco:report
- Coverage report is available in
./target/site/jacoco/index.html - To execute a single test (for example file MyTest.java) use the command
mvn -Dtest=MyTest test
- Suitable components for beginners are:
- commons-codec
- commons-collections
- commons-compress
- commons-configuration
- commons-csv
- commons-discovery
- commons-email
- commons-exec
- commons-imaging
- commons-lang
- commons-logging
- commons-math
- commons-net
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Work in teams of 4-5 people
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Select a project to work on - 1 project per team!
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Fork the project on GitHub
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Create a local branch for your changes
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Build it locally, execute the tests and generate coverage report with JaCoCo
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Investigate the coverage report to see where the component is missing coverage
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Determine what needs to be done in order to cover the missing lines. Don't write any code yet, just write down your results (e.g. I need method X to throw an exception and assert that this happened. For that I need input A and B).
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Identify what you need to assert in your tests. Helpful documentation can be found at http://junit.org! (e.g. how to assert an exception was thrown).
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Consult with instructor and your peers if the chosen test areas are appropriate
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After finding places which need coverage split in pairs
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Each pair of students select 1 method/class which isn't covered
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NOTE: copy the coverage results directory for backup (it will be used later)
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Investigate what the method does and write a unit test for it
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HELP: look for similar tests in the test suite, ask instructor for help
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After the test finally passes compare the new coverage with the old one. How much did you improve ?
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Reverse roles with your peer and write more unit tests. Coordinate with the rest of your team to avoid working on the same item.
- Prepare your tests for submitting a PR on GitHub
- Create a clean branch following master - 1 branch per change
- Cherry-pick individual commits
- Clean up comments, etc
- Re-run the test suite to make sure it passes
- Push the new branch to your GitHub repo
- Open a PR with the upstream project
- Ask instructor for help with the final wording if necessary
Follow up on your pull requests and aim to have them accepted upstream! Ask instructor and your peers for help if necessary.