CPD (Copy Paste Detecor)
Detecting duplicated code is a good way to make source code clean. Since I couldn't find how to detect duplicated code in Golang, I sent a pull request that CPD(Copy Paste Detector) is able to accept Golang. CPD is a software included in PMD.
And there is a useful Jenkins plugin, DRY. It visualizes how much duplicated code exist. I'll show you how to make it visible with Jenkins.
Setting up Jenkins
Use docker-toolbox to shortcut installing jenkins. After installing docker-toolbox, you just type following command.
$ docker run -p 8080:8080 jenkins
Installing PMD Plugin
- Click "Manage Jenkins" on a top page
- Click "Manage Plugins"
- Click "Available" Tab
- Select "Duplicate Code Scanner Plug-in"
- Click "Download now and install after restart"
- Jenkins will be restarted after plugin installed
Create a job to detect duplicated code
We'll use terraform repository as an example.
- Click "create new jobs" on a top page
- Select "Freestyle project" and type name for your job.
- Click Add build step and select "Execute shell" and paste following shell commands
export PMD=pmd-bin-5.3.3 if [ ! -d $PMD ]; then curl -o $PMD.zip -L -O http://downloads.sourceforge.net/project/pmd/pmd/5.3.3/pmd-bin-5.3.3.zip\?r\=http%3A%2F%2Fsourceforge.net%2Fprojects%2Fpmd%2Ffiles%2Fpmd%2F5.3.3%2F\&ts\=1440850447\&use_mirror\=jaist [ -e $PMD.zip ] && unzip $PMD.zip fi [ ! -d terraform ] && git clone https://github.com/hashicorp/terraform.git $PMD/bin/run.sh cpd --minimum-tokens 100 --files terraform --language go --format xml > cpd.xml || echo
- Click "Add post-build action" on "Post-build Actions" and select "Publish duplicate code analysis results"
- Duplicate code results: cpd.xml
- High priority threshold: 50 (default)
- Normal priority threshold: 25 (default)
- Save the job and run it.
- We can see a link "Duplicate Code" on the job page
Options of CPD
- --minimum-tokens: The minimum token length which should be reported as a duplicate. I recommend 70 - 100.
- --files: a directory to check duplication.
- --language: a programming language.
- --format: xml or plain
For further information, type following.
pmd-bin-5.3.3/bin/run.sh cpd -h
We can detect duplicated code with CPD and Jenkins.