Feature/check code duplication

[eiditakahashi]

For now we have this setup:

• To use CPD, projects will need to set some variables on their Dangerfile:
  • @minimum_tokens, @language, @directory, @ssh, @target_branch
  • if any of these variables is not set CDP will not run showing a warning
• To run on CI we need to install pmd:
  • for projects using travis, we add - brew install pmd in .travis.yml
  • for projects using Jenkins, we add - brew install pmd in Jenkins script configuration

I am testing danger features here, the last warning is from CPD.

Depending on project CPD can turn in a bottleneck because it clones the repo to do comparison between feature branch and target branch. Here we can see that danger was executed in 41 seconds with CPD on this repo but I know that there are some huge repos (1GB+) 😕

So what you guys think about this approach @felipesabino @melloflavio

Pending:

• Install pmd on docker image
• Remove temporary directory (target-branch) to avoid garbage on local runs
• Check if pmd is not present on current build
• Update README list with this check

[felipesabino]

To use CPD, projects will need to set some variables on their Dangerfile:

My only fear is that we will start to have several loose variables on Dangerfile. Don't know the best apporach, may be using a Hash only for pmd values to be more explicit?

for projects using Jenkins, we add - brew install pmd in Jenkins script configuration

We can also install it on the docker image we use, then we don't have to wait for the installation on every build

---

Also:

• Can we warn if PMD is not present on current build? (travis.yml might be misconfigured for example and we should not crash if that's the case)
• Do you think we should experiment on copying and pasting current folder to another location and reseting it to @target_branch instead of cloning? No idea if it will be faster for big repos (specially as the CI also perform shallow clone)

[felipesabino]

Oh, forgot about remembering you to add a TODO/Pending here update README before finishing this PR

[felipesabino]

may be remove target-branch afterwards to avoid garbage on local runs