Add JUnit reporter

[mrdannael]

Closes #568

PR aims to implement a reporter for generating JUnit xml. Without --reporter-options it will output the results to the console. By providing path value, the reporter will try to put the output into the file.

Added small "fast-xml-parser" package to the knip package.

Also updated the docs with info about Junit reporter.

[webpro]

I don't know anything about this format, but will each issue be in its own node, or should it be? This example gives me the impression that all unlisted dependencies will end up in this single node? Or will each one have the "Unlisted dependencies: " prefix?

Maybe you could show an example of how it looks like in the CI environment (eg. Bitbucket)?

[mrdannael]

Sure thing. I've already used this junit reporter during development and tested it with configured Bitbucket. I'll gather some real-life data and post it here for further discussion.

[webpro]

Is there still interest in wrapping up this pull request?

[mrdannael]

Yeah, absolutely.
Thanks for the reminder.

That's how bitbucket diplays the test results file.

But now i see that there are some differences between bitbucket output and the test case provided within PR.
They don't match. I'll try to re-generate the output again.

[mrdannael]

This is the actual output from junit reporter on Bitbucket pipelines run on the live project:

And this is part of the output xml file that was reported after running knip (in txt because Github won't allow to attach xml file). I've cut some sensitive data from the file (that's why issues count don't match with the image from BB).

test-knip-report.txt

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[webpro]

I feel like we could improve the output a bit.

For instance, I see this in one section:

json.Unused devDependencies package ⋁

1 Unused devDependencies - postcss-scss
2
3 Unused devDependencies: "postcss-scss" inside package.json
4

Maybe all unused devDependencies of a file can go into a single foldout, without the duplication? Eg:

Unused devDependencies in package.json ⋁

1 postcss-scss
2 postcss-syntax

Doesn't need to be perfect, but I wonder how close we can get to something more like this?

[mrdannael]

I need to test if BitBucket will accept something like that

<testsuite name="Unused dependencies" tests="1" failures="4">
    <testcase tests="1" failures="4" name="Unused dependencies" classname="package.json">
      <failure message="Unused dependencies - @types/google.accounts" type="Unused dependencies">Unused dependencies: "@types/google.accounts" inside package.json</failure>
      <failure message="Unused dependencies - fast-xml-parser" type="Unused dependencies">Unused dependencies: "fast-xml-parser" inside package.json</failure>
      <failure message="Unused dependencies - type-fest" type="Unused dependencies">Unused dependencies: "type-fest" inside package.json</failure>
      <failure message="Unused dependencies - web-vitals" type="Unused dependencies">Unused dependencies: "web-vitals" inside package.json</failure>
    </testcase>
  </testsuite>

or other similar output. If yes, then more compact output without duplications should be possible.
I'll try different formats.