Offer test result output for CI

[rjmholt]

Integrating PSSA into CI pipelines may mean getting it to report output nicely. For example, Azure DevOps can understand, display and use the output of e.g. NUnit XML. (link)

I suspect most users currently use Pester to do this, but we could do it directly.

[bergmeister]

Current workaround is to use the following code created by the community or use Pester, which can create NUnit XML as well.
https://github.com/MathieuBuisson/PowerShell-DevOps/blob/master/Export-NUnitXml/Export-NUnitXml.psm1
This is something we'd look at post PSSA 2.0

[clcaldwell]

I think PSScriptAnalyzer needs this. From my perspective, we should support several common formats - something like NUnitXML, JUnitXML, and Checkstyle (common output for Linters in other languages).

For large projects, there is a a very large performance penalty for running all Script Analyzer checks through Pester (as well as it just being un-intuitive and cumbersome). And while @MathieuBuisson 's Export-NUnitXML works - it introduces another dependency (one which is not available through the PSGallery), and only supports 1 output format.

I am willing to take a shot at implementing this. My initial though it to have this like Pester does, with output params, but we could also add a dedicated cmdlet for export:

Invoke-PSScriptAnalyzer -Outputformat (CheckStyle, Junitxml, Nunitxml) -OutputFile blah.xml
Invoke-PSScriptAnalyzer | Export-ScriptAnalyzerResults -Outputformat (CheckStyle, Junitxml, Nunitxml) -OutputFile blah.xml

[Tzrlk]

Btw, if anyone wants code to do the checkstyle output: https://gist.github.com/Tzrlk/fc8e0a1c7a3eb30bda600d355004bc0f

I'll update it once I'm done extracting the keys bits into a function.