Cover all the things

2 minute read

This is one which has been on my list for a while. Coming from writing C# and being used to existing tooling and integrations with popular platforms to display information about your code, I kind of miss that when writing PowerShell. One of those is code coverage uploading and displaying on Coveralls.io. Not just because it’s cool, but it allows you to add that information to your repository and enforces you to either keep the current number or improve it. But, as it seems I once said something about not bitching and getting shit done, let’s fix that, shall we?

"You should get your work done instead of bitching about it" - another great quote from @Jan_Joris
I can only subscribe and say amem

— Jønatas C D (@JonatasCD) March 8, 2017

PowerShell has an awesome testing tool called Pester, if you’ve never used it, make sure to check it out. Pester had the ability to check for code coverage out of the box. It will list all lines within the specified files which have been hit, how many times they’ve been hit and what never got hit. Using this information, we can format that to send it to Coveralls for displaying. As I know everyone loves a bit of simplicity, I created a module called Coveralls that allows you to take advantage of this logic and use it wherever you’d like. In my case, I added it to the testing logic for modules on AppVeyor, so that the coverage is updated every time the code is tested on master. To do this you need to add a few lines to your appveyor.yml file.

First off, we need a key to push the results to Coveralls. Make sure to create a secure variable using the Coveralls API token for your repository.

environment:
    CA_KEY:
      secure: yyBVxcqc8JCSyOJf5I8ufwmwjkgMxouJ1ZyuCkAXdffDDU2VfZCZHK9lkHeph3SM

Secondly, we need to resolve a few dependencies.

before_test:
  - ps: Set-PSRepository -Name PSGallery -InstallationPolicy Trusted
  - ps: Install-Module Coveralls -MinimumVersion 1.0.5 -Scope CurrentUser
  - ps: Import-Module Coveralls

It could be you’ll also need the nuget provider, if you’d see an error indicating this, just prepend - ps: Get-PackageProvider -Name Nuget -Force to the before_test section.

Lastly, we need to format and publish the results.

test_script:
  - ps: $coverageResult = Format-Coverage -Include @('Helpers\PoshGit.ps1','Helpers\Prompt.ps1','install.ps1') -CoverallsApiToken $ENV:CA_KEY -BranchName $ENV:APPVEYOR_REPO_BRANCH
  - ps: Publish-Coverage -Coverage $coverageResult

There’s just one caveat here. As Keith Dahlby found out when we added this to posh-git, secure variables do not work on pull requests. This is done to avoid anyone decrypting and displaying that value and run away with your online identity, maybe ending up dating your wife and feeding your kids (the bastards!). As we don’t want that, make sure you either check you have a value in $ENV:CA_KEY and replace it with dummy info if not or don’t build on PR’s.

This example is coming from my oh-my-posh repository, where you can already see a neat Coveralls badge displaying the, somewhat disappointing, code coverage percentage. You can find more info about the module when you visit the project on GitHub. And yes, I do see the irony in having a module about code coverage with 0 tests and no lovely badge. It’s on my list, ok? Don’t be a dick about it.

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