How do fail a Packer pipeline upon powershell provisioner pester test failure?

I'm building a packer pipeline and having an issue in getting the failure of a powershell provisioner step to fail the packer job itself. This is important as without failing the Packer job, the AMI would be published, despite the test failure.

How I'm proceeding:

• Run provisioning setup steps

• Copy Pester Script to Remote machine

• Invoke inline powershell statement to Invoke-Pester

• Download the test results from the Pester remote run

• Next provisioning step parses the file to count errors and throws error upon issue count > 0

However, even with issue count being > 0 it is not causing the pipeline to fail. Additionally some errors thrown in other provisioner steps also fail to cause the Packer job to stop. I've set $ErrorActionPreference = 'Stop' on one of them and it didn't seem to make any difference.

Here's part of the provisioning workflow for packer.

``
... {
"type": "file",
"source": "{{ template_dir }}/tests/windows-server.tests.ps1",
"destination": "{{ user TEMP_DIRECTORY }}/"
},
{
"type": "powershell",
"environment_vars": [
"TEMP_DIRECTORY={{ user TEMP_DIRECTORY }}/"
],
"inline": [
"if(-not (Get-InstalledModule Pester -MinimumVersion 4.10.1)){ Install-Module Pester -Scope AllUsers -AllowClobber -Force -verbose} ",
"Import-Module Pester -MinimumVersion 4.10.1 -Force -DisableNameChecking",
"$null = New-Item -Path $ENV:TEMP_DIRECTORY -ItemType Directory -Force -ErrorAction SilentlyContinue",
"$testresult = Invoke-Pester -Script (Join-Path $ENV:TEMP_DIRECTORY 'windows-server.tests.ps1') -OutputFile (Join-Path $ENV:TEMP_DIRECTORY 'TEST-pester-results.xml') -OutputFormat 'NUnitXML' -PassThru"
]
},
{
"type": "file",
"direction": "download",
"source": "{{ user TEMP_DIRECTORY` }}/TEST-pester-resul

After resolving some syntax issues, I found the true cause of failing to throw the error.
In my prior usage I was doing this through Inspec provisioner, which handled the exit codes.

If you are using Pester and having to do the workaround I described above, then to ensure error's in a step are thrown you need to throw an exit code other than 0.

The two steps I took that seem to work fine (I like some emoji fire in my logs )

$ErrorActionPreference = 'Stop'

try 
{
# Do code here
}
catch
{
   Write-Error " Failed to do something important `$TestFile: $TestFile"
  exit 1  # packer will recognize failure at this point
}

Note that you will want to make sure your Azure DevOps Pipeline has the following settings to publish test results regardless of failing:

# ℹ Using Invoke-Build to call Packer. You can do this with a packer extension or any other way you prefer

• task: PowerShell@2

displayName: Run Packer Configuration
inputs:
filePath: build/build.ps1
arguments: '-Task PackerBuild -Configuration $(Configuration)'
errorActionPreference: 'Continue'
pwsh: true
continueOnError: true #I want to publish the test results regardless

• task: PublishTestResults@2

displayName: Publish Pester Tests
inputs:
testResultsFormat: 'NUnit'
testResultsFiles: '**/TEST-*.xml'
condition: succeededOrFailed()

StackExchange DevOps Q#11050, answer score: 4