(maint) Output choco pack failures

This adds logic to the Invoke-Tests file to output if a package failed
fail to pack. This allows for improved developer experience by
indicating if packages fail to build. This also allows impromptu
improvement to the developer experience by allowing simple changes to
the script to throw in place of outputting an errorand thus not
allowing tests to run without the full set of test packages.

Author: corbob

Invoke-Tests.ps1

@@ -57,10 +57,30 @@ if (-not (Test-Path "$TestPath/packages") -or -not $SkipPackaging) {
     $nuspecs = Get-ChildItem -Path $PSScriptRoot/src/chocolatey.tests.integration, $PSScriptRoot/tests/packages -Recurse -Include *.nuspec | Where-Object FullName -NotMatch 'bin'
     Get-ChildItem -Path $PSScriptRoot/tests/packages -Recurse -Include *.nupkg | Copy-Item -Destination "$TestPath/packages"
 
-    foreach ($file in $nuspecs) {
-        Write-Host "Packaging $file"
+    $packFailures = foreach ($file in $nuspecs) {
         # Include allow-unofficial in case an unofficial Chocolatey has been installed globally for testing
-        $null = choco pack $file.FullName --out "$TestPath/packages" --allow-unofficial
+        $packOutput = choco pack $file.FullName --out "$TestPath/packages" --allow-unofficial
+        if ($LASTEXITCODE -ne 0) {
+            [pscustomobject]@{
+                Package = $file.FullName
+                ExitCode = $LASTEXITCODE
+                Output = $packOutput
+            }
+            Write-Warning "Failed to pack $file"
+        }
+        else {
+            Write-Host "Packaged $file"
+        }
+    }
+
+    if ($null -ne $packFailures) {
+        foreach ($failure in $packFailures) {
+            Write-Warning "$($failure.Package) failed to pack with exit code: $($failure.ExitCode)"
+            $failure.Output | Write-Warning
+        }
+        # If you want to stop things, change this to a throw.
+        # This is not currently throwing as there are two packages that are supposed to fail.
+        Write-Error "$($packFailures.Count) packages failed to pack."
     }
 }