Update travis-ci script so that PRs can fail due to pester tests (#4830)

* Add a switch to force tests to fail for testing CI system to Start-PSPester
* [includeFailingTest] Add commit tag to force tests to fail for testing CI system

build.psm1

@@ -843,9 +843,15 @@ function Start-PSPester {
         [switch]$Unelevate,
         [switch]$Quiet,
         [Parameter(ParameterSetName='PassThru',Mandatory=$true)]
-        [switch]$PassThru
+        [switch]$PassThru,
+        [switch]$IncludeFailingTest
     )
 
+    if ($IncludeFailingTest.IsPresent)
+    {
+        $Path += "$PSScriptRoot/tools/failingTests"
+    }
+    
     # we need to do few checks and if user didn't provide $ExcludeTag explicitly, we should alternate the default
     if ($Unelevate)
     {
@@ -1079,14 +1085,17 @@ function Test-PSPesterResults
     {
         if ($ResultObject.TotalCount -le 0)
         {
-            logerror 'NO TESTS RUN'
+            throw 'NO TESTS RUN'
         }
         elseif ($ResultObject.FailedCount -gt 0)
         {
             logerror 'TEST FAILURES'
+
             $ResultObject.TestResult | Where-Object {$_.Passed -eq $false} | ForEach-Object {
                 Show-PSPesterError -testFailureObject $_
             }
+
+            throw "$($ResultObject.FailedCount) tests in $TestArea failed"
         }
     }
 }

tools/failingTests/fail.tests.ps1

@@ -0,0 +1,5 @@
+Describe "Failing test used to test CI Scripts" -Tags 'CI' {
+    It "Should fail" {
+        1 | should be 2
+    }
+}

tools/travis.ps1

@@ -114,6 +114,7 @@ else
 
 # Run a full build if the build was trigger via cron, api or the commit message contains `[Feature]`
 $hasFeatureTag = $commitMessage -match '\[feature\]'
+$hasRunFailingTestTag = $commitMessage -match '\[includeFailingTest\]'
 $isDailyBuild = $env:TRAVIS_EVENT_TYPE -eq 'cron' -or $env:TRAVIS_EVENT_TYPE -eq 'api'
 # only update the build badge for the cron job
 $cronBuild = $env:TRAVIS_EVENT_TYPE -eq 'cron'
@@ -167,6 +168,11 @@ else
         $pesterParam['ThrowOnFailure'] = $true
     }
 
+    if ($hasRunFailingTestTag)
+    {
+        $pesterParam['IncludeFailingTest'] = $true
+    }
+
     # Remove telemetry semaphore file in CI
     $telemetrySemaphoreFilepath = Join-Path $output DELETE_ME_TO_DISABLE_CONSOLEHOST_TELEMETRY
     if ( Test-Path "${telemetrySemaphoreFilepath}" ) {