Fix a bug where the NUnit-Report fails to generate if the test output contains Virtual Terminal Sequences

src/functions/TestResults.NUnit3.ps1

@@ -537,11 +537,27 @@
 }
 
 function Write-NUnit3OutputElement ($Output, [System.Xml.XmlWriter] $XmlWriter) {
+    # The characters in the range 0x01 to 0x19 are invalid for CData
+    # (with the exception of the characters 0x09, 0x0A and 0x0D)
+    # We convert each of these using the unicode printable version,
+    # which is obtained by adding 0x2400
+    [int]$unicodeControlPictures = 0x2400
+    [int[]]$validChars = (0x09,0x0A,0x0D)
     $outputString = @(foreach ($o in $Output) {
         if ($null -eq $o) {
             [string]::Empty
         } else {
-            $o.ToString()
+            $result = ""
+            0..($o.Length-1) |% {
+                $s = $o[$_]
+                $char = [int]$s
+                if ((0x20 -gt $char) -and (0x00 -lt $char) -and (-not ($validChars -contains $char))) {
+                    $result += [char]($char + $unicodeControlPictures)
+                } else {
+                    $result += $s
+                }
+            }
+            $result
         }
     }) -join [System.Environment]::NewLine
 

tst/Pester.RSpec.TestResults.NUnit3.ts.ps1

@@ -349,6 +349,35 @@ i -PassThru:$PassThru {
             $xmlResult.Validate({ throw $args[1].Exception })
         }
 
+        t "handles virtual terminal escape sequences" {
+            $sb = {
+                Describe 'Describe VT Sequences' {
+                    It "Successful" {
+                        $esc = [char][int]0x1B
+                        $bell = [char][int]0x07
+                        $testCases = (
+                            "$esc[32mHello`tWorld$esc[0m",
+                            "Ring the bell$bell")
+                        $testCases |% { 
+                            Write-Output $_ 
+                        }
+                        $true | Should -Be $true
+                    }
+                }
+            }
+            $r = Invoke-Pester -Configuration ([PesterConfiguration]@{ Run = @{ ScriptBlock = $sb; PassThru = $true }; Output = @{ Verbosity = 'None' } })
+
+            $xmlResult = [xml] ($r | ConvertTo-NUnitReport -Format NUnit3)
+            $xmlResult.Schemas.XmlResolver = New-Object System.Xml.XmlUrlResolver
+            $xmlResult.Schemas.Add($null, $schemaPath) > $null
+            $xmlResult.Validate({ throw $args[1].Exception })
+            $xmlDescribe = $xmlResult.'test-run'.'test-suite'.'test-suite'
+            $xmlTest = $xmlDescribe.'test-case'
+            $message = $xmlTest.output.'#cdata-section' -split "`n"
+            $message[0] | Verify-Equal "␛[32mHello`tWorld␛[0m"
+            $message[1] | Verify-Equal "Ring the bell␇"
+        }
+
         t 'should use TestResult.TestSuiteName configuration value as name-attribute for run and root Assembly test-suite' {
             $sb = {
                 Describe 'Describe' {