Add targeted test file option to build script

Author: bergmeister

build.ps1

@@ -30,6 +30,9 @@ param(
     [Parameter(Mandatory=$true,ParameterSetName='Test')]
     [switch] $Test,
 
+    [Parameter(ParameterSetName='Test')]
+    [string] $TestPath,
+
     [Parameter(ParameterSetName='Test')]
     [switch] $InProcess,
     [string] $WithPowerShell,
@@ -88,6 +91,7 @@ END {
         "Test" {
             $testArgs = @{
                 InProcess = $InProcess
+                TestPath = $TestPath
                 WithPowerShell = $WithPowerShell
                 Verbose = $verboseWanted
             }

build.psm1

@@ -296,6 +296,7 @@ function Test-ScriptAnalyzer
     [CmdletBinding()]
     param (
         [switch] $InProcess,
+        [string] $TestPath,
         [string] $WithPowerShell
     )
 
@@ -318,7 +319,16 @@ function Test-ScriptAnalyzer
         #
         #
         $testModulePath = Join-Path "${projectRoot}" -ChildPath out
-        $testScripts = "'${projectRoot}\Tests\Build','${projectRoot}\Tests\Engine','${projectRoot}\Tests\Rules','${projectRoot}\Tests\Documentation'"
+        if ($TestPath) {
+            $resolvedTestPath = (Resolve-Path -LiteralPath $TestPath -ErrorAction Stop).Path
+            if ((Get-Item -LiteralPath $resolvedTestPath).PSIsContainer) {
+                throw "TestPath must point to a test file."
+            }
+            $testScripts = "'{0}'" -f $resolvedTestPath.Replace("'", "''")
+        }
+        else {
+            $testScripts = "'${projectRoot}\Tests\Build','${projectRoot}\Tests\Engine','${projectRoot}\Tests\Rules','${projectRoot}\Tests\Documentation'"
+        }
         try {
             $savedModulePath = $env:PSModulePath
             $env:PSModulePath = "${testModulePath}{0}${env:PSModulePath}" -f [System.IO.Path]::PathSeparator