adds Test-ChallengeFile

src/ChallengeFile/Test-ChallengeFile.ps1

@@ -0,0 +1,48 @@
+function Test-ChallengeFile {
+    <#
+    .SYNOPSIS
+        Simple path check for challenge file needed by the CredentialStores.
+
+    .DESCRIPTION
+        This is supposed to be a internal function to check the existence for a challenge file.
+
+    .PARAMETER Path
+        Specify the path to the challenge file.
+
+    .INPUTS
+        [None]
+
+    .OUTPUTS
+        [Bool].
+
+    .EXAMPLE
+        If (Test-ChallengeFile) {
+            Write-Host "The file exists."
+        }
+        Else {
+            Write-Warning "Couldn't find the given file!"
+        }
+
+    .NOTES
+        File Name   : Test-ChallengeFile.ps1
+        Author      : Marco Blessing - marco.blessing@googlemail.com
+        Requires    :
+
+    .LINK
+        https://github.com/OCram85/PSCredentialStore
+    #>
+
+    [CmdletBinding()]
+    param(
+        [Parameter(Mandatory = $false)]
+        [ValidateNotNullOrEmpty()]
+        [String]$Path = "{0}\PSCredentialStore\Challenge.bin" -f $env:ProgramData
+    )
+
+    if (Test-Path $Path) {
+        $true
+    }
+    else {
+        $false
+    }
+}