Testing Custom Validators and Transforms

Output.txt

VERBOSE: Loading module from path 'C:\Custom Validators and Transforms\TestMod.psm1'.
VERBOSE: Exporting function 'Test-OwnClass'.
VERBOSE: Exporting function 'Test-ValidatePathExists'.
VERBOSE: Exporting function 'Test-PathTransform'.
VERBOSE: Importing function 'Test-OwnClass'.
VERBOSE: Importing function 'Test-PathTransform'.
VERBOSE: Importing function 'Test-ValidatePathExists'.

SomeString
----------
Some test string
Cannot find the type for custom attribute 'ValidatePathExists'. Make sure that the assembly that contains this type is loaded.
At C:\Custom Validators and Transforms\TestMod.psm1:69 char:9
+         [ValidatePathExists()]
+         ~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: ([ValidatePathExists()]:AttributeAst) [], RuntimeException
    + FullyQualifiedErrorId : CustomAttributeTypeNotFound

Cannot find the type for custom attribute 'PathTransform'. Make sure that the assembly that contains this type is loaded.
At C:\Custom Validators and Transforms\TestMod.psm1:80 char:9
+         [PathTransform()]
+         ~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: ([PathTransform()]:AttributeAst) [], RuntimeException
    + FullyQualifiedErrorId : CustomAttributeTypeNotFound

Test.ps1

$module = [System.IO.Path]::Combine($PSScriptRoot, 'TestMod.psm1')

Import-Module -Name $module -Force -Verbose

Test-OwnClass -String 'Some test string'
Test-ValidatePathExists -Path $module
Test-PathTransform -Path $module

TestMod.psm1

class OwnClass
{
    [string] $SomeString

    OwnClass ([string] $String)
    {
        $this.SomeString = $String
    }
}


class ValidatePathExistsAttribute : System.Management.Automation.ValidateArgumentsAttribute
{
    [void]  Validate([object]$arguments, [System.Management.Automation.EngineIntrinsics]$engineIntrinsics)
    {
        $path = $arguments
        if([string]::IsNullOrWhiteSpace($path))
        {
            Throw [System.ArgumentNullException]::new()
        }
        if(-not (Test-Path -Path $path))
        {
            Throw [System.IO.FileNotFoundException]::new()
        }        
    }
}


class PathTransformAttribute : System.Management.Automation.ArgumentTransformationAttribute
{
    [object] Transform([System.Management.Automation.EngineIntrinsics]$engineIntrinsics, [object] $inputData)
    {
        if ( $inputData -is [string] )
        {
            if ( -NOT [string]::IsNullOrWhiteSpace( $inputData ) )
            {
                $fullPath = Resolve-Path -Path $inputData -ErrorAction SilentlyContinue
                if ( ( $fullPath.count -gt 0 ) -and ( -Not [string]::IsNullOrWhiteSpace( $fullPath ) ) )
                {
                    return $fullPath.Path
                }
            }
        }
        $fullName = $inputData.Fullname
        if($fullName.count -gt 0)
        {
            return $fullName
        }

        throw [System.IO.FileNotFoundException]::new()
    }
}


function Test-OwnClass {
    Param(
        [OwnClass] $String
    )

    $String
}


function Test-ValidatePathExists {
    Param(
        [Parameter(Mandatory)]
        [ValidatePathExists()]
        $Path
    )

    $Path
}


function Test-PathTransform {
    Param(
        [Parameter(Mandatory)]
        [PathTransform()]
        $Path
    )

    $Path
}