Mock-WebCmdletCertificateAuth.ps1

class MockedWebResponseAsyncResult : System.IAsyncResult {
    [System.Net.WebRequest] $Request;
    [Object]$state

    MockedWebResponseAsyncResult([System.Net.WebRequest] $request, [object]$State) {
        $this.Request = $request
        $This.State = $State
    }

    [bool] get_IsCompleted () {
        return $true
    }

    [System.Threading.WaitHandle] get_AsyncWaitHandle () {
        return [System.Threading.ManualResetEvent]::new($true)
    }

    [Object] get_AsyncState () {
        return $this.State
    }

    [bool] get_CompletedSynchronously () {
        return $true
    }
}

Class CertificateAuthenticationResponse : System.Net.WebResponse {
    [system.io.stream]$responseStream
    [int64]$ContentLength
    [System.Net.WebHeaderCollection]$Headers

    CertificateAuthenticationResponse ([system.io.stream]$responseStream){
        $this.responseStream = $responseStream
        $This.ContentLength = $responseStream.Length
        $This.Headers  = [System.Net.WebHeaderCollection]::New()
        $This.Headers.add("Content-Encoding",'UTF8')
    }

   [system.io.stream] GetResponseStream(){
        return $this.responseStream
    }

    [int64] get_ContentLength(){
        return $this.ContentLength
    }

    [System.Net.WebHeaderCollection] get_Headers(){
        return $This.Headers
    }
}

Class CertificateAuthenticationRequest : System.Net.WebRequest {
    [system.io.MemoryStream]$requestStream = [system.io.MemoryStream]::new()
    [system.io.MemoryStream]$responseStream
    [string]$Method
    [string]$ContentType
    [Int64]$ContentLength
    static [Uri]$_requestUri

     CertificateAuthenticationRequest ([string]$Response){
        $this.responseStream = [system.io.MemoryStream]::new(([System.Text.Encoding]::UTF8.GetBytes($response)))

    }

    [string] ContentAsString()
    {
        return [System.Text.Encoding]::UTF8.GetString($this.requestStream.ToArray());
    }

    [System.Io.Stream] GetRequestStream() {
        return $this.requestStream
    }

    [System.Net.WebResponse] GetResponse(){
        return [CertificateAuthenticationResponse]::new($this.responseStream)
    }
    
    [int64] get_ContentLength(){
        return $this.ContentLength
    }
    
    [void]set_ContentLength([Int64]$value){
        $this.ContentLength = $Value
    }

    [String] get_Method(){
        return $this.Method
    }
    
    [void]set_Method([string]$value){
        $this.Method = $Value
    }

    [System.Uri] get_RequestUri() {
        return [CertificateAuthenticationRequest]::_requestUri
    }

    [IAsyncResult] BeginGetResponse([AsyncCallback]$callback, [object]$state) {
        $Task = [MockedWebResponseAsyncResult]::new($this,$state)
        $callback.Invoke($Task)
        return $Task
    }

    [system.net.WebResponse] EndGetResponse( [IAsyncResult]$asyncResult ){
        return $This.GetResponse()
    }
}

Class CertificateAuthenticationRequestCreate : System.Net.IWebRequestCreate {
    static [System.Net.WebRequest]$nextRequest
    static [object]$lockObject = [object]::New()
    [System.Net.WebRequest] Create ([uri]$Uri){
        [CertificateAuthenticationRequest]::_requestUri = $Uri
        return [CertificateAuthenticationRequestCreate]::nextRequest
    }
    
    static [CertificateAuthenticationRequest]  CreateCertificateAuthenticationRequest([string]$response){
        $request  = [CertificateAuthenticationRequest]::new($response)
        [CertificateAuthenticationRequestCreate]::nextRequest = $request 
        return $request 
    }

    CertificateAuthenticationRequestCreate () {}
}

$null = [System.Net.WebRequest]::RegisterPrefix("test", [CertificateAuthenticationRequestCreate]::new())
$request = [CertificateAuthenticationRequestCreate]::CreateCertificateAuthenticationRequest('testy')

Invoke-WebRequest -Uri 'test://myurl'
$MyError = $Error[0] 
$MyError | fl * -force
$MyError.Exception | fl * -force
$MyError.Exception.InnerException | fl * -force
Read-Host 'exit'