app.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-10.0.0.0" newVersion="10.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

HubConnectionTestsScript.ps1

# Add accept all self signed certificates
add-type @"
    using System.Net;
    using System.Security.Cryptography.X509Certificates;
    public class TrustAllCertsPolicy : ICertificatePolicy {
        public bool CheckValidationResult(
            ServicePoint srvPoint, X509Certificate certificate,
            WebRequest request, int certificateProblem) {
            return true;
        }
    }
"@
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

# Update this to where your signalR server is
$server = "https://localhost/rest/"

$dllFolder = -join((Get-Item -Path ".\" -Verbose).FullName, "\bin\Debug\")
[string[]] $dllPathsToLoad = @("\Newtonsoft.Json.dll", "\Microsoft.AspNet.SignalR.Client.dll")
$token = "insertyourtokenhere"

function LoadDllPaths($dlls)
{
	foreach ($dll in $dlls)
	{
		$dllpath = $dllFolder + $dll
		[System.Reflection.Assembly]::LoadFrom($dllpath)
	}
}

try
{
	Write-Host ""
	Write-Host "--- Loading dlls for SignalR tests ---" -ForegroundColor Magenta
	try 
	{
		LoadDllPaths($dllPathsToLoad)
		write-host "done loading" -foreground Green
	}
	catch
	{
		Write-host ([string]::Format("Error : {0}", $_.Exception.ToString())) -ForegroundColor Red
		write-host "failed" -ForegroundColor DarkRed
	}

	Write-Host ""
	write-host "--- Build HubConnection --- " -ForegroundColor Magenta
	try
	{
		$hub = New-Object Microsoft.AspNet.SignalR.Client.HubConnection($server)
		$hub.Headers["Authorization"] = -join("Bearer ", $token)
		Write-Host ([string]::Format("Created hub connection with authorization : {0}", $hub.Headers["Authorization"]))

		Start-Sleep -seconds 1
		write-host "passed" -ForegroundColor Green 
	}
	catch
	{
		Write-host ([string]::Format("Error : {0}", $_.Exception.ToString())) -ForegroundColor Red
		write-host "failed" -ForegroundColor DarkRed
	}

}
catch [System.Net.WebException]{
    Write-host ([string]::Format("Error : {0}", $_.Exception.ToString())) -ForegroundColor Red
}

write-host "Done." -ForegroundColor Magenta

packages.config

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Microsoft.AspNet.SignalR.Client" version="2.2.2" targetFramework="net452" />
  <package id="MSTest.TestAdapter" version="1.1.11" targetFramework="net452" />
  <package id="MSTest.TestFramework" version="1.1.11" targetFramework="net452" />
  <package id="Newtonsoft.Json" version="10.0.2" targetFramework="net452" />
</packages>