private/utility/Test-SqlConnection.ps1

#Taken from: https://stackoverflow.com/questions/29229109/test-database-connectivity
function Test-SqlConnection
{    
    [OutputType([bool])]
    Param
    (
        [Parameter(Mandatory=$true,
                    ValueFromPipelineByPropertyName=$true,
                    Position=0)]
        $ConnectionString
    )
    try
    {
        $sqlConnection = New-Object System.Data.SqlClient.SqlConnection $ConnectionString;
        $sqlConnection.Open();
        $sqlConnection.Close();

        return $true;
    }
    catch
    {
        return $false;
    }
}