Script to mark '*.Tests.csproj' as C# test projects.

ConvertTestProjects.ps1

[CmdletBinding()]
param(
    [Parameter(Mandatory = $true)]
    [string]$BasePath
)

Push-Location $BasePath

$Namespace = 'http://schemas.microsoft.com/developer/msbuild/2003'
$ProjectTypeGuids = '{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}' # TestProject;C#
$TestProjectType= 'UnitTest'

Get-ChildItem .\ -Include *.Tests.csproj -Recurse |
    ForEach-Object {
        Write-Host "Processing $($_.FullName)..." -ForegroundColor DarkYellow

        $xml = [xml](Get-Content $_)
        $propertygroup = $xml.Project.PropertyGroup[0]

        if (-not $propertygroup.ProjectTypeGuids) {
            Write-Host "`t* ProjectTypeGuids element not found... Creating" -ForegroundColor DarkCyan
            $element = $xml.CreateElement('ProjectTypeGuids', $Namespace)
            $element.InnerText = $ProjectTypeGuids
            $propertygroup.AppendChild($element) | Out-Null
        }

        if (-not $propertygroup.TestProjectType) {
            Write-Host "`t* TestProjectType element not found... Creating" -ForegroundColor DarkCyan
            $element = $xml.CreateElement('TestProjectType', $Namespace)
            $element.InnerText = $TestProjectType
            $propertygroup.AppendChild($element) | Out-Null
        }

        $xml.Save($_)
    }

Pop-Location