Test finder PowerShell cmdlet
Looks good.
Personally, I would take:

foreach($curPath in ($LiteralPath + $Path | Where {$_} | Resolve-Path)) {


and break out the collection generation code.
Specifically into something like:

$PathList = Join-Path $literalPath $Path | Resolve-Path 


You shouldn't need to worry about a Where-Object to validate that it isn't $null.  If there is no result it won't go up the pipeline.

If you Dot Include all of your Scripts you can wait until all are included then check your commands.  This will run anything else you have in the script though.

It may be safer to use the parser like this sample below.  In this code I looked for catch blocks to insert a breakpoint , but you could have it filter for your test prefixes too.

$ParseError = $null
$Tokens = $null
$AST = [System.Management.Automation.Language.Parser]::ParseInput($psISE.CurrentFile.Editor.Text, [ref]$Tokens, [ref]$ParseError)
if($ParseError) { 
    foreach($er in $ParseError) { Write-Error $er }
    throw "There was an error parsing script (See above). We cannot expand aliases until the script parses without errors."
}
$a = $ast.FindAll({($args[0] -is [System.Management.Automation.Language.CatchClauseAst])},$true)



Josh