$SourceFolder = "C:\Zippy"     #folder the zip was created from
$zipToTest    = "C:\zippy.zip" #the zip to test
$tempOutDir   = "C:\Tempzip"   #a temp folder used to unpack the zip to for checking

Expand-Archive -LiteralPath $zipToTest -DestinationPath $tempOutDir -force

$SRC = get-childitem -recurse -path $SourceFolder | foreach {get-filehash -path $_.FullName }

$DST = get-childitem -recurse -path $tempOutDir | foreach {get-filehash -path $_.FullName }

$SourceFolder
$SRC
write-host $SRC.count "items"
"----------"
""
$tempOutDir
$DST
write-host $DST.count "items"
"----------"
if ((Compare-Object -ReferenceObject $SRC -DifferenceObject $DST  -Property hash -PassThru).Path){
    "DIFF"
    (Compare-Object -ReferenceObject $SRC -DifferenceObject $DST  -Property hash -PassThru).Path
}
else{"ALL OK"}

Remove-Item -LiteralPath $tempOutDir -Force -Recurse