with-env.ps1

function with-env {
    $originalEnvValues = @{}

    $envAssignments = @()
    $command = @()
    $isEnvAssignment = $true
    foreach ($arg in $args) {
        if ($isEnvAssignment -and $arg -match '=') {
            $envAssignments += $arg
        } else {
            $isEnvAssignment = $false
            $command += $arg
        }
    }

    foreach ($assignment in $envAssignments) {
        $envName, $envValue = $assignment -split '=', 2
        $originalEnvValues[$envName] = Get-Item "env:$envName" -ErrorAction SilentlyContinue
        Set-Item "env:$envName" $envValue
        Write-Output "With-Env: $envName => $envValue"
    }

    if ($command.Length -eq 0) {
        Write-Error "No command"
        return
    }

    try {
        & $command[0] ($command | select-object -skip 1)
    } finally {
        foreach ($envName in $originalEnvValues.Keys) {
            if ($originalEnvValues[$envName] -eq $null) {
                Remove-Item "env:$envName"
            } else {
                Set-Item "env:$envName" $originalEnvValues[$envName]
            }
        }
    }
}