Helper module that helps emulate the Azure Functions environment in a PowerShell session.

AzFuncEnvironment.psm1

<#

Helper module that helps emulate the Azure Functions environment in a PowerShell session. It do so by:

1. Modifying the PSModulePath
2. Loading Azure Functions DLLs so custom types are available
3. Setting up TypeForwards for the Http*Context types since the Azure Functions runtime does this

Usage:

# To do all of that ^
Enable-AzFuncEnvironment

# To change the PSModulePath back
Disable-AzFuncEnvironment

#>

$script:OldPSModulePath = $env:PSModulePath
$script:PathSeparator = [System.IO.Path]::PathSeparator

# TODO: figure out where chocolatey installs it and make cross-plat
$script:PowerShellWorkerPath = "C:\Users\tyleonha\AppData\Roaming\npm\node_modules\azure-functions-core-tools\bin\workers\powershell"

function Enable-AzFuncEnvironment {
    [CmdletBinding()]
    param (
        $Path = '.',
        [switch]
        $NoDllLoad
    )
    # Move to the Path
    $Path = Push-Location $Path -PassThru -ErrorAction Stop
    
    if (!(Join-Path $Path host.json | Test-Path)) {
        Pop-Location
        throw "Path doesn't seem to contain an Azure Function App: $($Path.Path)"
    }

    # Build the PSModulePath
    $newPSModulePath = Join-Path $Path.Path ([System.IO.Path]::DirectorySeparatorChar) "Modules" $script:PathSeparator

    $hostJson = Get-Content .\host.json -Raw | ConvertFrom-Json
    if($hostJson.managedDependency.enabled) {
        $functionAppName = [System.IO.Path]::GetFileName($Path.Path)
        # TODO: make cross-plat
        $newPSModulePath += "C:\Users\tyleonha\AppData\Local\AzureFunctions\$functionAppName\ManagedDependencies$script:PathSeparator"
    }

    $newPSModulePath += "$script:PowerShellWorkerPath\Modules$script:PathSeparator"
    
    # We still need to keep the VSCode built-in modules in the PSModulePath so things like Script Analysis still works.
    if ($host.Name -eq "Visual Studio Code Host") {
        $newPSModulePath += $env:PSModulePath -split $script:PathSeparator | Select-Object -Last 1
    }

    $script:OldPSModulePath = $env:PSModulePath
    $env:PSModulePath = $newPSModulePath

    # Load the PowerShell Worker DLL and add accelerators 
    if(!$NoDllLoad) {
        Add-Type -Path "$script:PowerShellWorkerPath/Microsoft.Azure.Functions.PowerShellWorker.dll"

        $addMethod = [psobject].Assembly.GetType("System.Management.Automation.TypeAccelerators").GetMethod("Add", [type[]]@([string], [type]))
        $addMethod.Invoke($null, @("HttpResponseContext", [Microsoft.Azure.Functions.PowerShellWorker.HttpResponseContext]))
        $addMethod.Invoke($null, @("HttpRequestContext", [Microsoft.Azure.Functions.PowerShellWorker.HttpRequestContext]))
    }
}

function Disable-AzFuncEnvironment {
    [CmdletBinding()]
    param ()

    Write-Warning 'Assembly unloading is not possible in .NET Core so the state can''t be cleaned up completely. If you need a full cleanup, restart your PowerShell instance.'
    Pop-Location
    $env:PSModulePath = $script:OldPSModulePath
}

Export-ModuleMember -Function Enable-AzFuncEnvironment,Disable-AzFuncEnvironment