Is it possible to execute script-containing string in script scope?

Keeping in mind the XY problem, here are my X and Y problems.

X Problem

There are PowerShell scripts, the contents of which I have obfuscated. I am still able to run the script, however.

How this is working is that the scripts are stored inside an executable. PowerShell can execute the executable, asking for a particular script by passing in that script's name as a CLI parameter. The executable's process will then forward the PowerShell script's content through stdout. PowerShell stores the stdout in a string variable, then calls Invoke-Expression, passing in the string, running the obfuscated script.

The problem is that $PSScriptRoot, when it occurs in the obfuscated scripts, is evaluated as $null.

Y Problem

When a PowerShell script, script.ps1 executes a PowerShell script as a string $scriptString, how to get $PSScriptRoot to evaluate as if it were evaluated in script.ps1.

Test 1

# script.ps1

$PSScriptRoot

# Output: Path to directory containing `script.ps1`.

This demonstrates that $PSScriptRoot is non-$null in at least one case.

Test 2

# script.ps1

Invoke-Expression '$PSScriptRoot'

# Output: Nothing

Demonstrates that the way that I am currently executing the string does not work.

Test 3

# script.ps1

. { $PSScriptRoot }

# Output: Path to directory containing `script.ps1`.

Creating a script block using the { ... } syntax does work. This requires the actual commands, however. What I have is a string containing the commands. Putting that string between the curly braces would cause commands to be output rather than run.

Test 4

# script.ps1

. [ScriptBlock]::Create('$PSScriptRoot')

# Output: Nothing

The other way to create a script block is with the C# [ScriptBlock]::Create(...) method. This actually allows creating a script block from a string. Unfortunately, it does not work.

Test 5

# script.ps1

Invoke-Command -ScriptBlock { $PSScriptRoot }

# Output: Path to directory containing `script.ps1`.

Same as test 3, except calling Invoke-Command on the script block rather than dot-sourcing the script block.

Test 6

# script.ps1

$scriptBlock = [ScriptBlock]::Create('$PSScriptRoot')
Invoke-Command -ScriptBlock $scriptBlock

# Output: Nothing.

Same as test 3, except calling Invoke-Command on the script block rather than dot-sourcing the script block.

Current belief about the problem.

• The only way that I know of to execute a string-script as a string directly is the Invoke-Expression cmdlet, which does not work. Maybe there is another way to execute a string directly which might work, but I do not know about.
• The other way to execute the string-script is to convert the string into a script block, then execute the script block. There seem to be two ways of creating a script block, one which works and one which does not work.
  • Creating a script block using the { ... } syntax seems to work, but it does not appear to work with strings.
  • Creating a script block using the [ScriptBlock]::Create(...) method does not work, but works with strings.

Questions:

• Is there a way to execute a string directly which will work without calling Invoke-Expression?
• Is there a way to create a script block from a string using the { ... } syntax?
• What is the reason/mechanism behind the test scenarios working/not working?
• Most importantly, how can we execute a string script and get $PSScriptRoot to evaluate to the proper, non-$null value?