String as Boolean

The rule: empty strings are treated as false, not empty strings are treated as true (including strings "False").

The rule works fine in Boolean expressions:

if ($value) {...}
if (!$value) {...}

The rule works fine in cast expressions:

[bool]$value

But assigning a string to a typed variable of type [bool] may work or fail depending on invocation:

[bool]$var = $value

Scripts

Test-1.ps1 shows how empty strings work as false
Test-2.ps1 calls Test-1.ps1 and shows how assigning to [bool] may work or fail
Test-3.ps1 shows how not empty strings work as true
Test-4.ps1 calls Test-3.ps1 and shows how assigning to [bool] may work or fail