Fix PSScriptAnalyzer warnings and test IsWindows from module scope

Author: MariusStorhaug

src/tests/Module/PSModule/PSModule.Tests.ps1

@@ -37,7 +37,6 @@ BeforeAll {
             $expectedEnumNames = [regex]::Matches($Matches[1], '\[([^\]]+)\]') | ForEach-Object { $_.Groups[1].Value }
         }
     }
-    $expectedTypeNames = @($expectedEnumNames) + @($expectedClassNames) | Where-Object { $_ }
     Write-Host "Has class exporter: $hasClassExporter"
     Write-Host "Expected classes: $($expectedClassNames -join ', ')"
     Write-Host "Expected enums: $($expectedEnumNames -join ', ')"
@@ -64,33 +63,31 @@ Describe 'PSModule - Module tests' {
     }
 
     Context 'Framework - IsWindows compatibility shim' {
-        It 'Should have $IsWindows defined' {
+        It 'Should have $IsWindows defined in the module scope' {
             # The framework injects "$IsWindows = $true" for PowerShell 5.1 (Desktop edition).
             # On PS 7+ (Core), $IsWindows is a built-in automatic variable.
-            # Either way, it must be defined after module import.
-            $variable = Get-Variable -Name 'IsWindows' -ErrorAction SilentlyContinue
-            $variable | Should -Not -BeNullOrEmpty -Because 'the framework injects a compatibility shim for PS 5.1'
+            # The variable is set inside the module scope and is not exported, so we must check from within the module.
+            $isWindowsDefined = & (Get-Module $moduleName) { Get-Variable -Name 'IsWindows' -ErrorAction SilentlyContinue }
+            $isWindowsDefined | Should -Not -BeNullOrEmpty -Because 'the framework injects a compatibility shim for PS 5.1'
         }
     }
 
     Context 'Framework - Type accelerator registration' -Skip:(-not $hasClassExporter) {
-        BeforeAll {
-            $typeAccelerators = [psobject].Assembly.GetType('System.Management.Automation.TypeAccelerators')::Get
-        }
-
         It 'Should register public enum [<_>] as a type accelerator' -ForEach $expectedEnumNames {
-            $typeAccelerators.Keys | Should -Contain $_ -Because 'the framework registers public enums as type accelerators'
+            $registered = [psobject].Assembly.GetType('System.Management.Automation.TypeAccelerators')::Get
+            $registered.Keys | Should -Contain $_ -Because 'the framework registers public enums as type accelerators'
         }
 
         It 'Should register public class [<_>] as a type accelerator' -ForEach $expectedClassNames {
-            $typeAccelerators.Keys | Should -Contain $_ -Because 'the framework registers public classes as type accelerators'
+            $registered = [psobject].Assembly.GetType('System.Management.Automation.TypeAccelerators')::Get
+            $registered.Keys | Should -Contain $_ -Because 'the framework registers public classes as type accelerators'
         }
     }
 
     Context 'Framework - Module OnRemove cleanup' -Skip:(-not $hasClassExporter) {
         It 'Should clean up type accelerators when the module is removed' {
             # Capture type names before removal
-            $typeNames = $expectedTypeNames.Clone()
+            $typeNames = @(@($expectedEnumNames) + @($expectedClassNames) | Where-Object { $_ })
             $typeNames | Should -Not -BeNullOrEmpty -Because 'there should be types to verify cleanup for'
 
             # Remove the module to trigger the OnRemove hook