Make InModuleScope-parameters available as variables in scriptblock

src/functions/InModuleScope.ps1

@@ -75,26 +75,48 @@
     )
 
     $module = Get-ScriptModule -ModuleName $ModuleName -ErrorAction Stop
+    $sessionState = Set-SessionStateHint -PassThru -Hint "Module - $($module.Name)" -SessionState $module.SessionState
 
-    # TODO: could this simply be $PSCmdlet.SessionState? Because the original scope we are moving from
-    # is the scope in which this command is running, right?
-    # $originalState = $Pester.SessionState
-    # $originalScriptBlockScope = Get-ScriptBlockScope -ScriptBlock $ScriptBlock
-
-    # try {
-    # $sessionState = Set-SessionStateHint -PassThru -Hint "Module - $($module.Name)" -SessionState $module.SessionState
-    # $Pester.SessionState = $sessionState
-    # Set-ScriptBlockScope -ScriptBlock $ScriptBlock -SessionState $sessionState
-
-    # do {
-    # Write-ScriptBlockInvocationHint -Hint "InModuleScope" -ScriptBlock $ScriptBlock
-    & $module $ScriptBlock @Parameters @ArgumentList
-    # } until ($true)
-    # }
-    # finally {
-    # $Pester.SessionState = $originalState
-    # Set-ScriptBlockScope -ScriptBlock $ScriptBlock -SessionStateInternal $originalScriptBlockScope
-    # }
+    $wrapper = {
+        param (
+            [Parameter(Mandatory = $true)]
+            [scriptblock]
+            ${Script Block},
+
+            [hashtable]
+            $___Parameters___ = @{ },
+
+            [object[]]
+            $___ArgumentList___ = @(),
+
+            [System.Management.Automation.SessionState]
+            ${Session State},
+
+            ${Set Dynamic Parameter Variable}
+        )
+
+        # This script block is used to create variables for provided parameters that
+        # the real scriptblock can inherit. Makes defining a param-block optional.
+
+        & ${Set Dynamic Parameter Variable} -SessionState ${Session State} -Parameters $___Parameters___
+
+        # define this in the current scope to be used instead of $PSBoundParameter if needed
+        # $PesterBoundParameters = if ($null -ne $___Parameters___) { $___Parameters___ } else { @{} }
+        & ${Script Block} @___Parameters___ @___ArgumentList___
+    }
+
+    Set-ScriptBlockScope -ScriptBlock $ScriptBlock -SessionState $sessionState
+    Set-ScriptBlockScope -ScriptBlock $wrapper -SessionState $sessionState
+    $splat = @{
+        'Script Block'                   = $ScriptBlock
+        '___ArgumentList___'             = $ArgumentList
+        '___Parameters___'               = $Parameters
+        'Session State'                  = $sessionState
+        'Set Dynamic Parameter Variable' = $SafeCommands['Set-DynamicParameterVariable']
+    }
+
+    Write-ScriptBlockInvocationHint -Hint "InModuleScope" -ScriptBlock $ScriptBlock
+    & $wrapper @splat
 }
 
 function Get-ScriptModule {

tst/functions/InModuleScope.Tests.ps1

@@ -84,11 +84,11 @@ Describe "Get-ScriptModule behavior" {
 }
 
 Describe 'InModuleScope parameter binding' {
-    # do not put this into BeforeAll this needs to be imported before calling InModuleScope
-    # that is below, because it requires the module to be loaded
 
-    Get-Module TestModule2 | Remove-Module
-    New-Module -Name TestModule2 { } | Import-Module -Force
+    BeforeAll {
+        Get-Module TestModule2 | Remove-Module
+        New-Module -Name TestModule2 { } | Import-Module -Force
+    }
 
     It 'Works with parameters while using advanced function/script' {
         # https://github.com/pester/Pester/issues/1809
@@ -134,9 +134,48 @@ Describe 'InModuleScope parameter binding' {
         InModuleScope -ModuleName TestModule2 -Parameters $inModuleScopeParameters -ScriptBlock $sb -ArgumentList $myArgs | Should -Be @($inModuleScopeParameters.SomeParam, $myArgs.Count)
     }
 
+    It 'Automatically imports parameters as variables in module scope' {
+        # https://github.com/pester/Pester/issues/1603
+        $inModuleScopeParameters = @{
+            SomeParam2 = 'MyValue'
+        }
+
+        $sb = {
+            "$SomeParam2"
+        }
+
+        $sb2 = {
+            # Should return nothing. Making sure dynamic variable isn't persisted in module state.
+            "$SomeParam2"
+        }
+
+        InModuleScope -ModuleName TestModule2 -ScriptBlock $sb -Parameters $inModuleScopeParameters | Should -Be $inModuleScopeParameters.SomeParam2
+        InModuleScope -ModuleName TestModule2 -ScriptBlock $sb2 | Should -BeNullOrEmpty
+    }
+
+    AfterAll {
+        Remove-Module TestModule2 -Force
+    }
+}
+
+Describe "Using variables within module scope" {
+    BeforeAll {
+        Get-Module TestModule2 | Remove-Module
+        New-Module -Name TestModule2 { } | Import-Module -Force
+    }
+
+    It 'Only script-scoped variables should persist across InModuleScope calls' {
+        $setup = {
+            $script:myVar = 'bar'
+            $myVar2 = 'bar'
+        }
+        InModuleScope -ModuleName TestModule2 -ScriptBlock $setup
+
+        InModuleScope -ModuleName TestModule2 -ScriptBlock { $script:myVar } | Should -Be 'bar'
+        InModuleScope -ModuleName TestModule2 -ScriptBlock { $myVar2 } | Should -BeNullOrEmpty
+    }
+
     AfterAll {
-        # keep this in AfterAll so we remove the module after tests are invoked
-        # and not while the tests are discovered
         Remove-Module TestModule2 -Force
     }
 }