Ast parsing

Functions/Mock.Tests.ps1

@@ -2103,7 +2103,15 @@ if ($PSVersionTable.PSVersion.Major -ge 3) {
                 It 'returns default mock' {
                     Get-Content -Path "c:\temp.txt" | Should -Be "default-get-content"
                 }
+            }
+
+            Context "Alias rewriting works when alias and parameter name differ in length" {
+
+                Mock New-Item { return "nic" } -ParameterFilter { $Type -ne $null -and $Type.StartsWith("nic") }
 
+                It 'calls the mock' {
+                    New-Item -Path 'Hello' -Type "nic" | Should -Be "nic"
+                }
             }
 
             if ($PSVersionTable.PSVersion -ge 5.1) {
@@ -2121,7 +2129,7 @@ if ($PSVersionTable.PSVersion.Major -ge 3) {
         }
 
         Context 'Assert-MockCalled' {
-            It "Uses parameter aliases in Parameter-Filter" {
+            It "Uses parameter aliases in ParameterFilter" {
                 function f { Get-Content -Path 'temp.txt' -Tail 10 }
                 Mock Get-Content { }
 
@@ -2207,3 +2215,8 @@ Describe "Mock definition output" {
         $output | Should -Be $null
     }
 }
+
+Describe 'Mocking using ParameterFilter with scriptblock' {
+    $filter = [scriptblock]::Create( ('$Path -eq ''C:\Windows''') )
+    Mock -CommandName 'Test-Path' -ParameterFilter $filter
+}

Functions/Mock.ps1

@@ -1615,26 +1615,26 @@ function New-BlockWithoutParameterAliases {
     try {
         if ($PSVersionTable.PSVersion.Major -ge 3) {
             $params = $Metadata.Parameters.Values
-            $ast = $Block.Ast
+            $ast = $Block.Ast.EndBlock
             $blockText = $ast.Extent.Text
-            $variables = $Ast.FindAll( { param($ast) $ast -is [System.Management.Automation.Language.VariableExpressionAst]}, $true)
+            $variables = [array]($Ast.FindAll( { param($ast) $ast -is [System.Management.Automation.Language.VariableExpressionAst]}, $true))
+            [array]::Reverse($variables)
 
             foreach ($var in $variables) {
                 $varName = $var.VariablePath.UserPath
                 $length = $varName.Length
 
                 foreach ($param in $params) {
                     if ($param.Aliases -contains $varName) {
-                        $startIndex = $var.Extent.StartOffset - $block.Ast.Extent.StartOffset + 1
+                        $startIndex = $var.Extent.StartOffset - $ast.Extent.StartOffset + 1 # move one position after the dollar sign
 
                         $blockText = $blockText.Remove($startIndex, $length).Insert($startIndex, $param.Name)
+
+                        break # It is safe to stop checking for further params here, since aliases cannot be shared by parameters
                     }
                 }
             }
 
-            # Remove top-level brackets {}
-            $blockText = $blockText.Remove($blockText.Length - 1, 1).Remove(0, 1)
-
             $Block = [scriptblock]::Create($blockText)
         }