Fix #2628: Add -LiteralPath switch to Should -Exist (#2691)

Keep default wildcard behavior (Test-Path) and add optional -LiteralPath
switch that uses Test-Path -LiteralPath for paths with special characters.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: nohwnd

src/functions/assertions/Exist.ps1

@@ -1,4 +1,4 @@
-function Should-ExistAssertion($ActualValue, [switch] $Negate, [string] $Because) {
+function Should-ExistAssertion($ActualValue, [switch] $Negate, [string] $Because, [switch] $LiteralPath) {
     <#
     .SYNOPSIS
     Does not perform any comparison, but checks if the object calling Exist is present in a PS Provider.
@@ -12,7 +12,12 @@
     `Should -Exist` calls Test-Path. Test-Path expects a file,
     returns $false because the file was removed, and fails the test.
     #>
-    [bool] $succeeded = & $SafeCommands['Test-Path'] $ActualValue
+    if ($LiteralPath) {
+        [bool] $succeeded = & $SafeCommands['Test-Path'] -LiteralPath $ActualValue
+    }
+    else {
+        [bool] $succeeded = & $SafeCommands['Test-Path'] $ActualValue
+    }
 
     if ($Negate) {
         $succeeded = -not $succeeded

tst/functions/assertions/Exist.Tests.ps1

@@ -16,6 +16,11 @@ InPesterModuleScope {
             "TestDrive:\``[test``].txt"  | Should -Exist
         }
 
+        It 'matches wildcard patterns by default' {
+            New-Item -Path "TestDrive:\wildcard1.txt" -ItemType File | Out-Null
+            "TestDrive:\wild*.txt" | Should -Exist
+        }
+
         It 'returns correct result for function drive' {
             function f1 {
             }
@@ -29,18 +34,24 @@ InPesterModuleScope {
             'env:test' | Should -Exist
         }
 
-        It 'returns correct result for env drive' {
-            $env:test = 'somevalue'
-
-            'env:test' | Should -Exist
-        }
-
         It 'returns correct assertion message' {
             $err = { 'c:\nonexistingpath' | Should -Exist -Because 'reason' } | Verify-AssertionFailed
             $err.Exception.Message | Verify-Equal "Expected path 'c:\nonexistingpath' to exist, because reason, but it did not exist."
         }
     }
 
+    Describe "Should -Exist -LiteralPath" {
+        It 'works for path with literal [ ] characters' {
+            New-Item -Path "TestDrive:\[literal].txt" -ItemType File | Out-Null
+            "TestDrive:\[literal].txt" | Should -Exist -LiteralPath
+        }
+
+        It 'does not match wildcard patterns' {
+            New-Item -Path "TestDrive:\nowild.txt" -ItemType File | Out-Null
+            "TestDrive:\no*.txt" | Should -Not -Exist -LiteralPath
+        }
+    }
+
     Describe "Should -Not -Exist" {
         It 'returns correct assertion message' {
             $currentPath = $pwd.Path