Add warning when uninstall fails due to version/prerelease filters

Co-authored-by: alerickson <25858831+alerickson@users.noreply.github.com>

Author: Copilot

src/code/UninstallPSResource.cs

@@ -258,6 +258,23 @@ private bool UninstallPkgHelper(out List<ErrorRecord> errRecords)
                 }
             }
 
+            // If we had packages but didn't uninstall any (e.g., due to version/prerelease filters), write a warning
+            if (currentUninstalledDirCount == 0 && totalDirs > 0)
+            {
+                string warningMessage = Prerelease 
+                    ? $"No prerelease versions of '{String.Join(", ", Name)}' were found to uninstall."
+                    : $"No packages matching the specified criteria for '{String.Join(", ", Name)}' were found to uninstall.";
+                
+                if (Version != null && !Version.Trim().Equals("*"))
+                {
+                    warningMessage = Prerelease 
+                        ? $"No prerelease versions of '{String.Join(", ", Name)}' matching version '{Version}' were found to uninstall."
+                        : $"No packages of '{String.Join(", ", Name)}' matching version '{Version}' were found to uninstall.";
+                }
+
+                WriteWarning(warningMessage);
+            }
+
             return successfullyUninstalled;
         }
 

test/UninstallPSResourceTests/UninstallPSResource.Tests.ps1

@@ -235,6 +235,23 @@ Describe 'Test Uninstall-PSResource for Modules' -tags 'CI' {
         $stableVersionPkgs.Count | Should -Be 2
     }
 
+    It "Write warning when using -Prerelease flag with only stable versions installed" {
+        # Install a stable version
+        Install-PSResource -Name $testModuleName -Version "5.0.0.0" -Repository $PSGalleryName -TrustRepository
+        
+        # Try to uninstall with -Prerelease flag, should show warning
+        Uninstall-PSResource -Name $testModuleName -Prerelease -SkipDependencyCheck -WarningVariable warn -WarningAction SilentlyContinue
+        
+        # Module should still be present
+        $res = Get-InstalledPSResource -Name $testModuleName -Version "5.0.0.0"
+        $res.Name | Should -Be $testModuleName
+        $res.Version | Should -Be "5.0.0.0"
+        
+        # Warning should have been written
+        $warn.Count | Should -Be 1
+        $warn[0] | Should -Match "No prerelease versions"
+    }
+
     It "Uninstall module using -WhatIf, should not uninstall the module" {
         Start-Transcript .\testUninstallWhatIf.txt
         Uninstall-PSResource -Name $testModuleName -WhatIf -SkipDependencyCheck