Uninstall-PSResource should not fail silently when resource was not found or prerelease criteria not met (#1898)

* initial error message

* add warnings

* add tests

* clean up comment

---------

Co-authored-by: Anam Navied <annavied@microsoft.com>

Author: anamnavi

src/code/UninstallPSResource.cs

@@ -182,6 +182,8 @@ private bool UninstallPkgHelper(out List<ErrorRecord> errRecords)
             WriteDebug("In UninstallPSResource::UninstallPkgHelper");
             var successfullyUninstalled = false;
             GetHelper getHelper = new GetHelper(this);
+
+            HashSet<string> requestedPackageNames = new HashSet<string>(Name, StringComparer.InvariantCultureIgnoreCase);
             List<string> dirsToDelete = getHelper.FilterPkgPathsByName(Name, _pathsToSearch);
             int totalDirs = dirsToDelete.Count;
             errRecords = new List<ErrorRecord>();
@@ -257,6 +259,20 @@ private bool UninstallPkgHelper(out List<ErrorRecord> errRecords)
 
                     return successfullyUninstalled;
                 }
+
+                requestedPackageNames.Remove(pkgName);
+            }
+
+            // the package requested for uninstallation was found by name, but not satisfied by version criteria (i.e version didn't exist or match prerelease criteria) so write error
+            if (requestedPackageNames.Count > 0)
+            {
+                string[] pkgsFailedToUninstall = requestedPackageNames.ToArray();
+                string prereleaseMessage = Prerelease ? "prerelease " : String.Empty;
+                string versionMessage = Version != null ? $"matching '{Version} '" : String.Empty;
+
+                string warningMessage = $"Cannot uninstall {prereleaseMessage}version(s) {versionMessage}of resource '{String.Join(", ", pkgsFailedToUninstall)}' because it does not exist.";
+
+                WriteWarning(warningMessage);
             }
 
             return successfullyUninstalled;

test/UninstallPSResourceTests/UninstallPSResource.Tests.ps1

@@ -110,6 +110,32 @@ Describe 'Test Uninstall-PSResource for Modules' -tags 'CI' {
         $pkgs.Version | Should -Not -Contain "1.0.0"
     }
 
+    It "Do not uninstall existing module when requested version does not exist and write warning instead" {
+        Uninstall-PSResource -Name $testModuleName -Version "9.9.9" -SkipDependencyCheck -WarningVariable warn -WarningAction SilentlyContinue
+
+        # Module should still be present since no prerelease versions were found
+        $res = Get-InstalledPSResource -Name $testModuleName
+        $res | Should -Not -BeNullOrEmpty
+        $res.Name | Should -Be $testModuleName
+
+        # Warning should have been written
+        $warn.Count | Should -Be 1
+        $warn[0] | Should -Match "Cannot uninstall version"
+    }
+
+    It "Do not uninstall existing module when requested version range does not exist and write warning instead" {
+        Uninstall-PSResource -Name $testModuleName -Version "[9.9.9, 10.0.0]" -SkipDependencyCheck -WarningVariable warn -WarningAction SilentlyContinue
+
+        # Module should still be present since no prerelease versions were found
+        $res = Get-InstalledPSResource -Name $testModuleName
+        $res | Should -Not -BeNullOrEmpty
+        $res.Name | Should -Be $testModuleName
+
+        # Warning should have been written
+        $warn.Count | Should -Be 1
+        $warn[0] | Should -Match "Cannot uninstall version"
+    }
+
     $testCases = @{Version="[1.0.0.0]";          ExpectedVersion="1.0.0.0"; Reason="validate version, exact match"},
                  @{Version="1.0.0.0";            ExpectedVersion="1.0.0.0"; Reason="validate version, exact match without bracket syntax"},
                  @{Version="[1.0.0.0, 5.0.0.0]"; ExpectedVersion="5.0.0.0"; Reason="validate version, exact range inclusive"},
@@ -235,6 +261,35 @@ 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" {
+        # $testModuleName (test_module2) only has stable versions installed
+        $pkg = Get-InstalledPSResource $testModuleName
+        $pkg | Should -Not -BeNullOrEmpty
+
+        # Try to uninstall with -Prerelease flag, should show warning
+        Uninstall-PSResource -Name $testModuleName -Prerelease -SkipDependencyCheck -WarningVariable warn -WarningAction SilentlyContinue
+
+        # Module should still be present since no prerelease versions were found
+        $res = Get-InstalledPSResource -Name $testModuleName
+        $res | Should -Not -BeNullOrEmpty
+        $res.Name | Should -Be $testModuleName
+        $res.Version | Should -Be $pkg.Version
+
+        # Warning should have been written
+        $warn.Count | Should -Be 1
+        $warn[0] | Should -Match "Cannot uninstall prerelease version"
+    }
+
+    It "Write warning when multiple modules are requested to be uninstalled but one does not exist" {
+        Uninstall-PSResource $testModuleName, "nonExistantModule" -SkipDependencyCheck -WarningVariable warn -WarningAction SilentlyContinue
+        $res = Get-InstalledPSResource -Name $testModuleName
+        $res | Should -BeNullOrEmpty
+
+        # Warning should have been written
+        $warn.Count | Should -Be 1
+        $warn[0] | Should -Match "Cannot uninstall version"        
+    }
+
     It "Uninstall module using -WhatIf, should not uninstall the module" {
         Start-Transcript .\testUninstallWhatIf.txt
         Uninstall-PSResource -Name $testModuleName -WhatIf -SkipDependencyCheck