fix: preserve selections when config import is invalid

functions/private/Update-WinUtilSelections.ps1

@@ -1,4 +1,19 @@
-function Update-WinUtilSelections ($flatJson) {
+function Update-WinUtilSelections {
+    param(
+        [Parameter(Mandatory)]
+        [string[]]$flatJson,
+
+        [switch]$Replace
+    )
+
+    $nextSelections = @{
+        selectedApps     = [System.Collections.Generic.List[string]]::new()
+        selectedTweaks   = [System.Collections.Generic.List[string]]::new()
+        selectedToggles  = [System.Collections.Generic.List[string]]::new()
+        selectedFeatures = [System.Collections.Generic.List[string]]::new()
+        selectedAppx     = [System.Collections.Generic.List[string]]::new()
+    }
+
     foreach ($cbkey in $flatJson) {
 
         $listName = switch -Regex ($cbkey) {
@@ -9,6 +24,45 @@ function Update-WinUtilSelections ($flatJson) {
             '^WPFAppx'    { 'selectedAppx' }
         }
 
-        $sync.$listName.Add($cbkey)
+        if (-not $listName) {
+            throw "Unsupported selection key '$cbkey'."
+        }
+
+        $isKnownSelection = switch ($listName) {
+            'selectedApps' {
+                $sync.configs.applicationsHashtable.ContainsKey($cbkey)
+            }
+            'selectedTweaks' {
+                $null -ne $sync.configs.tweaks.PSObject.Properties[$cbkey]
+            }
+            'selectedToggles' {
+                $null -ne $sync.configs.tweaks.PSObject.Properties[$cbkey]
+            }
+            'selectedFeatures' {
+                $null -ne $sync.configs.feature.PSObject.Properties[$cbkey]
+            }
+            'selectedAppx' {
+                $sync.configs.appxHashtable.ContainsKey($cbkey)
+            }
+        }
+
+        if (-not $isKnownSelection) {
+            throw "Unknown selection key '$cbkey'."
+        }
+
+        $nextSelections[$listName].Add($cbkey)
+    }
+
+    if ($Replace) {
+        foreach ($listName in $nextSelections.Keys) {
+            $sync[$listName] = $nextSelections[$listName]
+        }
+        return
+    }
+
+    foreach ($listName in $nextSelections.Keys) {
+        foreach ($cbkey in $nextSelections[$listName]) {
+            $sync.$listName.Add($cbkey)
+        }
     }
 }

functions/public/Invoke-WPFImpex.ps1

@@ -84,15 +84,9 @@ function Invoke-WPFImpex {
                         return
                     }
 
-                    # Clear all existing selections before importing so the import replaces
-                    # the current state rather than merging with it
-                    $sync.selectedAppx = [System.Collections.Generic.List[string]]::new()
-                    $sync.selectedApps = [System.Collections.Generic.List[string]]::new()
-                    $sync.selectedTweaks = [System.Collections.Generic.List[string]]::new()
-                    $sync.selectedToggles = [System.Collections.Generic.List[string]]::new()
-                    $sync.selectedFeatures = [System.Collections.Generic.List[string]]::new()
-
-                    Update-WinUtilSelections -flatJson $flattenedJson
+                    # Build and validate every imported selection before replacing the current
+                    # state. This keeps a malformed config from leaving partial selections behind.
+                    Update-WinUtilSelections -flatJson $flattenedJson -Replace
 
                     if ($sync.Form) {
                         Reset-WPFCheckBoxes -doToggles $true

pester/ui-state.Tests.ps1

@@ -48,19 +48,25 @@ namespace System.Windows.Controls
 
     public class WrapPanel
     {
-        public global::Windows.Visibility Visibility { get; set; }
+        public object Visibility { get; set; }
     }
 
     public class StackPanel
     {
-        public System.Collections.ArrayList Children { get; } = new System.Collections.ArrayList();
+        public System.Collections.ArrayList Children { get; private set; }
+
+        public StackPanel()
+        {
+            Children = new System.Collections.ArrayList();
+        }
     }
 }
 "@
     }
 
     . (Join-Path $script:repoRoot "functions\private\Update-WinUtilSelections.ps1")
     . (Join-Path $script:repoRoot "functions\private\Reset-WPFCheckBoxes.ps1")
+    . (Join-Path $script:repoRoot "functions\public\Invoke-WPFImpex.ps1")
     . (Join-Path $script:repoRoot "functions\public\Invoke-WPFGetInstalled.ps1")
     . (Join-Path $script:repoRoot "functions\public\Invoke-WPFSelectedCheckboxesUpdate.ps1")
     . (Join-Path $script:repoRoot "functions\public\Invoke-WPFButton.ps1")
@@ -127,6 +133,16 @@ namespace System.Windows.Controls
                         Content = "Git"
                     }
                 }
+                appxHashtable = @{
+                    WPFAppxExample = [pscustomobject]@{}
+                }
+                tweaks = [pscustomobject]@{
+                    WPFTweaksTelemetry = [pscustomobject]@{}
+                    WPFToggleDarkMode = [pscustomobject]@{}
+                }
+                feature = [pscustomobject]@{
+                    WPFFeatureSandbox = [pscustomobject]@{}
+                }
             }
             WPFselectedAppsButton = [pscustomobject]@{
                 Content = ""
@@ -174,6 +190,106 @@ Describe "Update-WinUtilSelections" {
         @($script:sync.selectedFeatures) | Should -Be @("WPFFeatureSandbox")
         @($script:sync.selectedAppx) | Should -Be @("WPFAppxExample")
     }
+
+    It "replaces selections only after every imported key is validated" {
+        $script:sync.selectedApps.Add("WPFInstallExisting")
+        $script:sync.selectedTweaks.Add("WPFTweaksExisting")
+
+        Update-WinUtilSelections -flatJson @(
+            "WPFInstallGit",
+            "WPFFeatureSandbox"
+        ) -Replace
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallGit")
+        @($script:sync.selectedTweaks) | Should -Be @()
+        @($script:sync.selectedFeatures) | Should -Be @("WPFFeatureSandbox")
+    }
+
+    It "preserves existing selections when an imported key is unsupported" {
+        $script:sync.selectedApps.Add("WPFInstallExisting")
+        $script:sync.selectedTweaks.Add("WPFTweaksExisting")
+
+        {
+            Update-WinUtilSelections -flatJson @(
+                "WPFInstallGit",
+                "NotAWinUtilKey"
+            ) -Replace
+        } | Should -Throw "Unsupported selection key 'NotAWinUtilKey'."
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallExisting")
+        @($script:sync.selectedTweaks) | Should -Be @("WPFTweaksExisting")
+        @($script:sync.selectedFeatures) | Should -Be @()
+    }
+
+    It "preserves existing selections when an imported key is not in the current catalog" {
+        $script:sync.selectedApps.Add("WPFInstallExisting")
+
+        {
+            Update-WinUtilSelections -flatJson @(
+                "WPFInstallGit",
+                "WPFInstallUnknown"
+            ) -Replace
+        } | Should -Throw "Unknown selection key 'WPFInstallUnknown'."
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallExisting")
+        @($script:sync.selectedTweaks) | Should -Be @()
+        @($script:sync.selectedFeatures) | Should -Be @()
+    }
+}
+
+Describe "Invoke-WPFImpex import selection state" {
+    BeforeEach {
+        New-WinUtilUiStateTestContext
+        $script:sync.Form = [pscustomobject]@{}
+
+        Mock Reset-WPFCheckBoxes { }
+        Mock Write-Error { }
+    }
+
+    AfterEach {
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name sync -Scope Global -ErrorAction SilentlyContinue
+    }
+
+    It "replaces selections and resets the UI after a valid import" {
+        $script:sync.selectedApps.Add("WPFInstallExisting")
+        $script:sync.selectedTweaks.Add("WPFTweaksExisting")
+        $configPath = Join-Path $TestDrive "valid-config.json"
+        @(
+            "WPFInstallGit",
+            "WPFFeatureSandbox"
+        ) | ConvertTo-Json | Set-Content -LiteralPath $configPath
+
+        Invoke-WPFImpex -type "import" -Config $configPath
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallGit")
+        @($script:sync.selectedTweaks) | Should -Be @()
+        @($script:sync.selectedFeatures) | Should -Be @("WPFFeatureSandbox")
+        Should -Invoke -CommandName Reset-WPFCheckBoxes -Times 1 -Exactly -ParameterFilter {
+            $doToggles -eq $true
+        }
+        Should -Invoke -CommandName Write-Error -Times 0 -Exactly
+    }
+
+    It "preserves selections and does not reset the UI after an invalid import" {
+        $script:sync.selectedApps.Add("WPFInstallExisting")
+        $script:sync.selectedTweaks.Add("WPFTweaksExisting")
+        $configPath = Join-Path $TestDrive "invalid-config.json"
+        @(
+            "WPFInstallGit",
+            "WPFInstallUnknown"
+        ) | ConvertTo-Json | Set-Content -LiteralPath $configPath
+
+        Invoke-WPFImpex -type "import" -Config $configPath
+
+        @($script:sync.selectedApps) | Should -Be @("WPFInstallExisting")
+        @($script:sync.selectedTweaks) | Should -Be @("WPFTweaksExisting")
+        @($script:sync.selectedFeatures) | Should -Be @()
+        Should -Invoke -CommandName Reset-WPFCheckBoxes -Times 0 -Exactly
+        Should -Invoke -CommandName Write-Error -Times 1 -Exactly -ParameterFilter {
+            $Message -like "An error occurred while importing: *Unknown selection key 'WPFInstallUnknown'.*"
+        }
+    }
 }
 
 Describe "Invoke-WPFSelectedCheckboxesUpdate" {