Add localization framework for the GUI (en-US baseline) (#764)

Credit to @jmolinap2 for their work in #643, which was used as inspiration.

Tests/Confirm-UnsafeAppRemoval.Tests.ps1

@@ -1,6 +1,10 @@
 BeforeAll {
     function Show-MessageBox { param($Message, $Title, $Button, $Icon, $Owner) 'Yes' }
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Confirm-UnsafeAppRemoval.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Confirm-UnsafeAppRemoval' {

Tests/Get-FriendlyRegistryBackupTarget.Tests.ps1

@@ -1,6 +1,10 @@
 BeforeAll {
     $friendlyTargetScriptPath = Join-Path $PSScriptRoot '..\Scripts\Helpers\Get-FriendlyRegistryBackupTarget.ps1'
     . $friendlyTargetScriptPath
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Get-FriendlyRegistryBackupTarget' {

Tests/Get-RebootFeatureLabels.Tests.ps1

@@ -1,6 +1,29 @@
 BeforeAll {
     $rebootFeatureLabelsScriptPath = Join-Path $PSScriptRoot '..\Scripts\Helpers\Get-RebootFeatureLabels.ps1'
     . $rebootFeatureLabelsScriptPath
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
+
+    # Builds a $script:Lang fixture whose Features section mirrors $script:Features exactly,
+    # so Get-Translation resolves the same Label/UndoLabel text the test's fake FeatureIds expect.
+    function Sync-TestLangFeatures {
+        $langFeatures = @{}
+        foreach ($featureId in $script:Features.Keys) {
+            $feature = $script:Features[$featureId]
+            $entry = @{}
+            foreach ($field in 'Label', 'UndoLabel') {
+                if ($null -ne $feature.$field) { $entry[$field] = [string]$feature.$field }
+            }
+            $langFeatures[$featureId] = [PSCustomObject]$entry
+        }
+
+        $script:Lang = [PSCustomObject]@{
+            LanguageCode = 'en-US'
+            Chrome       = [PSCustomObject]@{}
+            Features     = [PSCustomObject]$langFeatures
+            UiGroups     = [PSCustomObject]@{}
+            Categories   = [PSCustomObject]@{}
+        }
+    }
 }
 
 Describe 'Get-RebootFeatureLabels' {
@@ -18,6 +41,7 @@ Describe 'Get-RebootFeatureLabels' {
             UndoFeature = [PSCustomObject]@{ RequiresReboot = $true; Label = 'Undoable feature'; UndoLabel = 'Undo feature' }
             NoRebootFeature = [PSCustomObject]@{ RequiresReboot = $false; Label = 'No reboot'; UndoLabel = 'Undo no reboot' }
         }
+        Sync-TestLangFeatures
     }
 
     It 'includes reboot-required selections once and uses undo labels for undo operations' {
@@ -43,6 +67,7 @@ Describe 'Get-RebootFeatureLabels' {
         $script:Params = @{}
         $script:UndoParams = @{ ApplyFeature = $true }
         $script:Features.ApplyFeature.UndoLabel = $null
+        Sync-TestLangFeatures
 
         $result = @(Get-RebootFeatureLabels)
 
@@ -57,6 +82,7 @@ Describe 'Get-RebootFeatureLabels' {
             RequiresReboot = $true
             Label = 'Feature without undo label'
         }
+        Sync-TestLangFeatures
 
         $result = @(Get-RebootFeatureLabels)
 
@@ -87,6 +113,7 @@ Describe 'Get-RebootFeatureLabels' {
             Label = 'Shared label'
             UndoLabel = 'Undo second shared label'
         }
+        Sync-TestLangFeatures
 
         $result = @(Get-RebootFeatureLabels)
 
@@ -110,6 +137,7 @@ Describe 'Get-RebootFeatureLabels' {
             Label = 'Numeric reboot'
             UndoLabel = 'Undo numeric reboot'
         }
+        Sync-TestLangFeatures
 
         $result = @(Get-RebootFeatureLabels)
 
@@ -130,6 +158,7 @@ Describe 'Get-RebootFeatureLabels' {
             Label = ' '
             UndoLabel = $null
         }
+        Sync-TestLangFeatures
 
         @(Get-RebootFeatureLabels).Count | Should -Be 0
     }

Tests/Import-ConfigToParams.Tests.ps1

@@ -1,10 +1,13 @@
 BeforeAll {
     . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Add-Parameter.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Import-ConfigToParams.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Test-ConfigConsistency.ps1')
     $script:ConfigFixturePath = Join-Path $PSScriptRoot 'TestData\JsonFileLoading\ExportedConfig.WithSettings.json'
     $script:SkipRegistryBackupFixturePath = Join-Path $PSScriptRoot 'TestData\JsonFileLoading\ExportedConfig.SkipRegistryBackup.json'
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Import-ConfigToParams' {

Tests/Import-JsonFile.Tests.ps1

@@ -42,4 +42,17 @@ Describe 'Import-JsonFile' {
         $result | Should -BeNullOrEmpty
         Should -Invoke Write-Error -Times 0 -Exactly
     }
+
+    It 'reads non-ASCII characters correctly from a UTF-8 file with no BOM, regardless of the system default encoding' {
+        # Unicode escapes here, not literal accented characters: this test file has no BOM, so
+        # PowerShell 5.1 would decode literal non-ASCII source characters using the system default
+        # codepage too, defeating the point of the assertion on a non-UTF-8-default machine.
+        $expectedName = "Espa$([char]0x00F1)ol"
+        $expectedNote = "caf$([char]0x00E9), na$([char]0x00EF)ve, $([char]0x00FC)ber"
+
+        $result = Import-JsonFile -filePath (Join-Path $script:FixturePath 'Config.Utf8NoBom.json')
+
+        $result.Name | Should -Be $expectedName
+        $result.Note | Should -Be $expectedNote
+    }
 }

Tests/Import-LanguageFile.Tests.ps1

@@ -0,0 +1,254 @@
+BeforeAll {
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot 'TestData\LanguageLoading'
+}
+
+Describe 'Resolve-LanguageFolder' {
+    It 'resolves <Case>' -ForEach @(
+        @{ Case = 'an exact match'; LanguageCode = 'en-US'; Expected = 'en-US' }
+        @{ Case = 'a second exact match'; LanguageCode = 'es-ES'; Expected = 'es-ES' }
+        @{ Case = 'a language-prefix match when no exact folder exists'; LanguageCode = 'es-AR'; Expected = 'es-ES' }
+        @{ Case = 'an unrelated locale to the en-US fallback'; LanguageCode = 'fr-FR'; Expected = 'en-US' }
+    ) {
+        Resolve-LanguageFolder -LanguageCode $LanguageCode | Should -Be $Expected
+    }
+}
+
+Describe 'Import-LanguageFile' {
+    It 'loads all three JSON files for the resolved language' {
+        $lang = Import-LanguageFile -LanguageCode 'en-US'
+
+        $lang.LanguageCode | Should -Be 'en-US'
+        $lang.Chrome.TitleBarClose | Should -Be 'Close'
+        $lang.Features.DisableTelemetry.Label | Should -Be 'Disable telemetry'
+        $lang.Categories.PrivacySuggestedContent.Label | Should -Be 'Privacy & Suggested Content'
+    }
+
+    It 'attaches an en-US Fallback when a non-en-US language is loaded' {
+        $lang = Import-LanguageFile -LanguageCode 'es-ES'
+
+        $lang.LanguageCode | Should -Be 'es-ES'
+        $lang.Fallback.LanguageCode | Should -Be 'en-US'
+    }
+
+    It 'does not attach a Fallback when en-US itself is loaded' {
+        $lang = Import-LanguageFile -LanguageCode 'en-US'
+
+        $lang.PSObject.Properties['Fallback'] | Should -BeNullOrEmpty
+    }
+
+    It 'falls back to en-US without warning when the requested language has no folder at all' {
+        # Resolve-LanguageFolder already resolves a nonexistent language straight to 'en-US',
+        # so there's no real fallback to warn about here, unlike the broken-folder case below.
+        Mock Write-Warning {}
+
+        $lang = Import-LanguageFile -LanguageCode 'fr-FR'
+
+        $lang.LanguageCode | Should -Be 'en-US'
+        Should -Invoke Write-Warning -Times 0 -Exactly
+    }
+
+    It 'warns and falls back to en-US when the requested language folder exists but fails to load' {
+        Mock Write-Warning {}
+        Mock Write-Error {}
+
+        $languagesPath = Join-Path $TestDrive 'WithWorkingFallback'
+        $brokenFolder = Join-Path $languagesPath 'xx-XX'
+        New-Item -ItemType Directory -Path $brokenFolder | Out-Null
+        'not valid json' | Out-File (Join-Path $brokenFolder 'Chrome.json')
+
+        $enUsFolder = Join-Path $languagesPath 'en-US'
+        Copy-Item -Path (Join-Path $PSScriptRoot 'TestData\LanguageLoading\en-US') -Destination $enUsFolder -Recurse
+
+        $lang = Import-LanguageFile -LanguageCode 'xx-XX' -LanguagesPath $languagesPath
+
+        $lang.LanguageCode | Should -Be 'en-US'
+        Should -Invoke Write-Warning -ParameterFilter { $Message -match "Failed to load language 'xx-XX'" } -Times 1 -Exactly
+        # The broken xx-XX folder is still expected to report load errors; the fallback en-US load itself must not.
+        Should -Invoke Write-Error -ParameterFilter { $Message -match 'Unable to load the en-US language files' } -Times 0
+    }
+
+    It 'returns null and reports an error when the requested language fails and en-US is unavailable too' {
+        Mock Write-Warning {}
+        Mock Write-Error {}
+
+        $languagesPath = Join-Path $TestDrive 'WithoutFallback'
+        $brokenFolder = Join-Path $languagesPath 'xx-XX'
+        New-Item -ItemType Directory -Path $brokenFolder | Out-Null
+        'not valid json' | Out-File (Join-Path $brokenFolder 'Chrome.json')
+
+        $lang = Import-LanguageFile -LanguageCode 'xx-XX' -LanguagesPath $languagesPath
+
+        $lang | Should -BeNullOrEmpty
+        Should -Invoke Write-Warning -ParameterFilter { $Message -match "Failed to load language 'xx-XX'" } -Times 1 -Exactly
+    }
+
+    It 'reports an error and returns null when en-US itself cannot be loaded' {
+        Mock Write-Error {}
+
+        $lang = Import-LanguageFile -LanguageCode 'en-US' -LanguagesPath $TestDrive
+
+        $lang | Should -BeNullOrEmpty
+        Should -Invoke Write-Error -ParameterFilter { $Message -match 'Unable to load the en-US language files' } -Times 1 -Exactly
+    }
+}
+
+Describe 'Get-PluralCategory' {
+    It 'returns <Expected> for a count of <Count>' -ForEach @(
+        @{ Count = 0; Expected = 'other' }
+        @{ Count = 1; Expected = 'one' }
+        @{ Count = 2; Expected = 'other' }
+        @{ Count = 5; Expected = 'other' }
+    ) {
+        Get-PluralCategory -LanguageCode 'en-US' -Count $Count | Should -Be $Expected
+    }
+}
+
+Describe 'Get-Translation' {
+    BeforeAll {
+        $script:EnLang = Import-LanguageFile -LanguageCode 'en-US'
+        $script:EsLang = Import-LanguageFile -LanguageCode 'es-ES'
+    }
+
+    It 'looks up a flat Chrome key' {
+        Get-Translation -Key 'TitleBarClose' -Lang $script:EnLang | Should -Be 'Close'
+    }
+
+    It 'looks up a Field on a Features entry' {
+        Get-Translation -Key 'DisableTelemetry' -Field 'Label' -Lang $script:EnLang | Should -Be 'Disable telemetry'
+        Get-Translation -Key 'DisableTelemetry' -Field 'ToolTip' -Lang $script:EnLang | Should -Be 'Disables telemetry collection.'
+    }
+
+    It 'looks up a Field on a Categories entry' {
+        Get-Translation -Key 'PrivacySuggestedContent' -Field 'Label' -Lang $script:EnLang | Should -Be 'Privacy & Suggested Content'
+    }
+
+    It 'looks up a Field on a UiGroups entry' {
+        Get-Translation -Key 'SearchIcon' -Field 'Label' -Lang $script:EnLang | Should -Be 'Taskbar search style'
+    }
+
+    It 'resolves the correct section for a key that exists as both a FeatureId and a GroupId' {
+        # ClearStart is a real collision in Config/Features.json: a FeatureId ("remove for this
+        # user only") and a GroupId (the combo heading above it) that share the same string.
+        # Mirrored in the TestData fixture above so this test doesn't depend on production content.
+        Get-Translation -Key 'ClearStart' -Field 'Label' -Section 'Features' -Lang $script:EnLang | Should -Be 'Remove for the selected user'
+        Get-Translation -Key 'ClearStart' -Field 'Label' -Section 'UiGroups' -Lang $script:EnLang | Should -Be 'Remove pinned apps from the start menu'
+        Get-Translation -Key 'ClearStart' -Field 'ToolTip' -Section 'UiGroups' -Lang $script:EnLang | Should -Be 'This setting allows you to quickly remove all pinned apps from the start menu.'
+    }
+
+    It 'returns the key itself when no language has it' {
+        Get-Translation -Key 'NoSuchKeyAnywhere' -Lang $script:EnLang | Should -Be 'NoSuchKeyAnywhere'
+    }
+
+    It 'returns the key itself when the field is missing on an entry that exists' {
+        Get-Translation -Key 'DisableTelemetry' -Field 'UndoLabel' -Lang $script:EnLang | Should -Be 'DisableTelemetry'
+    }
+
+    It 'falls back to en-US for a key missing from the active language' {
+        Get-Translation -Key 'TitleBarOptions' -Lang $script:EsLang | Should -Be 'Options'
+    }
+
+    It 'prefers the active language over the fallback when both have the key' {
+        Get-Translation -Key 'TitleBarClose' -Lang $script:EsLang | Should -Be 'Cerrar'
+    }
+
+    It 'resolves a plural-suffixed key by count, falling back to the bare key' {
+        Get-Translation -Key 'AppsSelectedCount' -Count 1 -Lang $script:EnLang | Should -Be '{0} app selected'
+        Get-Translation -Key 'AppsSelectedCount' -Count 5 -Lang $script:EnLang | Should -Be '{0} apps selected'
+    }
+
+    It 'substitutes FormatArgs into the resolved string' {
+        Get-Translation -Key 'AppsSelectedCount' -Count 1 -FormatArgs @(1) -Lang $script:EnLang | Should -Be '1 app selected'
+        Get-Translation -Key 'AppsSelectedCount' -Count 5 -FormatArgs @(5) -Lang $script:EnLang | Should -Be '5 apps selected'
+    }
+
+    It 'substitutes a zero FormatArgs value instead of treating the array as falsy' {
+        Get-Translation -Key 'AppsSelectedCount' -Count 0 -FormatArgs @(0) -Lang $script:EnLang | Should -Be '0 apps selected'
+    }
+
+    It 'returns the unformatted string instead of throwing when FormatArgs is empty' {
+        Get-Translation -Key 'AppsSelectedCount' -Count 1 -FormatArgs @() -Lang $script:EnLang | Should -Be '{0} app selected'
+    }
+
+    It 'warns and returns the unformatted string instead of throwing on a placeholder/argument count mismatch' {
+        Mock Write-Warning {}
+
+        $result = Get-Translation -Key 'TooManyPlaceholders' -FormatArgs @('only one arg') -Lang $script:EnLang
+
+        $result | Should -Be 'Value is {0} and {1}'
+        Should -Invoke Write-Warning -ParameterFilter { $Message -match 'TooManyPlaceholders' } -Times 1 -Exactly
+    }
+}
+
+Describe 'Test-LanguageKeyCoverage' {
+    It 'reports no missing or extra keys when a language is compared against itself' {
+        $coverage = Test-LanguageKeyCoverage -LanguageCode 'en-US'
+
+        $coverage.MissingKeys | Should -BeNullOrEmpty
+        $coverage.ExtraKeys | Should -BeNullOrEmpty
+    }
+
+    It 'flags every key missing from a partially translated language' {
+        $coverage = Test-LanguageKeyCoverage -LanguageCode 'es-ES'
+
+        $coverage.MissingKeys | Should -Contain 'TitleBarOptions'
+        $coverage.MissingKeys | Should -Contain 'AppsSelectedCount_one'
+        $coverage.MissingKeys | Should -Contain 'AppsSelectedCount_other'
+        $coverage.MissingKeys | Should -Contain 'Features.DisableTelemetry.Label'
+        $coverage.MissingKeys | Should -Contain 'Features.DisableTelemetry.ToolTip'
+        $coverage.MissingKeys | Should -Contain 'UiGroups.SearchIcon.Label'
+        $coverage.MissingKeys | Should -Contain 'Categories.PrivacySuggestedContent.Label'
+        $coverage.ExtraKeys | Should -BeNullOrEmpty
+    }
+
+    It 'does not flag a key the target language already has' {
+        $coverage = Test-LanguageKeyCoverage -LanguageCode 'es-ES'
+
+        $coverage.MissingKeys | Should -Not -Contain 'TitleBarClose'
+    }
+
+    It 'resolves a regional variant to its language-prefix match instead of erroring' {
+        $coverage = Test-LanguageKeyCoverage -LanguageCode 'es-AR'
+
+        $coverage.ResolvedLanguageCode | Should -Be 'es-ES'
+        $coverage.MissingKeys | Should -Contain 'TitleBarOptions'
+    }
+}
+
+Describe 'ConvertTo-LocalizedXaml' {
+    BeforeAll {
+        $script:EnLang = Import-LanguageFile -LanguageCode 'en-US'
+        $script:EsLang = Import-LanguageFile -LanguageCode 'es-ES'
+    }
+
+    It 'substitutes every marker and XML-escapes the resolved value' {
+        $xaml = '<Button Content="%LANG:TitleBarClose%"/>'
+
+        ConvertTo-LocalizedXaml -Xaml $xaml -Lang $script:EnLang | Should -Be '<Button Content="Close"/>'
+    }
+
+    It 'does not let one substituted value be re-matched by a later marker' {
+        $xaml = '<a Text="%LANG:TitleBarOptions%"/><b Text="%LANG:TitleBarClose%"/>'
+
+        ConvertTo-LocalizedXaml -Xaml $xaml -Lang $script:EnLang | Should -Be '<a Text="Options"/><b Text="Close"/>'
+    }
+
+    It 'throws when a marker key does not exist in any language' {
+        $xaml = '<Button Content="%LANG:NoSuchKeyAnywhere%"/>'
+
+        { ConvertTo-LocalizedXaml -Xaml $xaml -Lang $script:EnLang } | Should -Throw '*NoSuchKeyAnywhere*'
+    }
+
+    It 'falls back to en-US instead of throwing for a key missing from a partially translated language' {
+        $xaml = '<Button Content="%LANG:TitleBarOptions%"/>'
+
+        ConvertTo-LocalizedXaml -Xaml $xaml -Lang $script:EsLang | Should -Be '<Button Content="Options"/>'
+    }
+
+    It 'throws rather than stringifying a Features/UiGroups/Categories entry used by mistake' {
+        $xaml = '<TextBlock Text="%LANG:DisableTelemetry%"/>'
+
+        { ConvertTo-LocalizedXaml -Xaml $xaml -Lang $script:EnLang } | Should -Throw '*DisableTelemetry*'
+    }
+}

Tests/Invoke-Changes.Tests.ps1

@@ -20,7 +20,31 @@ BeforeAll {
     function Set-StoreSearchSuggestionsDisabledForAllUsers { $true }
     function Set-StoreSearchSuggestionsDisabled { param($StoreAppsDatabase) $true }
 
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Features\Invoke-Changes.ps1')
+
+    # Builds a $script:Lang fixture whose Features section mirrors $script:Features exactly,
+    # so Get-Translation resolves the same ApplyText/UndoLabel/ApplyUndoText text the fake
+    # FeatureIds in this file's fixtures expect, without duplicating per-test lookup data.
+    function Sync-TestLangFeatures {
+        $langFeatures = @{}
+        foreach ($featureId in $script:Features.Keys) {
+            $feature = $script:Features[$featureId]
+            $entry = @{}
+            foreach ($field in 'ApplyText', 'UndoLabel', 'ApplyUndoText') {
+                if ($null -ne $feature.$field) { $entry[$field] = [string]$feature.$field }
+            }
+            $langFeatures[$featureId] = [PSCustomObject]$entry
+        }
+
+        $script:Lang = [PSCustomObject]@{
+            LanguageCode = 'en-US'
+            Chrome       = [PSCustomObject]@{}
+            Features     = [PSCustomObject]$langFeatures
+            UiGroups     = [PSCustomObject]@{}
+            Categories   = [PSCustomObject]@{}
+        }
+    }
 }
 
 Describe 'Resolve-UndoRegFilePath' {
@@ -62,6 +86,7 @@ Describe 'Invoke-FeatureApply' {
             ReplaceStartAllUsers = [PSCustomObject]@{ ApplyText = 'Replace Start all users'; RegistryKey = '' }
             DisableStoreSearchSuggestions = [PSCustomObject]@{ ApplyText = 'Disable Store suggestions'; RegistryKey = '' }
         }
+        Sync-TestLangFeatures
         Mock Import-RegistryFile { $true }
         Mock Remove-SelectedApps { $true }
         Mock Invoke-ForceRemoveEdge { $true }
@@ -238,6 +263,7 @@ Describe 'Invoke-ApplyFeatures' {
             One = [PSCustomObject]@{ ApplyText = 'Apply one' }
             Two = [PSCustomObject]@{ ApplyText = 'Apply two' }
         }
+        Sync-TestLangFeatures
         $script:progressCalls = New-Object System.Collections.Generic.List[object]
         $script:ApplyProgressCallback = { param($Step, $Total, $Text) $script:progressCalls.Add(@($Step, $Total, $Text)) }
         Mock Invoke-FeatureApply { $true }
@@ -283,6 +309,7 @@ Describe 'Invoke-UndoFeatures' {
             RegistryUndo = [PSCustomObject]@{ UndoLabel = 'Undo registry'; ApplyUndoText = 'Restoring registry'; RegistryUndoKey = 'undo.reg' }
             CustomUndo = [PSCustomObject]@{ UndoLabel = 'Undo custom'; ApplyUndoText = ''; RegistryUndoKey = '' }
         }
+        Sync-TestLangFeatures
         Mock Resolve-UndoRegFilePath { param($FileName) "Undo\$FileName" }
         Mock Import-RegistryFile { $true }
         Mock Invoke-FeatureUndo { $true }

Tests/Invoke-SystemRestorePoint.Tests.ps1

@@ -4,7 +4,11 @@ BeforeAll {
     function Enable-ComputerRestore { param($Drive) }
     function Get-ComputerRestorePoint {}
     function Checkpoint-Computer { param($Description, $RestorePointType) }
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Features\Invoke-SystemRestorePoint.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Invoke-SystemRestorePoint' {

Tests/MainWindow-AppSelection.Tests.ps1

@@ -1,10 +1,14 @@
 BeforeAll {
     Add-Type -AssemblyName PresentationFramework
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\GUI\MainWindow-AppSelection.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\GUI\MainWindow-Deployment.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\GUI\MainWindow-Navigation.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\GUI\MainWindow-TweaksBuilder.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\GUI\Set-WindowThemeResources.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 
     function New-TestWindow {
         $window = New-Object System.Windows.Window

Tests/Registry-BackupFeatureValidation.Tests.ps1

@@ -1,8 +1,12 @@
 BeforeAll {
     function Get-RegistryBackupCapturePlans {}
 
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Registry-PathHelpers.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Features\Registry-BackupValidation.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Test-RegistryBackupMatchesSelectedFeatures' {

Tests/Registry-BackupValidation.Tests.ps1

@@ -2,8 +2,12 @@ BeforeAll {
     $registryPathHelperScriptPath = Join-Path $PSScriptRoot '..\Scripts\Helpers\Registry-PathHelpers.ps1'
     $validationScriptPath = Join-Path $PSScriptRoot '..\Scripts\Features\Registry-BackupValidation.ps1'
 
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . $registryPathHelperScriptPath
     . $validationScriptPath
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Get-NormalizedSelectedFeatureIdsFromBackup' {

Tests/Replace-StartMenu.Tests.ps1

@@ -1,7 +1,11 @@
 BeforeAll {
     function Get-UserDirectory { param($userName, $fileName, $exitIfPathNotFound) }
 
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Features\Replace-StartMenu.ps1')
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Get-StartMenuUserNameFromPath' {

Tests/Restore-BackupDialogFeatureLists.Tests.ps1

@@ -1,5 +1,6 @@
 BeforeAll {
     . (Join-Path $PSScriptRoot '..\Scripts\GUI\Restore-BackupDialogFeatureLists.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
 }
 
 Describe 'New-RestoreDialogState' {
@@ -9,6 +10,18 @@ Describe 'New-RestoreDialogState' {
             CustomFeature = [PSCustomObject]@{ Label = 'Custom feature'; Category = 'Privacy'; RegistryKey = '' }
             HiddenFeature = [PSCustomObject]@{ Label = 'Hidden feature'; Category = ''; RegistryKey = 'HiddenFeature.reg' }
         }
+
+        $script:Lang = [PSCustomObject]@{
+            LanguageCode = 'en-US'
+            Chrome       = [PSCustomObject]@{ RestoreUnknownFeature = 'Unknown feature' }
+            Features     = [PSCustomObject]@{
+                RegistryFeature = [PSCustomObject]@{ Label = 'Registry feature' }
+                CustomFeature   = [PSCustomObject]@{ Label = 'Custom feature' }
+                HiddenFeature   = [PSCustomObject]@{ Label = 'Hidden feature' }
+            }
+            UiGroups     = [PSCustomObject]@{}
+            Categories   = [PSCustomObject]@{}
+        }
     }
 
     It 'creates a dialog state with the supplied values' {

Tests/Restore-RegistryBackup.Tests.ps1

@@ -1,5 +1,7 @@
 BeforeAll {
     function Test-RunningAsSystem { $false }
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-JsonFile.ps1')
+    . (Join-Path $PSScriptRoot '..\Scripts\FileIO\Import-LanguageFile.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Registry-PathHelpers.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Get-FriendlyRegistryBackupTarget.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Helpers\Resolve-UserProfilePath.ps1')
@@ -8,6 +10,8 @@ BeforeAll {
     . (Join-Path $PSScriptRoot '..\Scripts\Features\Restore-RegistryApplyState.ps1')
     . (Join-Path $PSScriptRoot '..\Scripts\Features\Restore-RegistryBackup.ps1')
     $script:JsonFixturePath = Join-Path $PSScriptRoot 'TestData\JsonFileLoading'
+    $script:LanguagesPath = Join-Path $PSScriptRoot '..\Config\Languages'
+    $script:Lang = Import-LanguageFile -LanguageCode 'en-US'
 }
 
 Describe 'Import-RegistryBackup' {

Tests/TestData/JsonFileLoading/Config.Utf8NoBom.json

@@ -0,0 +1,4 @@
+{
+    "Name": "Español",
+    "Note": "café, naïve, über"
+}

Tests/TestData/LanguageLoading/en-US/Categories.json

@@ -0,0 +1,5 @@
+{
+  "PrivacySuggestedContent": {
+    "Label": "Privacy & Suggested Content"
+  }
+}

Tests/TestData/LanguageLoading/en-US/Chrome.json

@@ -0,0 +1,7 @@
+{
+  "TitleBarClose": "Close",
+  "TitleBarOptions": "Options",
+  "AppsSelectedCount_one": "{0} app selected",
+  "AppsSelectedCount_other": "{0} apps selected",
+  "TooManyPlaceholders": "Value is {0} and {1}"
+}

Tests/TestData/LanguageLoading/en-US/Features.json

@@ -0,0 +1,20 @@
+{
+  "Features": {
+    "DisableTelemetry": {
+      "Label": "Disable telemetry",
+      "ToolTip": "Disables telemetry collection."
+    },
+    "ClearStart": {
+      "Label": "Remove for the selected user"
+    }
+  },
+  "UiGroups": {
+    "SearchIcon": {
+      "Label": "Taskbar search style"
+    },
+    "ClearStart": {
+      "Label": "Remove pinned apps from the start menu",
+      "ToolTip": "This setting allows you to quickly remove all pinned apps from the start menu."
+    }
+  }
+}

Tests/TestData/LanguageLoading/es-ES/Categories.json

@@ -0,0 +1 @@
+{}

Tests/TestData/LanguageLoading/es-ES/Chrome.json

@@ -0,0 +1,3 @@
+{
+  "TitleBarClose": "Cerrar"
+}

Tests/TestData/LanguageLoading/es-ES/Features.json

@@ -0,0 +1,4 @@
+{
+  "Features": {},
+  "UiGroups": {}
+}

Tests/XamlContracts.Tests.ps1

@@ -54,9 +54,9 @@ Describe 'XAML UI contracts' {
         $applyWindow = Get-Content -LiteralPath (Join-Path $script:SchemaPath 'ApplyChangesWindow.xaml') -Raw
         $appWindow = Get-Content -LiteralPath (Join-Path $script:SchemaPath 'AppSelectionWindow.xaml') -Raw
 
-        $applyWindow | Should -Match 'AutomationProperties.Name="Cancel"'
-        $applyWindow | Should -Match 'AutomationProperties.Name="Close"'
-        $appWindow | Should -Match 'AutomationProperties.Name="Confirm"'
-        $appWindow | Should -Match 'AutomationProperties.Name="Cancel"'
+        $applyWindow | Should -Match 'AutomationProperties.Name="%LANG:ApplyCancelTooltip%"'
+        $applyWindow | Should -Match 'AutomationProperties.Name="%LANG:TitleBarClose%"'
+        $appWindow | Should -Match 'AutomationProperties.Name="%LANG:AppSelectionWindowConfirm%"'
+        $appWindow | Should -Match 'AutomationProperties.Name="%LANG:AppSelectionWindowCancel%"'
     }
 }