Modernize .editorconfig and enforce IDE0003 in CI

.editorconfig

@@ -1,10 +1,149 @@
-## IDE-independent coding style via EditorConfig: https://editorconfig.org/
-
+# top-most EditorConfig file
 root = true
 
+###############################################################################
+# Universal defaults (all files)
+###############################################################################
 [*]
+charset = utf-8
 indent_style = space
 indent_size = 4
-charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
+
+###############################################################################
+# XML / MSBuild project & config files
+###############################################################################
+[*.{xml,props,targets,csproj,vcxproj,vcxproj.filters,appxmanifest,manifest,resw,resx,config,nuspec,vsixmanifest,slnx}]
+indent_size = 2
+
+###############################################################################
+# JSON / YAML config files
+###############################################################################
+[*.{json,json5,yml,yaml}]
+indent_size = 2
+
+###############################################################################
+# Markdown (preserve trailing whitespace for hard line breaks)
+###############################################################################
+[*.md]
+trim_trailing_whitespace = false
+
+###############################################################################
+# C# style and analyzer policy
+###############################################################################
+[*.cs]
+csharp_using_directive_placement = outside_namespace:silent
+csharp_prefer_simple_using_statement = true:suggestion
+csharp_prefer_braces = true:silent
+csharp_style_namespace_declarations = block_scoped:silent
+csharp_style_prefer_method_group_conversion = true:silent
+csharp_style_expression_bodied_methods = false:silent
+csharp_style_expression_bodied_constructors = false:silent
+csharp_style_expression_bodied_operators = false:silent
+csharp_style_expression_bodied_properties = true:silent
+csharp_style_expression_bodied_indexers = true:silent
+csharp_style_expression_bodied_accessors = true:silent
+csharp_style_expression_bodied_lambdas = true:silent
+csharp_style_expression_bodied_local_functions = false:silent
+csharp_indent_labels = one_less_than_current
+csharp_style_throw_expression = true:suggestion
+csharp_style_prefer_null_check_over_type_check = true:suggestion
+csharp_prefer_simple_default_expression = true:suggestion
+csharp_style_prefer_local_over_anonymous_function = true:suggestion
+csharp_style_prefer_index_operator = true:suggestion
+csharp_style_prefer_range_operator = true:suggestion
+csharp_style_implicit_object_creation_when_type_is_apparent = true:suggestion
+csharp_style_prefer_tuple_swap = true:suggestion
+csharp_style_inlined_variable_declaration = true:suggestion
+csharp_style_prefer_top_level_statements = true:silent
+
+# 'this.' qualification: prefer no qualifier (IDE0003). Promoted to warning and
+# enforced in CI via build\scripts\VerifyCodeStyle.ps1 (dotnet format), since
+# csc does not reliably surface IDE-prefixed analyzers at build time.
+dotnet_style_qualification_for_field = false:warning
+dotnet_style_qualification_for_property = false:warning
+dotnet_style_qualification_for_method = false:warning
+dotnet_style_qualification_for_event = false:warning
+dotnet_diagnostic.IDE0003.severity = warning
+
+###############################################################################
+# .NET naming & code-style (C# and VB)
+###############################################################################
+[*.{cs,vb}]
+#### Naming styles ####
+
+# Naming rules
+
+dotnet_naming_rule.interface_should_be_begins_with_i.severity = suggestion
+dotnet_naming_rule.interface_should_be_begins_with_i.symbols = interface
+dotnet_naming_rule.interface_should_be_begins_with_i.style = begins_with_i
+
+dotnet_naming_rule.types_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.types_should_be_pascal_case.symbols = types
+dotnet_naming_rule.types_should_be_pascal_case.style = pascal_case
+
+dotnet_naming_rule.non_field_members_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.non_field_members_should_be_pascal_case.symbols = non_field_members
+dotnet_naming_rule.non_field_members_should_be_pascal_case.style = pascal_case
+
+# Symbol specifications
+
+dotnet_naming_symbols.interface.applicable_kinds = interface
+dotnet_naming_symbols.interface.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.interface.required_modifiers =
+
+dotnet_naming_symbols.types.applicable_kinds = class, struct, interface, enum
+dotnet_naming_symbols.types.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.types.required_modifiers =
+
+dotnet_naming_symbols.non_field_members.applicable_kinds = property, event, method
+dotnet_naming_symbols.non_field_members.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.non_field_members.required_modifiers =
+
+# Naming styles
+
+dotnet_naming_style.begins_with_i.required_prefix = I
+dotnet_naming_style.begins_with_i.required_suffix =
+dotnet_naming_style.begins_with_i.word_separator =
+dotnet_naming_style.begins_with_i.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix =
+dotnet_naming_style.pascal_case.required_suffix =
+dotnet_naming_style.pascal_case.word_separator =
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+
+#### .NET code-style preferences ####
+
+dotnet_style_coalesce_expression = true:suggestion
+dotnet_style_null_propagation = true:suggestion
+dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggestion
+dotnet_style_prefer_auto_properties = true:silent
+dotnet_style_object_initializer = true:suggestion
+dotnet_style_collection_initializer = true:suggestion
+dotnet_style_prefer_simplified_boolean_expressions = true:suggestion
+dotnet_style_prefer_conditional_expression_over_assignment = true:silent
+dotnet_style_prefer_conditional_expression_over_return = true:silent
+dotnet_style_explicit_tuple_names = true:suggestion
+dotnet_style_operator_placement_when_wrapping = beginning_of_line
+dotnet_style_prefer_inferred_tuple_names = true:suggestion
+dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
+dotnet_style_prefer_compound_assignment = true:suggestion
+dotnet_style_prefer_simplified_interpolation = true:suggestion
+dotnet_style_namespace_match_folder = true:suggestion
+tab_width = 4
+indent_size = 4
+
+###############################################################################
+# C++ - Visual C++ Include Cleanup settings
+###############################################################################
+[*.{c++,cc,cpp,cppm,cxx,h,h++,hh,hpp,hxx,inl,ipp,ixx,tlh,tli}]
+
+cpp_include_cleanup_add_missing_error_tag_type = suggestion
+cpp_include_cleanup_remove_unused_error_tag_type = dimmed
+cpp_include_cleanup_sort_after_edits = true
+cpp_sort_includes_error_tag_type = warning
+cpp_sort_includes_priority_case_sensitive = false
+cpp_sort_includes_priority_style = angle_brackets
+cpp_includes_style = default
+cpp_includes_use_forward_slash = true

.github/workflows/action-ci.yml

@@ -7,6 +7,19 @@ on:
     branches: [main, release/**, feature/**]
   workflow_dispatch:
 jobs:
+  verifyCodeStyle:
+    name: Verify code style (IDE0003)
+    runs-on: windows-2025-vs2026
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-dotnet@v4
+      name: Setup .NET SDK
+      with:
+        dotnet-version: '10.0.x'
+    - run: ./build/scripts/VerifyCodeStyle.ps1
+      shell: pwsh
+      name: Verify no unnecessary this. (IDE0003)
+
   defineBuilds:
     name: Define builds
     runs-on: windows-2025-vs2026

build/scripts/VerifyCodeStyle.ps1

@@ -0,0 +1,115 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+<#
+.SYNOPSIS
+    Verifies that the C# source is free of unnecessary 'this.' qualifications
+    (IDE0003), enforcing the '.editorconfig' single-source-of-truth policy.
+
+.DESCRIPTION
+    The Roslyn IDE-prefixed analyzers (IDE0003 et al.) ship with the .NET SDK
+    but are not reliably surfaced by csc.exe at build time. The 'dotnet format
+    style' host runs the same Roslyn analyzer and honors the '.editorconfig'
+    severity ('dotnet_diagnostic.IDE0003.severity = warning'), so this script
+    uses it as the build-time enforcement gate.
+
+    'dotnet format' uses the SDK MSBuild workspace loader, which cannot load
+    old-style UWP projects (the main Calculator app and its managed view
+    models) or the native C++ test projects. Only SDK-style C# projects are
+    listed in the allowlist below; all projects share the same '.editorconfig'
+    rules. The allowlist is a positive list, so new projects are
+    safe-by-default until explicitly added.
+
+    Restore is performed explicitly per project (and its exit code checked)
+    before formatting: the allowlisted projects carry PackageReference
+    dependencies that must be restored to load in the workspace, and a restore
+    failure should fail the gate loudly rather than letting 'dotnet format'
+    proceed against a partially loaded workspace.
+
+.PARAMETER Diagnostics
+    Comma-separated diagnostic IDs to enforce. Defaults to 'IDE0003'.
+
+.EXAMPLE
+    .\build\scripts\VerifyCodeStyle.ps1
+    Verifies the allowlisted SDK-style C# projects against IDE0003.
+
+.EXAMPLE
+    .\build\scripts\VerifyCodeStyle.ps1 -Diagnostics 'IDE0003,IDE0005'
+    Also enforces IDE0005 (remove unnecessary usings).
+#>
+[CmdletBinding()]
+param(
+    [string] $Diagnostics = 'IDE0003'
+)
+
+$ErrorActionPreference = 'Stop'
+
+# Resolve the repo root (this script lives in <root>\build\scripts).
+$root = if ($env:BUILD_SOURCESDIRECTORY) { $env:BUILD_SOURCESDIRECTORY } else { (Resolve-Path (Join-Path $PSScriptRoot '..\..')).Path }
+
+# SDK-style C# projects that 'dotnet format' can load. The old-style UWP
+# projects (Calculator, Calculator.ManagedViewModels) and the native C++ test
+# projects (CalculatorUnitTests) are excluded because the dotnet CLI workspace
+# loader cannot evaluate them.
+$sdkProjects = @(
+    'src\CalculatorUITestFramework\CalculatorUITestFramework.csproj',
+    'src\CalculatorUITests\CalculatorUITests.csproj'
+)
+
+Write-Host "Verifying code style for diagnostics: $Diagnostics"
+Write-Host "Tooling: dotnet $(dotnet --version)"
+Write-Host "Repo root: $root"
+Write-Host ""
+Write-Host "SDK-style projects to check:"
+$sdkProjects | ForEach-Object { Write-Host "  $_" }
+Write-Host ""
+
+$failed = $false
+
+foreach ($relPath in $sdkProjects)
+{
+    $projPath = Join-Path $root $relPath
+
+    if (-not (Test-Path $projPath))
+    {
+        Write-Host "##[error]Allowlisted project not found: $relPath"
+        $failed = $true
+        continue
+    }
+
+    Write-Host "Checking: $relPath"
+
+    # Restore explicitly first so a restore/feed failure fails the gate loudly,
+    # rather than letting 'dotnet format' run against a partially loaded
+    # workspace and report success without analyzing anything.
+    & dotnet restore $projPath
+
+    if ($LASTEXITCODE -ne 0)
+    {
+        Write-Host "##[error]Restore failed for: $relPath"
+        $failed = $true
+        continue
+    }
+
+    & dotnet format style $projPath `
+        --no-restore `
+        --verify-no-changes `
+        --severity warn `
+        --diagnostics $Diagnostics
+
+    if ($LASTEXITCODE -ne 0)
+    {
+        Write-Host "##[error]Code style violation ($Diagnostics) in: $relPath"
+        $failed = $true
+    }
+}
+
+if ($failed)
+{
+    Write-Host ''
+    Write-Host "##[error]Code style violations detected ($Diagnostics)."
+    Write-Host '##[error]Run the following locally to fix:'
+    Write-Host "##[error]  dotnet format style <project.csproj> --severity warn --diagnostics $Diagnostics"
+    exit 1
+}
+
+Write-Host ''
+Write-Host "##[section]Code style verification passed (no $Diagnostics violations)."

src/CalculatorUITestFramework/CalculatorDriver.cs

@@ -38,10 +38,10 @@ private CalculatorDriver()
 
         public void SetupCalculatorSession(TestContext context)
         {
-            this.server = new WinAppDriverLocalServer();
+            server = new WinAppDriverLocalServer();
 
             // Launch Calculator application if it is not yet launched
-            if (this.CalculatorSession == null)
+            if (CalculatorSession == null)
             {
                 // Create a new  WinAppDriver session to bring up an instance of the Calculator application
                 // Note: Multiple calculator windows (instances) share the same process Id
@@ -57,25 +57,25 @@ public void SetupCalculatorSession(TestContext context)
                 }
 
                 options.AddAdditionalCapability("deviceName", "WindowsPC");
-                this.CalculatorSession = new WindowsDriver<WindowsElement>(this.server.ServiceUrl, options);
-                this.CalculatorSession.Manage().Timeouts().ImplicitWait = TimeSpan.FromSeconds(10);
-                Assert.IsNotNull(this.CalculatorSession);
+                CalculatorSession = new WindowsDriver<WindowsElement>(server.ServiceUrl, options);
+                CalculatorSession.Manage().Timeouts().ImplicitWait = TimeSpan.FromSeconds(10);
+                Assert.IsNotNull(CalculatorSession);
             }
         }
 
         public void TearDownCalculatorSession()
         {
             // Close the application and delete the session
-            if (this.CalculatorSession != null)
+            if (CalculatorSession != null)
             {
-                this.CalculatorSession.Quit();
-                this.CalculatorSession = null;
+                CalculatorSession.Quit();
+                CalculatorSession = null;
             }
 
-            if (this.server != null)
+            if (server != null)
             {
-                this.server.Dispose();
-                this.server = null;
+                server.Dispose();
+                server = null;
             }
         }
     }

src/CalculatorUITestFramework/CalculatorResults.cs

@@ -11,17 +11,17 @@ namespace CalculatorUITestFramework
     public class CalculatorResults
     {
         private WindowsDriver<WindowsElement> session => CalculatorDriver.Instance.CalculatorSession;
-        private WindowsElement CalculatorAlwaysOnTopResults => this.session.TryFindElementByAccessibilityId("CalculatorAlwaysOnTopResults");
-        private WindowsElement CalculatorResult => this.session.TryFindElementByAccessibilityId("CalculatorResults");
-        private WindowsElement CalculatorExpression => this.session.TryFindElementByAccessibilityId("CalculatorExpression");
+        private WindowsElement CalculatorAlwaysOnTopResults => session.TryFindElementByAccessibilityId("CalculatorAlwaysOnTopResults");
+        private WindowsElement CalculatorResult => session.TryFindElementByAccessibilityId("CalculatorResults");
+        private WindowsElement CalculatorExpression => session.TryFindElementByAccessibilityId("CalculatorExpression");
 
         /// <summary>
         /// Gets the text from the display control in AoT mode and removes the narrator text that is not displayed in the UI.
         /// </summary>
         /// <returns>The string shown in the UI.</returns>
         public string GetAoTCalculatorResultText()
         {
-            return this.CalculatorAlwaysOnTopResults.Text.Replace("Display is", string.Empty).Trim();
+            return CalculatorAlwaysOnTopResults.Text.Replace("Display is", string.Empty).Trim();
         }
 
         /// <summary>
@@ -30,7 +30,7 @@ public string GetAoTCalculatorResultText()
         /// <returns>The string shown in the UI.</returns>
         public string GetCalculatorResultText()
         {
-            return this.CalculatorResult.Text.Replace("Display is", string.Empty).Trim();
+            return CalculatorResult.Text.Replace("Display is", string.Empty).Trim();
         }
 
         /// <summary>
@@ -39,7 +39,7 @@ public string GetCalculatorResultText()
         /// <returns>The string shown in the UI.</returns>
         public string GetCalculatorExpressionText()
         {
-            return this.CalculatorExpression.Text.Replace("Expression is", string.Empty).Trim();
+            return CalculatorExpression.Text.Replace("Expression is", string.Empty).Trim();
         }
 
         /// <summary>
@@ -48,7 +48,7 @@ public string GetCalculatorExpressionText()
         /// <returns>The string shown in the UI.</returns>
         public void IsResultsDisplayPresent()
         {
-            Assert.IsNotNull(this.CalculatorResult);
+            Assert.IsNotNull(CalculatorResult);
         }
 
         /// <summary>