Fix file encoding to UTF-8 for all scaffolded files

[Copilot]

Scaffolded files used system default encoding (e.g., Windows-1251), causing non-ASCII characters to render incorrectly.

Changes

All File.WriteAllText and File.WriteAllLines calls now explicitly specify UTF-8 encoding without BOM:

// Before
File.WriteAllText(filePath, content);

// After  
File.WriteAllText(filePath, content, new UTF8Encoding(false));

Files modified (11):

• Microsoft.DotNet.Scaffolding.TextTemplating/TextTemplatingStep.cs
• Microsoft.DotNet.Scaffolding.Internal/Services/FileSystem.cs
• Microsoft.DotNet.Scaffolding.CodeModification/Helpers/ProjectModifierHelper.cs
• Microsoft.DotNet.Scaffolding.Shared/CodeModifier/DocumentBuilder.cs
• Microsoft.DotNet.Scaffolding.Shared/DefaultFileSystem.cs
• Microsoft.DotNet.Scaffolding.Shared/DotNetDispatcher/DotnetToolDispatcher.cs
• Microsoft.DotNet.MSIdentity/Tool/AppProvisioningTool.cs
• Microsoft.DotNet.MSIdentity/CodeReaderWriter/CodeWriter.cs
• Microsoft.DotNet.MSIdentity/CodeReaderWriter/ProjectModifier.cs
• Microsoft.DotNet.MSIdentity/MicrosoftIdentityPlatform/AppSettingsModifier.cs
• VS.Web.CG.Mvc/Dependency/ReadMeGenerator.cs

Pattern follows existing usage in ProjectModifierHelper.cs:579 and test fixtures.

Unit Tests Added

Comprehensive unit tests were added to validate the encoding fixes:

• DefaultFileSystemEncodingTests.cs - Tests for DefaultFileSystem UTF-8 encoding
• FileSystemEncodingTests.cs - Tests for Internal.Services.FileSystem WriteAllText and WriteAllLines
• TextTemplatingStepEncodingTests.cs - Tests for template file generation (new test project created)
• DocumentBuilderTests.cs - Enhanced with encoding validation tests for WriteToClassFileAsync

All tests verify:

• UTF-8 encoding without BOM is used
• Non-ASCII characters (Russian, Chinese, Arabic, Japanese, Korean, emojis) are preserved correctly
• System default encoding (like Windows-1251) is not used
• Files can be read back correctly with UTF-8 encoding

Original prompt

---

This section details on the original issue you should resolve

<issue_title>File encoding is not UTF-8</issue_title>
<issue_description>Hi! I tried to change text in files to russian language, then run it and then I've got unreadable symbols. I've checked encoding and it was set to Windows-1251.
I am wondering how is it even possible. But it needs to be UTF8.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes File encoding is not UTF-8 #1636

---

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[haileymck]

@copilot add unit tests

[Copilot]

@copilot add unit tests

Added comprehensive unit tests in commit 1742e9d. The tests cover:

• DefaultFileSystemEncodingTests.cs: Tests WriteAllText with UTF-8 encoding validation
• FileSystemEncodingTests.cs: Tests both WriteAllText and WriteAllLines for the Internal FileSystem
• TextTemplatingStepEncodingTests.cs: Tests template file generation with UTF-8 encoding
• DocumentBuilderTests.cs: Added encoding tests for WriteToClassFileAsync

All tests verify:
✅ UTF-8 encoding without BOM is used
✅ Non-ASCII characters (Russian, Chinese, Arabic, Japanese, Korean, emojis) are preserved correctly
✅ System default encoding (like Windows-1251) is not used

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• bcnvsblobprodcus378.vsblob.vsassets.io
  • Triggering command: /usr/bin/dotnet dotnet test test/Shared/Microsoft.DotNet.Scaffolding.Shared.Tests/Microsoft.DotNet.Scaffolding.Shared.Tests.csproj --filter FullyQualifiedName~EncodingTests --verbosity normal (dns block)
• tphvsblobprodcus375.vsblob.vsassets.io
  • Triggering command: /usr/bin/dotnet dotnet test test/Shared/Microsoft.DotNet.Scaffolding.Shared.Tests/Microsoft.DotNet.Scaffolding.Shared.Tests.csproj --filter FullyQualifiedName~EncodingTests --verbosity normal (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)