Migrate from .NET 6 to .NET 9 with IEBT Migrator

[Daymannovaes]

Summary

Migrates Mockaco from .NET 6.0 to .NET 9.0, including all dependencies and necessary code changes.

Changes Made

Framework Migration

• ✅ Updated all 3 projects to target net9.0:
  • Mockaco.AspNetCore (Library)
  • Mockaco (Console/Tool)
  • Mockaco.AspNetCore.Tests (Tests)
• ✅ Configured .NET 9.0.307 SDK via .tool-versions

Code Changes (Breaking Changes Fixed)

1. InvalidMockException.cs

   • Removed obsolete serialization constructor (SYSLIB0051)
   • Cleaned up unused using statements

2. ResponseMockingMiddleware.cs

   • Changed response.Headers.Add() to response.Headers.Append() (ASP0019)
   • Prevents ArgumentException on duplicate headers

NuGet Package Updates

Framework-Specific (Required)

• Microsoft.Extensions.FileProviders.Physical: 6.0.0 → 10.0.0
• GitVersion.MsBuild: 5.12.0 → 6.5.0

Critical Updates

• Microsoft.CodeAnalysis.CSharp.Scripting: 4.6.0 → 5.0.0 (Roslyn - core C# scripting feature)
• Serilog.AspNetCore: 7.0.0 → 9.0.0
• Serilog.Settings.Configuration: 7.0.0 → 9.0.0
• Serilog.Sinks.Console: 4.1.0 → 6.1.1
• Serilog.Sinks.File: 5.0.0 → 7.0.0

Test Infrastructure

• Microsoft.NET.Test.Sdk: 17.6.2 → 18.0.1
• xunit: 2.4.2 → 2.9.3
• xunit.runner.visualstudio: 2.4.5 → 3.1.5
• coverlet.collector: 6.0.0 → 6.0.4

Optional Packages

• Bogus: 34.0.2 → 35.6.5
• Newtonsoft.Json: 13.0.3 → 13.0.4
• Microsoft.OpenApi.Readers: 1.6.4 → 1.6.28
• FluentAssertions: 6.11.0 → 8.8.0
• Moq: 4.18.4 → 4.20.72
• Testcontainers: 3.2.0 → 4.8.1

Notes on System.CommandLine

• Kept at 2.0.0-beta1.21308.1 (not upgraded to GA 2.0.0)
• Reason: GA version has breaking API changes requiring significant refactoring
• Current beta version works perfectly with .NET 9

Test Results

✅ All 70 tests passing

• Runtime: 7.0 seconds
• No new test failures introduced
• 6 nullable reference warnings remain (pre-existing, non-critical)

Pending Work (Future PRs)

This PR focuses on the core migration. The following tasks are documented but not included:

• Update GitHub Actions workflow (.github/workflows/main-release.yml)
• Update Dockerfile to use .NET 9 base images
• Update README.md with .NET 9 requirements
• Address nullable reference warnings in test files

Testing Checklist

• All unit tests pass
• Build succeeds in Debug mode
• Build succeeds in Release mode
• Core Roslyn scripting functionality works (critical feature)
• Template transformation works
• Middleware pipeline works
• Docker build (pending Dockerfile update)
• CI/CD pipeline (pending GitHub Actions update)

Migration Documentation

See MIGRATION_PLAN.md for complete migration details, including:

• Detailed package update rationale
• Breaking change analysis
• Risk assessment
• Rollback procedures

References

• .NET 9 Release Notes
• .NET 9 Breaking Changes
• ASP.NET Core 9 Migration Guide

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