Add AGENTS.md with comprehensive build and test documentation (#1627)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: Bart Koelman <[email protected]>

Author: Copilot

AGENTS.md

@@ -0,0 +1,75 @@
+# Steeltoe Build and Test Guide for Developers and CI/CD Agents
+
+This document provides essential guidelines for working with the Steeltoe codebase. For detailed build and test procedures, refer to the [GitHub workflows](.github/workflows/) which serve as the source of truth.
+
+## General Guidelines
+
+### Code Review and Suggestions
+- Only make high confidence suggestions when reviewing code changes.
+- Always use the latest stable version of C#.
+- Never add or change `global.json` unless explicitly asked to.
+- Never change `NuGet.config` files unless explicitly asked to.
+
+### Null Handling
+- Declare variables non-nullable, and check for null at public API entry points.
+- For internal code, trust the C# null annotations and don't add null checks when the type system says a value cannot be null.
+
+### Writing Tests
+- Do not emit "Act", "Arrange" or "Assert" comments in test code.
+- Tests should pass before committing and pushing changes.
+- When possible, code coverage levels should be increased or at least maintained.
+
+## Prerequisites
+
+- **.NET SDK 10.0** (latest patch version)
+- **.NET Runtime 8.0** (latest patch version)
+- **.NET Runtime 9.0** (latest patch version)
+
+Verify your installation:
+```bash
+dotnet --list-sdks
+dotnet --list-runtimes
+```
+
+## Quick Start
+
+For quick iteration during development:
+```bash
+dotnet build
+dotnet test
+```
+
+For final validation before committing changes:
+```bash
+dotnet build src/Steeltoe.All.sln --configuration Release
+dotnet test src/Steeltoe.All.sln --configuration Release
+```
+
+### Run Tests
+
+For detailed test procedures including environment-specific filters, test categories, and coverage collection, see [`.github/workflows/Steeltoe.All.yml`](.github/workflows/Steeltoe.All.yml).
+
+**Important context for agents:**
+- Tests run on multiple frameworks: net8.0, net9.0, and net10.0
+- Tests use xUnit trait categories: `Integration` (requires Docker services), `MemoryDumps` (generates memory dumps)
+- Platform-specific test skipping uses attributes like `[FactSkippedOnPlatform]` and `[TheorySkippedOnPlatform]` instead of trait categories
+- Integration tests require Docker containers to be running (e.g., Config Server, Eureka Server) and are primarily designed for Linux CI environments
+- When writing tests, use `[Trait("Category", "Integration")]` for tests requiring external services like Docker containers
+
+## Code Style Validation
+
+Steeltoe uses ReSharper/Rider code cleanup tools via `regitlint` to enforce consistent code style. The CI workflow (`.github/workflows/verify-code-style.yml`) automatically verifies code style on all pull requests.
+
+To run code cleanup locally:
+```powershell
+./cleanupcode.ps1 main
+```
+
+If your PR fails the code style check, run `cleanupcode.ps1` locally and commit the changes.
+
+## Additional Resources
+
+- [Steeltoe Documentation](https://steeltoe.io/)
+- [Contributing Guidelines](https://github.com/SteeltoeOSS/Steeltoe/wiki)
+- [CI Workflow](.github/workflows/Steeltoe.All.yml)
+- [Code Style Workflow](.github/workflows/verify-code-style.yml)

src/Management/test/Endpoint.Test/ManagementOptionsTest.cs

@@ -20,7 +20,7 @@ namespace Steeltoe.Management.Endpoint.Test;
 
 public sealed class ManagementOptionsTest
 {
-    private static readonly JsonSerializerOptions DefaultJsonSerializerOptions = new JsonSerializerOptions
+    private static readonly JsonSerializerOptions ExpectedJsonSerializerOptions = new JsonSerializerOptions
     {
         PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
         Converters =
@@ -51,7 +51,7 @@ public async Task Configures_default_settings()
         options.Port.Should().Be(0);
         options.SslEnabled.Should().BeFalse();
         options.UseStatusCodeFromResponse.Should().BeTrue();
-        options.SerializerOptions.Should().BeEquivalentTo(DefaultJsonSerializerOptions);
+        options.SerializerOptions.Should().BeEquivalentTo(ExpectedJsonSerializerOptions);
         options.CustomJsonConverters.Should().BeEmpty();
 
         options.GetBasePath("/cloudfoundryapplication/info").Should().Be("/cloudfoundryapplication");
@@ -97,7 +97,7 @@ public async Task Configures_custom_settings()
         options.SslEnabled.Should().BeTrue();
         options.UseStatusCodeFromResponse.Should().BeFalse();
 
-        options.SerializerOptions.Should().BeEquivalentTo(new JsonSerializerOptions(DefaultJsonSerializerOptions)
+        options.SerializerOptions.Should().BeEquivalentTo(new JsonSerializerOptions(ExpectedJsonSerializerOptions)
         {
             WriteIndented = true,
             Converters =