--- name: jit-regression-test description: Extract a standalone JIT regression test case from a given GitHub issue and save it under the JitBlue folder. Use this when asked to create or extract a JIT regression test from an issue. --- # JIT Regression Test Extraction When you need to extract a JIT regression test case from a GitHub issue, follow this process to create a properly structured test under `src\/tests\/JIT\/Regression\/JitBlue\/`. ## Step 1: Gather Information from the GitHub Issue From the GitHub issue, extract: 1. **Issue number** - Used to name the test folder and files (e.g., issue #99391 → `Runtime_99391`) 2. **Reproduction code** - The C# code that demonstrates the bug. If no code provided, try to compose it yourself. 3. **Environment variables** - Any DOTNET_* environment variables required to reproduce the bug 4. **Expected behavior** - What the correct output\/behavior should be ## Step 2: Create the Test Directory Create a new folder under `src\/tests\/JIT\/Regression\/JitBlue\/`: ``` src\/tests\/JIT\/Regression\/JitBlue\/Runtime_\/ ``` ## Step 3: Create the Test File Create a `Runtime_.cs` file following these conventions: Example: ```csharp \/\/ Licensed to the .NET Foundation under one or more agreements. \/\/ The .NET Foundation licenses this file to you under the MIT license. using System; using System.Runtime.CompilerServices; using Xunit; public class Runtime_ { [Fact] public static void TestEntryPoint() { \/\/ Test code that exercises the bug \/\/ Use Assert.Equal, Assert.True, etc. for validation } } ``` ### Key Conventions - **License header**: Always include the standard .NET Foundation license header - **Class name**: Match the file name exactly (`Runtime_`) - **Test method**: Use `[Fact]` attribute and name the method `TestEntryPoint()` or `Test()` - **Assertions**: Use Xunit's helpers or just throw plain exceptions. ### Example: Simple Test (from Runtime_99391) ```csharp \/\/ Licensed to the .NET Foundation under one or more agreements. \/\/ The .NET Foundation licenses this file to you under the MIT license. namespace Runtime_99391; using System; using System.Runtime.CompilerServices; using System.Numerics; using Xunit; public class Runtime_99391 { [Fact] public static void TestEntryPoint() { Vector2 result2a = Vector2.Normalize(Value2); Assert.Equal(new Vector2(0, 1), result2a); } private static Vector2 Value2 { [MethodImpl(MethodImplOptions.NoInlining)] get => new Vector2(0, 2); } } ``` ## [Optional] Step 4: Create a .csproj File (Only When Needed) A custom `.csproj` file is **only required** when: - Environment variables are needed to reproduce the bug (such as `DOTNET_JitStressModeNames`) - Special compilation settings are required It should be located next to the test source file with the following name: `Runtime_.csproj`. Example: ```xml True<\/Optimize> None<\/DebugType> true<\/RequiresProcessIsolation> <\/PropertyGroup> <\/ItemGroup> <\/Project> ``` ## Important Notes - **No .csproj needed for simple tests**: Most tests only need the `.cs` file. The test infrastructure uses default settings that work for most cases. - **Look at recent tests**: When in doubt, examine recent tests under `src\/tests\/JIT\/Regression\/JitBlue\/Runtime_*` for the latest conventions. - **Use `[MethodImpl(MethodImplOptions.NoInlining)]`**: When you need to prevent inlining to reproduce a JIT bug. - **Minimize the reproduction**: Strip down the test code to the minimal case that reproduces the issue.