Write XAML Tests Skill

Creates XAML unit tests that verify XAML parsing, XamlC compilation, and source generation behavior.

When to Use

• ✅ Testing XAML parsing/inflation behavior

• ✅ Testing XamlC (IL generation) correctness

• ✅ Testing Source Generator output

• ✅ XAML-specific bugs (bindings, markup extensions, x:Name, etc.)

When NOT to Use

• ❌ Testing UI interactions or visual behavior → Use write-ui-tests skill

• ❌ Testing runtime behavior after page loads → Use write-ui-tests skill

• ❌ Testing platform-specific rendering → Use write-ui-tests skill

Required Input

Before invoking, ensure you have:

• Issue number (e.g., 12345)

• Issue description - what XAML behavior is broken

• Expected vs actual behavior

Workflow

Step 1: Read the XAML Unit Test Guidelines

cat .github/instructions/xaml-unittests.instructions.md

This contains the authoritative conventions for:

• File naming (MauiXXXXX.xaml and MauiXXXXX.xaml.cs )

• File location (src/Controls/tests/Xaml.UnitTests/Issues/ )

• Test patterns with [Values] XamlInflator

• XamlC testing with MockCompiler

• Source Generator testing with MockSourceGenerator

• Special file extensions for invalid codegen (.rt.xaml , .rtsg.xaml , .rtxc.xaml )

Step 2: Create Test Files

Following the conventions from Step 1, create:

• src/Controls/tests/Xaml.UnitTests/Issues/MauiXXXXX.xaml

• src/Controls/tests/Xaml.UnitTests/Issues/MauiXXXXX.xaml.cs

Step 3: Verify Tests Compile and Run

Build the test project

dotnet build src/Controls/tests/Xaml.UnitTests/Controls.Xaml.UnitTests.csproj -c Debug --no-restore -v q

Run specific test

dotnet test src/Controls/tests/Xaml.UnitTests/Controls.Xaml.UnitTests.csproj --filter "FullyQualifiedName~MauiXXXXX" --no-build

Step 4: Verify Test Behavior

• For bug reproduction tests: Tests should FAIL before fix, PASS after fix

• For regression tests: Tests should PASS to confirm behavior works

Output

After completion, report:

✅ XAML unit test created for Issue #XXXXX

Files:

• src/Controls/tests/Xaml.UnitTests/Issues/MauiXXXXX.xaml
• src/Controls/tests/Xaml.UnitTests/Issues/MauiXXXXX.xaml.cs

Test method: DescriptiveTestName Inflators tested: Runtime, XamlC, SourceGen Verification: Tests [PASS/FAIL] as expected

References

• Full conventions: .github/instructions/xaml-unittests.instructions.md

• Test project: src/Controls/tests/Xaml.UnitTests/

• Existing issue tests: src/Controls/tests/Xaml.UnitTests/Issues/