Write Tests Agent

The Write Tests Agent is a specialized AI assistant that determines what type of tests are needed and invokes the appropriate skill.

How to Use This Agent

• VS Code: Custom Agents in VS Code
• Copilot CLI: GitHub Copilot CLI

See Export Your Chat Sessions after completing your work.

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When to Use

YES, use this agent if:

• User says "write tests for issue #XXXXX"
• User says "add test coverage for..."
• User says "create automated tests for..."
• PR needs tests added

NO, use different agent if:

• "Test this PR manually" → use sandbox-agent
• "Review this PR" → use pr agent
• "Fix issue #XXXXX" (no PR exists) → suggest /delegate command

Test Type Determination

The agent analyzes the issue/request to determine what type of tests are needed:

Scenario	Test Type	Skill Used
UI behavior, visual bugs, user interactions	UI Tests	write-ui-tests
XAML parsing, compilation, source generation	XAML Tests	write-xaml-tests
API behavior, logic, calculations	Unit Tests	(future)
Integration, end-to-end	Integration Tests	(future)

Currently supported: UI Tests and XAML Tests.

Example Prompts

For UI Tests

write UI test for issue #12345

write UI test for CollectionView item selection

create UI test that verifies Button click updates a Label

write UI test for Android SafeArea issue #12345

For XAML Tests

write XAML test for issue #12345 which is about binding compilation

create XAML test for x:Name resolution

write test for XamlC behavior on markup extensions

What Happens

For UI Tests

The agent invokes the write-ui-tests skill which:

1. Reads the UI test guidelines
2. Creates HostApp page in TestCases.HostApp/Issues/
3. Creates NUnit test in TestCases.Shared.Tests/Tests/Issues/
4. Verifies tests FAIL (proves they catch the bug)

For XAML Tests

The agent invokes the write-xaml-tests skill which:

1. Reads the XAML unit test guidelines
2. Creates XAML and code-behind files in Xaml.UnitTests/Issues/
3. Builds and runs the test

🛑 Critical Requirement (UI Tests)

Tests must FAIL before the skill reports success. A passing test does NOT prove it catches the bug.

If tests keep passing after 3 iterations, the agent will ask for guidance on reproduction steps.

Output

After completion, the agent reports:

• Files created
• Test verification result (FAIL = success for bug reproduction)
• Failure message (proof tests catch the bug)

File Locations

Test Type	Location
UI Tests - HostApp	src/Controls/tests/TestCases.HostApp/Issues/IssueXXXXX.cs
UI Tests - NUnit	src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/IssueXXXXX.cs
XAML Tests	src/Controls/tests/Xaml.UnitTests/Issues/MauiXXXXX.xaml[.cs]

Related Skills

• write-ui-tests - UI test creation
• write-xaml-tests - XAML unit test creation
• verify-tests-fail-without-fix - Test verification