Summary

When running EditMode tests via MCP with a dirty scene, Unity's "Save Scene" modal dialog blocks the editor event loop, causing MCP to timeout without receiving a response.

Root Cause

In TestRunnerService.RunTestsAsync(), the SaveDirtyScenesIfNeeded() method is only called for PlayMode tests:

// Current code (line 109-112)
if (mode == TestMode.PlayMode)
{
    SaveDirtyScenesIfNeeded();
}

This means EditMode tests don't auto-save dirty scenes, and Unity's test framework triggers a modal save dialog that blocks the entire editor.

Steps to Reproduce

1. Open a Unity project with MCP-for-Unity installed
2. Make changes to the current scene (scene becomes dirty)
3. Call run_tests with mode: "EditMode" via MCP
4. Observe: Unity shows "Save Scene" modal dialog
5. Result: MCP times out waiting for response

Expected Behavior

EditMode tests should auto-save dirty scenes before running, just like PlayMode tests do.

Proposed Fix

Move SaveDirtyScenesIfNeeded() outside the PlayMode conditional so it runs for all test modes:

// Before _testRunnerApi.Execute(settings):
SaveDirtyScenesIfNeeded();  // Save for ALL test modes, not just PlayMode

This is a one-line change in TestRunnerService.cs.

Environment

• Unity MCP version: 8.7.1
• Unity version: 6.3 LTS
• MCP Client: Claude Code

Workaround

Manually save all scenes before running tests, or create a [InitializeOnLoad] script that registers a ICallbacks handler to auto-save on RunStarted.