MCPBridge TestRunnerTools Performance Degradation in Unity Test Runs

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Created 7 days ago

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Investigation summary

The MCPBridge TestRunnerTools in com.meta.xr.sdk.core version 205.0.0 causes severe performance degradation in Unity test runs due to two defects: (1) OnTestFinished re-serializes the entire accumulated result list to EditorPrefs on every test completion, creating O(n²) overhead on the main thread; (2) _cachedResults is never cleared between runs except when using the MCP tool entry point, causing unbounded accumulation. This results in significantly increased test run duration, with one test suite growing from 10s to over 3 hours, and EditorPrefs reaching 26MB and 103,800 records, with 99.8% of wall-clock time spent on callback overhead. This issue affects both EditMode and PlayMode tests run from the Test Runner window or batchmode, and is observed in Unity version 6000.6.0f1 on Windows 11.