Google Releases Auto-Diagnose: LLM-Based System for Diagnosing Integration Test Failures at Scale

Google AI has released Auto-Diagnose, an LLM-based system that automatically diagnoses integration test failures by analyzing logs and posting root cause findings directly into code reviews. Using Gemini 2.5 Flash with prompt engineering rather than fine-tuning, the system achieved 90.14% accuracy in identifying root causes across 71 real-world failures spanning 39 teams. Since launching in production in May 2025, Auto-Diagnose has processed 224,782 test executions across 91,130 code changes from 22,962 developers, ranking 14th in helpfulness among 370 tools in Google's Critique system with 84.3% of feedback requesting continued use. The system addresses a major productivity pain point identified in Google surveys, where 38.4% of integration test failures take over an hour to diagnose and the issue ranked among the top five developer complaints in a company-wide survey of 6,059 engineers.

Auto-Diagnose System Architecture and Technical Implementation

• ▪Auto-Diagnose post-processes the model's response into markdown with Conclusion, Investigation Steps, and Most Relevant Log Lines sections
• ▪Gemini 2.5 Flash was not fine-tuned on Google's integration test data for Auto-Diagnose
• ▪Auto-Diagnose calls Gemini 2.5 Flash with temperature set to 0.1 and top p set to 0.8

Performance Metrics and Production Deployment Results

• ▪Auto-Diagnose has been in production since May 2025
• ▪Auto-Diagnose received 517 total feedback reports from 437 distinct developers
• ▪436 of Auto-Diagnose's feedback reports were Please fix from 370 reviewers, representing 84.3% of total feedback
• ▪Auto-Diagnose has a Not helpful rate of 5.8% based on feedback received
• ▪Auto-Diagnose has a helpfulness ratio of 62.96% among developer-side feedback
• ▪Auto-Diagnose has run on 52,635 distinct failing tests across 224,782 executions on 91,130 code changes authored by 22,962 distinct developers
• ▪Auto-Diagnose ranks number 14 in helpfulness across 370 tools that post findings to Critique, placing it in the top 3.78%
• ▪Auto-Diagnose averages 110,617 input tokens and 5,962 output tokens per execution
• ▪Auto-Diagnose correctly identified the root cause 90.14% of the time in a manual evaluation of 71 real-world failures spanning 39 distinct teams
• ▪Auto-Diagnose posts findings with a p50 latency of 56 seconds and p90 latency of 346 seconds

The Integration Test Debugging Problem at Google

• ▪A Google survey of 116 developers found that 38.4% of integration test failures take more than an hour to diagnose
• ▪A separate Google survey of 239 respondents found that 78% of integration tests at Google are functional
• ▪Diagnosing integration test failures showed up as one of the top five complaints in EngSat, a Google-wide survey of 6,059 developers

Perspective of Google developers using Auto-Diagnose

• ▪370 distinct Google developers submitted Please fix feedback for Auto-Diagnose, indicating they want to continue receiving its diagnoses

Perspective of Google AI researchers behind Auto-Diagnose

• ▪Google AI researchers validated Auto-Diagnose's 90.14% accuracy rate through manual evaluation across 39 distinct teams to ensure cross-team reliability

Perspective of Google engineering leadership

• ▪Google engineering leadership measures Auto-Diagnose success through its top 3.78% helpfulness ranking among 370 tools in the Critique code review system
• ▪Google engineering leadership deployed Auto-Diagnose to production in May 2025 after validating its performance across 22,962 distinct developers