detect-flaky-tests

name	detect-flaky-tests
description	Identify flaky tests by comparing failures across multiple CI runs. Use when the user suspects flaky tests, sees intermittent failures, or wants to analyze test reliability.

Detect Flaky Tests

Identify flaky tests by comparing failures across multiple CI runs.

Prerequisites

• gh CLI installed and authenticated (gh auth login)

Instructions

Step 1: Get Recent Workflow Runs

Get last N runs from the specified branch (default: dev):

gh run list --workflow=Rust --branch=dev --limit=10 --json databaseId,conclusion,headSha,createdAt

Step 2: Download Failed Job Logs

For each run, get failed test jobs only (nextest, nextest_all_features, coverage):

gh run view <run-id> --json jobs --jq '.jobs[] | select((.name == "nextest" or .name == "nextest_all_features" or .name == "coverage") and .conclusion == "failure") | {id: .databaseId, name: .name}'

Download logs to ci-logs/flaky-analysis/run-<run-id>/:

gh run view --job <job-id> --log | perl -pe 's/\e\[[0-9;]*m//g' > ci-logs/flaky-analysis/run-<run-id>/<job_name>.log

Step 3: Extract Failed Tests

Parse each log for failed test names. Look for patterns:

• FAILED followed by test path
• test result: FAILED
• Specific test framework output patterns

Step 4: Correlate Failures

Build a matrix: test name vs run ID (pass/fail).

Identify:

• Flaky tests: Fail in some runs, pass in others
• Consistently failing: Fail in all/most runs (real bugs)
• New failures: Only fail in recent runs

Step 5: Report

Provide summary:

• List of flaky tests with failure rate (e.g., "failed 3/10 runs")
• List of consistently failing tests
• Recommendations:
  • Flaky tests to investigate or quarantine
  • Real failures to fix

Notes

• Run this on dev to detect flakiness independent of PRs
• Consider running on PR branches to check if PR introduced flakiness