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, nextestallfeatures, 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