Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
18 playbooks · 509 guides · 96 articles · 13 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
18 playbooks
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Cache Stampedes
How to recognize and contain request spikes when cached data expires.
Debugging CORS Origin Bugs
A practical way to inspect origin parsing, credentials, and header behavior.
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Timezone Bugs
Time bugs usually live at day boundaries, DST changes, and unit conversions.
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Structured investigations for the failure modes engineers meet in real systems.
Jest Module Mock Not Working: A Debugging Guide
A practical debugging guide for when Jest's jest.mock() doesn't actually mock the module, covering hoisting issues, path mismatches, and module caching.
Jest Fake Timers Not Advancing — Why setTimeout/setInterval Never Fire
A firefighting guide for when Jest's fake timers stall — timers don't advance, tests hang, or assertions time out. Covers the real root causes like legacy vs modern timer API, async gaps, and jest.useFakeTimers() placement.
Jest Async Test Timeout Exceeded: Root Causes and Debugging Steps
A practical guide to diagnosing and fixing Jest async test timeouts, covering promise hanging, done() misuse, and timeout configuration.
Vitest Coverage Not Collecting: Debugging Empty or Missing Coverage Reports
A direct guide to diagnosing why Vitest coverage reports come empty or missing, with concrete commands, config checks, and a real incident walkthrough.
Playwright Locator Not Found: Selector Timeout & Element Resolution
Diagnose and fix Playwright's 'locator not found' error with concrete debugging steps, common causes, and a production war story.
Playwright route.intercept Not Working: Silent Failures and Missing Requests
When route interception silently fails in Playwright, requests pass through unmodified. This guide covers real causes: glob patterns, method scope, page lifecycle, and route handler ordering.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Five Debugging Habits That Separate Seniors from Juniors
It's not tools. It's not years of experience. It's five repeatable habits that senior engineers do reflexively and juniors haven't built yet.
Why Your Production Logs Are Lying to You
Logs tell you what the code reported. They almost never tell you what actually happened. Here is the gap, and how to close it.
The Real Cost of Console.log Debugging (and What to Use Instead)
Every engineer reaches for console.log. Most do not think about what it costs — in time, in performance, or in production readiness. Here is the honest accounting.
Interpreting Stack Traces: Practical Steps for Faster Debugging
Stack traces can be dense, but reading them fluently accelerates triage and root cause analysis. This article explains how to extract actionable information, with real-world context.
Efficient Debugging with git bisect: Going Beyond Binary Search
This article explains how to incorporate git bisect into your debugging workflow, focusing on practical execution, automation, and common edge cases.
Applying Rubber Duck Debugging to Complex Engineering Problems
Rubber duck debugging isn’t just a quirky solo exercise. I’ll show how explaining code out loud surfaces misunderstandings and reduces wasted team cycles.