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.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
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Structured investigations for the failure modes engineers meet in real systems.
Tests pass locally but fail in CI: how to debug it
Green locally, red in CI. The diff is usually environment, ordering, or a clean-install gap. Here is how to narrow it down fast.
Flaky tests in CI: how to debug and fix intermittent test failures
A test passes nine times out of ten but randomly fails in CI with no code changes. Flaky tests destroy trust in the test suite — here is how to find and fix them.
Debugging Pytest Fixture Scope Mismatches
A practical guide to diagnosing and fixing fixture scope conflicts in pytest, covering shared state, teardown order, and concurrency issues.
Python Mock patch() Wrong Target: Why Your Mock Isn't Mocking
A debugging guide for when unittest.mock.patch doesn't work because the target string points to the wrong module path.
Debugging Go Test Race Conditions with t.Parallel()
A practical guide to diagnosing and fixing race conditions that appear when running Go tests with t.Parallel(), covering false sharing, shared state, and flaky CI failures.
GitHub Actions Workflow Failing: Debugging Steps That Actually Work
A step-by-step guide to debug failing GitHub Actions workflows, covering common pitfalls like caching, permissions, and runner issues.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Mocking External APIs in Tests: Why stubbing HTTP is harder than it looks
Stubbing HTTP calls seems easy until a subtle mismatch between your mock and the real API causes a production incident. Here's what I learned the hard way.
How I Diagnosed a 1-in-1000 Race Condition in Our CI Pipeline
A race condition that only appeared once every thousand CI runs took weeks to track down. Here's how we finally caught it, what tools helped, and what we changed to prevent similar bugs.
Debugging Flaky Tests for Good: A Systematic Approach to Root Cause Analysis
Flaky tests waste time and erode trust. Here's how to find and fix the actual root cause instead of just rerunning.