Test Automation
Every engineering team has a war story about cloud costs. A misconfigured NAT gateway left running over a weekend. An S3 bucket with lifecycle policies accidentally removed, slowly accumulating terabytes. A developer who switched from db.t3.micro to db.r6g.4xlarge "just to test" and forgot to
Clojure
Example-based tests verify that specific inputs produce specific outputs. They are good at documenting intended behavior and catching known regressions. What they cannot do is find the bugs you haven't thought of yet. Property-based testing flips the model: you describe invariants your code must always satisfy,
Clojure
Most Clojure developers learn deftest and is quickly, then stop. They write tests that look fine but miss the idioms that make large test suites maintainable, fast, and expressive. This post covers the patterns that separate workable test suites from great ones — fixtures that actually clean up, custom matchers that
QA Career
QA and SDET interviews are inconsistent. Some are almost entirely behavioral. Some are heavy on coding. Some give you a live application and ask you to find bugs. Some give you a take-home assignment that takes 10 hours. You can't prepare for a single format. What you
QA
Having a contract with a QA agency doesn't mean you have QA coverage. The difference between a productive outsourcing relationship and a frustrating one is workflow — how work flows between your team and theirs, how information gets communicated, and how you handle the inevitable coordination friction. Most outsourcing
Testing
Kaocha is the test runner that Clojure projects reach for when clojure.test and lein test stop being enough. It adds test suites, plugin architecture, a watch mode, and rich output formatting — while staying fully compatible with standard clojure.test tests. This guide covers the setup and patterns that matter
Testing
Claude has become one of the most effective tools for writing automated tests. Not because it's faster than other AI models — it's fast, but speed isn't the differentiator. Claude is effective for testing because it reasons about what should be tested before writing a
Python
Python profiling uses cProfile for deterministic function-level profiling, py-spy for low-overhead sampling profiling in production, and line_profiler for line-by-line analysis. This guide covers running each tool, reading pstats output, generating flame graphs, and profiling Django and FastAPI applications. Python's GIL (Global Interpreter
Testing
The Classification Tree Method (CTM), developed by Matthias Grochtmann and Klaus Grimm at Daimler-Benz Research in the early 1990s, is a structured approach to black-box test design that makes the input space visible. Unlike equivalence partitioning — which most testers apply informally and inconsistently — CTM gives you a formal
Testing
Data transformation bugs are silent killers. A shape mismatch, an off-by-one in a rolling window, a dtype coercion you didn't notice — these don't raise exceptions. They silently corrupt downstream models, dashboards, and decisions. This guide focuses on pytest patterns specifically for pandas and numpy
Testing
Data pipelines fail in ways that pure unit tests don't catch. A transformation that works on clean test data breaks on real-world schemas with extra columns, unexpected nulls, or timezone-aware timestamps. A join that looks correct drops 40% of rows silently. This guide covers pytest patterns
Python
pytest-BDD supports three layers of data-driven testing: Scenario Outlines in feature files, @pytest.mark.parametrize on scenario functions, and params on fixtures. Understanding when to use each — and how to combine them — is the key to eliminating test duplication without sacrificing readability. Key Takeaways * Scenario Outlines belong in