Testing Simple Cases

Before testing complex inputs, always verify your code works with simple cases. If it fails on easy inputs, it will definitely fail on hard ones. Start Simple When testing a function that processes lists, try these in order: Example: Testing a function that finds the maximum: Edge Cases Matter Edge cases are inputs at the boundaries of what's valid. They're where bugs most commonly hide. Handling edge cases is not optional. It separates working code from production-ready code. The consequences of ignoring edge cases can be enormous. Testing with simple cases first -- empty, single element, two elements -- catches most bugs before you even reach complex inputs. Build this habit and you will spend far less time debugging later. Edge cases are where the gap between "working code" and "product

About This Interactive Section

This section is part of the Problem Solving: Beginner lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

How DataDriven Lessons Work

DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.