Computer Science
Testing & QA Challenges
Testing & QA challenges put you behind the safety net that lets software ship with confidence. You'll develop skills in Software Testing, Unit Testing, and Automated Testing, build End-to-end testing flows, and read Coverage Reports to find the gaps that matter before users do.
From there you'll handle the harder edges — Test architecture, Test pyramid discipline, Contract testing, and Load Testing — alongside Static Analysis, AI-assisted test generation, and regulated practices like ISO 17025 calibration and CAPA workflows. Each challenge you solve earns a verified credential you can share with recruiters.
Recommended Challenges
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Design TaskFlow's Pricing-Page Experiment Verdict and Decision Proposal
Working only from the two provided materials — the visitor-level experiment dataset (`ab_test_visitors.csv`) and the VP decision brief (`vp_decision_brief.md`) — design a propos…
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Rule on TaskFlow's Enterprise Landing Page A/B Test
Working only from the test results dataset and the test-setup brief in the provided materials, determine whether the redesigned page genuinely improves the demo-booking conversi…
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Add a Test Harness to an Untested Open-Source CLI
Fork the repo (test mirror provided), set up Vitest with coverage and a CI workflow that fails under 75 percent on the targeted modules. Write characterization tests first (asse…
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Software Construction - CodeIntermediateNew
Code Review and Refactoring of a Legacy E-Commerce Module
You are given a codebase (Java/Spring Boot) of the order module. Perform a static analysis, document issues (e.g., god classes, tight coupling), and write a refactoring proposal…
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Open coursework Develop in-demand professional skills.
Each challenge names the skills it strengthens. Over time, your profile fills with the competences a hiring manager would actually look for.
Why Ewance
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Build a Hybrid Recommender for a Niche Consumer-AI Music App
You receive listening events (around 240 million plays) plus a content embedding per track (audio + curator tags). Build a collaborative filtering model (ALS or implicit-feedbac…
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Build a Forgetting-Curve-Aware Spaced-Repetition Engine
You receive 6 months of practice logs from 8,000 learners (item, timestamp, response correctness, response latency). Fit a learner-personalized forgetting model (logistic per-it…
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Open coursework - DesignBeginnerNew
Add Constant Folding and Dead Code Elimination to a Teaching Compiler
Using the provided intermediate-representation specification, design and propose constant folding and dead code elimination as two intermediate-representation-to-intermediate-re…
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Open coursework - StrategyBeginnerNew
Nudge Strategy for a Bangalore D2C Cosmetics Brand
You are a behavioral economics consultant hired by Glow Naturals. Analyze their current checkout process (provided in a mockup) and identify cognitive biases causing friction. P…
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Open coursework - Browse challenges
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Strategy Analyst
Frame the business question, model the options, build the recommendation. From market sizing to competitive analysis, this role is where strategy consulting meets in-house decision-making.
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Build a Plugin-Based Notification Framework With Observer + Factory
Implement, in Java 21: an EventBus that supports typed subscriptions, a NotificationChannel interface with concrete subtypes (Push, Email, InApp, SMS), an AbstractChannelFactory…
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Object-Oriented Programming and Design - AnalysisFoundationalNew
Optimize Ad Spend for Munich D2C Cosmetics Brand
You are given a CSV dataset with 10,000 rows of ad performance data including date, campaign, audience segment, creative type, impressions, clicks, conversions, and spend. Your …
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Open coursework - CodeBeginnerNew
Design a Domain Model for a Library Loan System (Java)
Implement, in Java 21, an Item type hierarchy (Book, AudioBook, Periodical, EquipmentLoan — each with sub-type-specific rules), Member with eligibility logic, Loan as an aggrega…
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Right-Size a Real-Time Recommendation Serving Cluster
You receive 7 days of request-level telemetry (timestamp, latency, error code, pod) plus the existing Horizontal Pod Autoscaler (HPA) and node-group configs. Analyze traffic pat…
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Machine Learning at Scale Get recognized by recruiters and employers.
Credentials are blockchain-anchored via LearnCoin — tamper-evident, portable, link-shareable on LinkedIn and beyond.
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Design a Playwright Checkout Test Suite That Blocks Bad Merges
Using the checkout incident export, identify the single most valuable happy path plus the six edge cases tied to the most frequent and most severe past incidents (for example fa…
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Open coursework - CodeIntermediateNew
Apply Hexagonal Architecture to a Payments Microservice
Design the settlement domain in pure Kotlin (no Spring imports, no framework annotations). Define ports for: payment-network adapter (one inbound per network — SEPA, Faster Paym…
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Domain-Driven Design - AnalysisSeniorNew
Cost-Quality Prompt Optimization at Scale
You receive 2,000 labeled code snippets (human rater consensus score 1-5) and budget for at most 8,000 API calls across the optimization run. Run a factorial sweep of 3 prompt s…
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Stand Up Contract Testing for a Logistics Microservices Backend
Using only the materials provided, choose and justify the six producer-consumer service pairs to migrate first. Read the 90-day staging breakage log to rank pairs by how much pa…
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Open coursework - DesignSeniorNew
Migrate a 600K-LOC Monolith to a Modular Monolith
Run static dependency analysis on the monolith (using Packwerk + custom Ruby AST scripts, both available) to surface the current implicit modules and the worst cross-module depe…
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Advanced Software Engineering - AnalysisBeginnerNew
Run an A/B Test on Two System Prompts for a Sales Email Assistant
You will (1) design the A/B test (random assignment by rep_id, 50/50 split, 2-week duration), (2) instrument three primary metrics: reply rate (event-based), average tokens per …
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Containerized Model Inference on Kubernetes for a Fintech
You receive a pre-trained credit-risk model (a LightGBM model file) and a sample request payload. Containerize a FastAPI inference service, deploy to EKS or GKE (a single-zone c…
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Design and Implement a C++ Telemetry Aggregator With Inheritance
Implement a TelemetrySource abstract base class with virtual sample() and timestamp() methods, 6 concrete subclasses (one per sensor family), and a TelemetryBus that polymorphic…
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Object-Oriented Programming and Design
How it works
From brief to credential, in six steps.
Step 01
Browse challenges aligned to your studies.
Step 02
Accept the one that fits your goals.
Step 03
Work through it with AI Copilot guidance.
Step 04
Submit for structured evaluation.
Step 05
Earn a verified credential.
Step 06
Add it to LinkedIn with one click.
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