Add maven wrapper and tests

Author: kappsegla

.mvn/wrapper/maven-wrapper.properties

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+wrapperVersion=3.3.4
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.11/apache-maven-3.9.11-bin.zip

README.md

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-# 🚀 Requirements
+# Warehouse Kata – Instructions
 
-Add requirements here
+Welcome! In this exercise you will implement a small domain around a Warehouse with products. Your goal is to:
+- Create and complete several classes/interfaces under src/main/java that are currently missing or partially implemented.
+- Pick correct data types for parameters and return values so the project compiles and tests can run.
+- Make all tests in BasicTest green first.
+- Commit after major steps. When all BasicTest tests are green, push your commits.
+- Extra credit: implement the advanced features so that EdgeCaseTest is also green.
+
+## 1) Getting started
+1. Open this project in your IDE (IntelliJ IDEA recommended).
+2. Ensure you have JDK 25.
+3. Build once to see current state:
+   - ./mvnw compile
+
+## 2) What you will need to create/finish
+You will work primarily in src/main/java/com/example. Some files already exist but contain TODOs or empty methods. Implement the following:
+
+- Category (value object)
+  - Use a private constructor and a public static factory Category.of(String name).
+  - Validate input: null => "Category name can't be null"; empty/blank => "Category name can't be blank".
+  - Normalize name with initial capital letter (e.g., "fruit" -> "Fruit").
+  - Cache/flyweight: return the same instance for the same normalized name.
+
+- Product (abstract base class)
+  - Keep UUID id, String name, Category category, BigDecimal price.
+  - Provide getters named uuid(), name(), category(), price() and a setter price(BigDecimal).
+  - Provide an abstract String productDetails() for polymorphism.
+
+- FoodProduct (extends Product)
+  - Implements Perishable and Shippable.
+  - Fields: LocalDate expirationDate, BigDecimal weight (kg).
+  - Validations: negative price -> IllegalArgumentException("Price cannot be negative."); negative weight -> IllegalArgumentException("Weight cannot be negative.").
+  - productDetails() should look like: "Food: Milk, Expires: 2025-12-24".
+  - Shipping rule: cost = weight * 50.
+
+- ElectronicsProduct (extends Product)
+  - Implements Shippable.
+  - Fields: int warrantyMonths, BigDecimal weight (kg).
+  - Validation: negative warranty -> IllegalArgumentException("Warranty months cannot be negative.").
+  - productDetails() should look like: "Electronics: Laptop, Warranty: 24 months".
+  - Shipping rule: base 79, add 49 if weight > 5.0 kg.
+
+- Interfaces
+  - Perishable: expose expirationDate() and a default isExpired() based on LocalDate.now().
+  - Shippable: expose calculateShippingCost() and weight() (used by shipping optimizer in extra tests).
+
+- Warehouse (singleton per name)
+  - getInstance(String name) returns the same instance per unique name.
+  - addProduct(Product): throw IllegalArgumentException("Product cannot be null.") if null.
+  - getProducts(): return an unmodifiable copy.
+  - getProductById(UUID): return Optional.
+  - updateProductPrice(UUID, BigDecimal): when not found, throw NoSuchElementException("Product not found with id: <uuid>"). Also track changed products in getChangedProducts().
+  - expiredProducts(): return List<Perishable> that are expired.
+  - shippableProducts(): return List<Shippable> from stored products.
+  - remove(UUID): remove the matching product if present.
+
+- WarehouseAnalyzer (extra credit)
+  - Implement the advanced methods used by EdgeCaseTest: price-range search (inclusive), expiring-within-days, case-insensitive name search, above-price search, weighted average per category (round to 2 decimals), price outliers (population stddev), shipping group optimization (first‑fit decreasing by weight), expiration-based discounts, inventory validation summary, and inventory statistics.
+
+## 3) Workflow to follow
+1. Implement the missing classes/interfaces and methods so the project compiles.
+2. Run tests:
+   - Basic first: ./mvnw -Dtest=BasicTest test
+   - When green, commit with a clear message.
+3. Extra credit: make EdgeCaseTest green:
+   -  ./mvnw -Dtest=EdgeCaseTest test
+4. Commit after each major milestone (e.g., "Implement Product & FoodProduct", "Warehouse behaviors", "Analyzer advanced features").
+5. Push when BasicTest is fully green (and EdgeCaseTest too if you do the extra credit).
+
+## 4) Tips
+- Prefer BigDecimal for prices and weights (exact values in tests). Where an interface requires Double (e.g., weight()), convert BigDecimal to double on return.
+- Always round monetary results to 2 decimals using HALF_UP when tests assert exact values.
+- Keep public APIs exactly as tests expect (method names, exception messages).
+- Ensure Warehouse.clearProducts() is called in tests; do not share state between tests.
+
+Good luck and have fun!