Java 8+ Practice Project

A hands-on learning project exploring Java 8+ features through practical, real-world examples.
Topics covered: Optional, Function (Functional Interface), JUnit 5 tagging, and CI/CD basics.

---

📚 What Is This Project?

See docs/WHAT_IS_IT.md for a full overview of the project goals and structure.

---

📂 Project Structure

src/
├── main/java/
│   ├── functionalInterface/function/myimpl/   ← Function<T,R> interface demo
│   ├── optionaldemoone/                        ← Optional with real-world domain objects
│   └── jenkins/                               ← CI/CD placeholder
└── test/java/
    ├── junitdemo/                              ← JUnit 5 Tags & Display Names
    ├── optionaldemoone/                        ← Tests for DiscountService
    └── optionaldemoWithPerson/                 ← Optional stream scenarios

---

🗂️ Learning Guides

Guide	Description
docs/WHAT_IS_IT.md	Project overview and learning goals
docs/optional-guide.md	Deep dive into Java Optional
docs/advanced-optional-scenarios-explained.md	Advanced Optional patterns explained in depth
docs/functional-interface-function-guide.md	Function<T,R>, andThen, compose
docs/junit5-tagging-guide.md	JUnit 5 @Tag, @DisplayName, selective test runs
docs/java21-modern-java-guide.md	Java 21 features used in this project
docs/github-actions-guide.md	GitHub Actions explained for beginners
docs/github-actions-advanced-guide.md	Advanced GitHub Actions — concurrency, secrets, matrix, artifacts, reusable workflows

---

🚀 Running the Project

Prerequisites

• Java 21+
• Maven 3.6+

Run All Tests (locally)

mvn test

Run Tests by Tag (locally)

# Run integration tests only
mvn test -Dgroups="integration"

# Run unit tests only
mvn test -Dgroups="ecomm-unit-tests"

# Run sanity tests only
mvn test -Dgroups="ecomm-sanity"

# Run Optional demo tests
mvn test -Dgroups="Rel1"

Pass Custom System Properties

mvn test -DinParameter=MyValue

🤖 Run via GitHub Actions (CI/CD)

Workflow	Trigger	What it runs
CI — Build & Test All	Auto on every push & PR	All tests
Ecommerce — Unit Tests	Manual (Actions tab)	@Tag("ecomm-unit-tests")
Ecommerce — Sanity Tests	Manual (Actions tab)	@Tag("ecomm-sanity")
Run Tests by Tag	Manual with input	Any tag you specify

📖 New to GitHub Actions? See docs/github-actions-guide.md for a full walkthrough.

---

🛠️ Tech Stack

Technology	Version	Purpose
Java	21 (LTS)	Language — enables records, switch expressions, var, .toList(), text blocks, and more
Maven	3.6+	Build tool
JUnit Jupiter	5.10.2	Unit testing framework
AssertJ	3.19.0	Fluent assertions