New Module

# New Module: $ARGUMENTS

Create a complete, production-quality curriculum module. Follow every step in order. Do not skip steps.

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## Step 1 — Pre-flight

1. Read `PROGRESS.md` and locate the row for module `$ARGUMENTS` (match by module number or directory name).
   - Extract: **module number**, **directory name**, **curriculum section** (e.g., `4.2 Functional Interfaces`)
2. Read `CLAUDE.md` — specifically these sections:
   - "Module Structure Pattern"
   - "Package Naming Convention"
   - "Testing Best Practices"
   - "Content Creation Guidelines"
   - "Module Completion Checklist"
3. Verify the module directory does NOT already exist. If it does, validate it instead with `/validate-module`.

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## Step 2 — Claim

Update `PROGRESS.md`: change this module's status from `⬜ pending` → `🔄 in-progress`.

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## Step 3 — Register in Parent POM

Add the module to the root `pom.xml` `<modules>` section (in numeric order):
```xml
<module>{module-dir}</module>

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Step 4 — Create Module Skeleton

Create the following (substitute {pkg} = module directory name with hyphens removed, lowercase):

{module-dir}/
├── pom.xml                          ← copy structure from an existing module, update artifactId
└── src/
    ├── main/java/com/github/msorkhpar/claudejavatutor/{pkg}/
    └── test/java/com/github/msorkhpar/claudejavatutor/{pkg}/

pom.xml rules:

• <artifactId> = module directory name (e.g., 14-functional-interfaces)
• <name> = human-readable topic name
• Parent = com.github.msorkhpar.claudejavatutor:claude-java-tutor
• Include dependency on 00-base only if performance tests are needed

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Step 5 — Write Documentation

Before writing anything, read the entire 13-lambda-expressions/ module:

• README.md — it is a table-of-contents only (numbered list with links)
• README_4.1.1.md through README_4.1.4.md — these are the detailed per-sub-topic files; match their depth exactly

5a. Create README.md (table of contents only)

{module-dir}/README.md must be a numbered list of sub-topics with links to their README_X.Y.Z.md files. No content goes in README.md itself — only the ToC link list.

5b. Create README_X.Y.Z.md for EACH sub-topic (mandatory — no exceptions)

For every sub-topic listed under this section in CLAUDE.md, create a dedicated file (e.g., README_4.2.1.md).

Each file MUST contain ALL of these sections with deep, thorough content:

1. ## Concept Explanation — thorough explanation with a real-world analogy that makes the concept accessible
2. ## Key Points to Remember — bullet list of the most critical facts an interviewer expects you to know
3. ## Relevant Java 21 Features — how this concept evolved across Java versions, modern practices
4. ## Common Pitfalls and How to Avoid Them — numbered list; each pitfall shows the broken code AND the fix
5. ## Best Practices and Optimization Techniques — production-quality guidance, performance implications
6. ## Edge Cases and Their Handling — null inputs, empty collections, boundary conditions with code
7. ## Interview-specific Insights — what interviewers actually focus on, tricky questions to expect, whiteboard tips
8. ## Interview Q&A Section — minimum 5 Q&A pairs per sub-topic:
   • Each Q&A must have BOTH a \``textblock (explanation) AND a```java` block (code example)
   • Answers must be detailed — a paragraph of explanation, not a one-liner
9. ## Code Examples — links to the implementation and test source files

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Step 6 — Implement (TDD — repeat for EACH sub-topic)

For each sub-topic in the curriculum section:

6a. Write test class first

• File: src/test/java/.../ClassNameTest.java
• Use JUnit 5 + AssertJ
• Cover: happy paths, edge cases, null/empty inputs, expected exceptions, boundary conditions
• Use DataFaker for realistic data where appropriate

6b. Write implementation class

• File: src/main/java/.../ClassName.java
• Minimal code that clearly demonstrates the concept
• Use Java 21 features where appropriate

6c. Run tests immediately after each class pair

mvn test -pl {module-dir}

6d. Fix failures before moving to the next sub-topic

• Read the full stack trace
• Fix the root cause (never suppress or skip tests)
• Re-run until green
• Do not proceed to the next sub-topic until all current tests pass

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Step 7 — Final Validation

Run the validation script:

bash scripts/validate-module.sh {module-dir}

Fix every reported ERROR. Re-run validation until it exits with RESULT: PASS.

Run one final clean test:

mvn test -pl {module-dir}

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Step 8 — Complete

Update PROGRESS.md: change status from 🔄 in-progress → ✅ done.

Print a completion summary:

• Module: {module-dir}
• Curriculum section covered: {section}
• Implementation classes: list all
• Test classes: list all
• Total @Test methods written
• Validation result