software-engineering-lessons

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Engineering Lessons

A polyglot mono-repo to help software engineers grow in length and breadth — TDD, DSA, language playgrounds, system design, devops, and CI/CD, each as a standalone module with its own toolchain.

For an agent-friendly walkthrough (layout, build commands per module, conventions), see CLAUDE.md.

Quick walkthrough

Module	What’s inside
agile/tdd/	Live TDD demos in Java with JUnit/Mockito/AssertJ — auth, checkout, generic
dsa-kotlin/	Data structures & algorithms in Kotlin (Maven + JUnit5)
code/fun-with-golang/	Go-by-example walkthrough (see GOLANG_EXAMPLE.md for the checklist)
code/fun-with-kotlin/	Functional-style Kotlin
code/fun-with-python/	Dockerized Jupyter, GenAI labs (FFT/PEFT, ROUGE/BLEU), LLM playgrounds, CLI
code/fun-with-typescript/	TS basics & pre-requisites
code/fun-with-shell-script/	adb bulk export/delete helpers
system-design/	Fundamentals — hash functions, URL redirect router (Go + Java)
devops/	Linux & CI/CD cheatsheets
hooks/, scripts/	Git hooks + helper scripts wired by install-hooks.sh

Topic checklist

• agile
  • tdd
• code
  • fun-with-golang
  • fun-with-kotlin
  • fun-with-python (Jupyter, GenAI labs, LLM setups)
  • fun-with-typescript
  • fun-with-shell-script
• system-design (hash functions, redirect short url)
• devops
  • linux (cheatsheet)
  • ci-cd (cheatsheet)
• dsa-kotlin
  • easy
  • medium
  • hard
• hooks — git hooks utility to execute checks before commit/push
• scripts
  • install-hooks.sh
  • run-branch-name-check.sh
  • run-tests.sh

Install pre-commit + pre-push hooks

Runs mvn test for agile/tdd and dsa-kotlin before every commit, and validates branch name before every push.

sh scripts/install-hooks.sh

Branch naming rule

Branches must start with one of:

HEAD | feature | hotfix | conflict | bumpversion | revert | bug | fix | release | doc

Examples: feature-go, feature/go-channels, fix-build-ci, doc/readme.

Running tests

# Aggregate (tdd + dsa, same as pre-commit hook)
sh scripts/run-tests.sh

# Per-module
mvn test --file agile/tdd/pom.xml
mvn test --file dsa-kotlin/pom.xml
mvn test --file code/fun-with-kotlin/pom.xml
mvn test --file system-design/topics/pom.xml

cd code/fun-with-golang && go test ./...

CI (.github/workflows/build-ci.yml) is path-filtered — it only tests modules whose files changed in the PR. Markdown-only PRs skip CI.

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