The ExpenseReport legacy code refactoring kata in various languages.
This is an example of a piece of legacy code with lots of code smells. The goal is to support the following new feature as best as you can:
- Add Lunch with an expense limit of 2000.
- 📚 Read the code to understand what it does and how it works.
- 🦨 Read the code and check for design and code smells. Make a list of all code and design smells that you find.
- 🧑🔬 Analyze what you would have to change to implement the new requirement without refactoring the code.
- 🧪 Write a characterization test. Expand your list of code and design smells. Add those smells that you missed earlier and discovered now because they made your life writing a test miserable.
- 🔧 Refactor the code.
- 🔧 Refactor the test.
- 👼 Test-drive the new feature.
To see solutions, switch to the solutions branch.
Warning The solutions branch will be rebased!
I first encountered the ExpenseReport example during a bootcamp at Equal Experts. I also have seen the ExpenseReport example being used by Robert "Uncle Bob" C. Martin. However, he seems to not be the original author (https://twitter.com/unclebobmartin/status/1537063143326855176?s=20&t=lh_vVb9jUQmY6PYG50974w) I have tried to research its origins but so far I have failed. If you know who has first come up with this example, please get in touch with me.
As I was asked for the license conditions, I have decided to put this under CC-BY-SA, with the following considerations:
- Please credit me, last but not least to retain the opportunity for people to experience this exercise in as many programming languages as they are interested in.
- Share it under the same license.
- Using this as training material should be allowed, even if the trainer is charging money for their time.
The ExpenseReport refactoring example in TypeScript.
- Typescript as the main programming language
- Jest as the testing framework
- Eslint as the linting tool
- Prettier as the formatting tool
- NVM installed on your machine from here
./configure.sh # will use nvm to install and activate the appropriate version of node
npm test # will run all the tests
npm bulid # will create a build of the project
node build/output.js # will run the compiled output
npm run format:check # runs the linter and formatter rules
npm run format:fix # applies a fix to the fixable issues