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.

1. 📚 Read the code to understand what it does and how it works.
2. 🦨 Read the code and check for design smells.
3. 🧑‍🔬 Analyze what you would have to change to implement the new requirement without refactoring the code.
4. 🧪 Write a characterization test. Take note of all design smells that you missed that made your life writing a test miserable.
5. 🔧 Refactor the code.
6. 🔧 Refactor the test.
7. 👼 Test-drive the new feature.

The ExpenseReport example currently exists in the following languages:

• BASIC (Amiga BASIC, Commodore Amiga) ⇐ Quite amazing! First BASIC without line numbers!
• BASIC (Bywater BASIC, Linux) (very similar to Commodore BASIC)
• BASIC (Commodore BASIC, Commodore 64)
• BASIC (Locomotive BASIC, Amstrad CPC)
• C
• C#
• C++
• Clojure ⇐ This one was particularly painful to intentionally write poorly, I almost cried.
• COBOL
• Dart
• F#
• Fortran
• Go
• Groovy
• Java
• JavaScript
• Kotlin
• Lisp (Common Lisp)
• Lua
• Objective-C
• Pascal
• Perl
• PHP
• Prolog
• Python
• Raku (Perl6)
• Rexx (tested with Regina Rexx and ARexx)
• Ruby
• Rust
• Scala
• Scheme
• SQL (Using SQLite3)
• Swift
• Smalltalk
• TcL
• TypeScript
• Visual BASIC
• XML/XSLT

(in no particular order and with no guarantee)

• Ada
• D
• Eiffel
• Elixir
• Elm
• Erlang
• Haskell
• Julia
• Logo
• Modula-2 (once the linker starts working again)
• Oberon
• R

• Brainfuck
• Malbolge
• Whitespace

To see solutions, switch to the branch solutions.

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. 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.