christiangarcia/redbadger

RedBadger

• This solution showcases a TDD approach to implementing business logic, as seen in the commit history.
• Especial attention has been put to handle edge cases:
  • Incomplete input: Robot ignored
  • Invalid input: Error logged (using Timber) and displayed
  • Empty lines in input
• I/O is performed using InputStream and OutputStream, so that I/O operations can be executed on diverse types (files, plain Strings, etc) and decided on the call site client.
• I/O uses Reader#useLines() as opposed to Reader#readLines() to allow for very large inputs.
  • readLines reads all lines eagerly as a List<String>
  • useLines reads lines lazily as a Sequence<String>
  • This allows us, for example, to write into a file while reading the input file, without having to read the whole input file at once into memory.
• Because the core logic uses plain Kotlin, this test can be executed either as:
  • An Android app with UI (by launching the app module)
  • A standalone class (by launching Main.kt)
• DI using Dagger-Android

Android app

Uses architecture components to interact between UI and business logic:

Data binding <-> ViewModel <-> Flow (coroutines) <-> Business logic

Standalone Main class

Reads and writes to files

app/src/main/res/raw/robots_input.txt -> app/build/robots_output.txt)