The Merchant’s Guide to the Galaxy

Sample command-line application to solve "The Merchant’s Guide to the Galaxy" coding problem.

To run it, execute:

./run.sh merchants.txt

Requirements

This is a Java 8 console application, built and run with maven.

Notes

See TODO to follow development steps. For an overall view of the application, see acceptance tests. See individual unit tests for deailed behaviour examples.

I tried to split the problem in two iterations:

• first, achieve and end-to-end version, using Arabic numerals, simpler to implement. For example, I've used it for testing other responsibilities in isolation, such as actions and prices.
• then, implement Roman numerals, and bind to main application. This was the very first moment when acceptance tests were executed, providing feedback on the complete problem.

In dummies test package you can find such simpler implementation of application roles (as for Arabic numerals, and in-memory I/O).

Resulting design is composed of a main application object, delegating each content line processing to matching actions. Each action can then prepare shared state (being commands) or add info to result (being queries). Matching action is detected applying a regexp pattern on line content. A fallback action is provided, to handle unrecognized line content.

Final notes, given examples to support were very simple:

• prices are represented by big decimals, but no particular rounding was required
• Roman numerals implementation is very basic, no special rules on symbols subtraction

Feel free to provide any feedback!