dekay2323/RomanNumerals

Roman Numeral Converter

Roman Numeral Convertor

By D Krige

Can convert to and from Simple Roman Numerals (subtractive notation).

• You can see it running here
  • http://romannumerals.us-east-1.elasticbeanstalk.com/
• You can call it via json at
  • http://romannumerals.us-east-1.elasticbeanstalk.com/romanNumeral/calculate.json?romanNumeral=IV
  • http://romannumerals.us-east-1.elasticbeanstalk.com/romanNumeral/calculate.json?number=7

How to run

• Using SDKman http://sdkman.io/
  • Download Gradle 2.13
  • Download Grails 3.1.8
  • Download Groovy 2.4.4

Tests

• In the project directory
• grails clean
• grails test-app
• You can see the test results in /build/reports/tests/index.html

Run locally (containerless)

• In the project directory
• grails run-app
• Go to http://localhost:8080

Key files

• Test/Specification /src/test/groovy/com/strata/RomanNumeralConverterSpec.groovy
• Converter /src/main/java/com/strata/RomanNumeralConverterImpl.java

Overall

Development Process

• Used IntelliJ which I love.
• Gradle for builds
• Java 8
• Groovy 3
• Development time was roughly 10hours

Thoughts

• Fan of test driven development
• I like to spike, and let the code help me find the answer
• No side effects, as little state as possible
• Not a fan of comments, the tests and code should serve as documentation
• I like to commit to git a lot

Solving the problem

• In the real world I probably would have eventually Googled for Roman Numeral converters, as there are probably many interesting ways to solve this.
• Obviously for this test I did not do that and just developed my own.

Spike

• Setup GitHub https://github.com/dekay2323/RomanNumerals (private)
  • You can follow my commits there, I tend to commit a lot.
• Started with a test, I used the Spock testing framework http://spockframework.org/spock/docs/1.1-rc-2/index.html
  • Downloaded the Spock minimal example https://github.com/spockframework/spock-example
  • This gives me a gradle spock build
  • I find Spock the easiest testing framework to use, where your tests become documentation
  • It also handles Java and Groovy
• I used Groovy to sketch out and think through the problem
  • I just did the Groovy solution code directly in the test. I find this the fastest way to get instant feedback, also easy to debug
  • Groovy is very fast for spikes/prototypes and as it is a superset of Java it follows java closely, but gives lots of sugar. Pure Java code can run directly in Groovy files.
  • I use Groovy often to think through problems, its syntax seems closest to how I think. It is also very easy to create the Java from the Groovy (including Java 8, lambda, closures, higher order functions)
• Once I had tests and the Groovy reasonable, I moved to Java.
• Got all the tests running on the Java code

Webapp

• I created a simple Grails project (in Intellij or simple grails create-app)
  • I choose Grails as it is Spring Boot, with Convention over Code making for Rapid Application Development
  • Works seamlessly with Java
  • Containerless
• Started on the web interface
• A little bit of Jquery
• Worked on error handling and displaying the errors
• Deploy to Amazon EC2 http://romannumerals.us-east-1.elasticbeanstalk.com/
• Created json end point for calculation using same code as html
  • http://localhost:8080/romanNumeral/calculate.json?number=7
  • http://localhost:8080/romanNumeral/calculate.json?romanNumeral=IV

Tests

• Ran test coverage, RomanNumeralConverterImpl 100%
• I did NOT include controller tests, as these are very Grails specific

Improvements

• I would imagine the convertor algorithm could be more efficient
• Java 8 streams, maybe concurrent