Scala exercise for Cengage's Friday afternoon polyglot jams. This will introduce you to TDD using Scala and ScalaTest
Rational-Scala is an exercise created for Cengage's "Friday Afternoon Polyglot Jam". The intent is to experience functional programming using Scala as well as some of the interesting features of the Scala language including operator overload.
- clone the project from GitHub (git://github.com/mikesmithson/Rational-Scala.git)
- Install sbt (http://www.scala-sbt.org/)
- run sbt from the cloned project
- type "test" from the sbt prompt
Running "test" from sbt will download dependencies (including Scala), compile the code and run the tests.
You should be rewarded with the message "[success]" and see no failed tests.
You are free to use the text editor of your choice. If you want to use eclipse, you can import the sbt project -- but first, you need to "eclipsify" the project. Just type "eclipse" from the sbt prompt. You should be rewared with the message "[info] Successfully created Eclipse project files for project(s)". Now you can import the project into eclipse. You will also want these eclipse plug-ins for eclipse: Scala IDE for Eclipse, and ScalaTest for Scala IDE. If you use Intellij-IDEA, just type "gen-idea" at the sbt prompt.
Scala IDE Ecosystem (Includes ScalaTest): http://download.scala-ide.org/ecosystem/dev-2.0-2.9/site/
Sbt Console for Eclipse: http://scala-ide.dreamhosters.com/nightly-update-sbtconsole-scalaide21-29/site/
Your task is to test-drive the Rational.scala class using the spec RationalSpec.scala as your guide for the typical red-green-refactor cadence. Sbt has the nice feature of ~test that listens for changes in your test/production code and re-runs all of your tests when you make a change. The operations to add, subtract, multiply, and divide your rational objects will also require that you also represent the result of the operation by finding it greatest common divisor. For example, 2/3 * 3/4 = 1/2. To give you a hint of how to do this, you should use Euclid's algortihm.
Eculid's algorithm can be pseudocoded as follows:
Step 1: given two integers p and q, define a function gcd(p,q)
Step 2: if q is 0 then return p
Step 3: else r = p mod q
Step 4: re-evaluate Step 1 as gcd(q,r)
Spoiler Alert -- the file RationalSolution.txt contains my solution. This is meant as a guide only. Your mileage may vary.
Feel free to log an issue if you are not sure. Rational.scala is taken directly from Martin Odersky's excellent book -- "Programming in Scala, Second Edition".