add gcd

Author: andersonkmi

src/main/scala/org/codecraftlabs/training/Rational.scala

@@ -1,10 +1,13 @@
 package org.codecraftlabs.training
 
+import scala.annotation.tailrec
+
 class Rational (n: Int, d: Int) {
   require(d != 0)
 
-  val numer: Int = n
-  val denom: Int = d
+  private val g = gcd (n.abs, d.abs)
+  val numer: Int = n / g
+  val denom: Int = d / g
 
   def this (n: Int) = this(n, 1)
 
@@ -17,4 +20,9 @@ class Rational (n: Int, d: Int) {
   def lessThan(that: Rational): Boolean = {
     this.numer * that.denom < that.numer * this.denom
   }
+
+  @tailrec
+  private def gcd(a: Int, b: Int): Int = {
+    if (b == 0) a else gcd (b, a % b)
+  }
 }

src/test/scala/org/codecraftlabs/training/RationalSpec.scala

@@ -26,4 +26,11 @@ class RationalSpec extends AnyFlatSpec with Matchers {
     rational.numer shouldEqual 2
     rational.denom shouldEqual 1
   }
+
+  "Initial value 3/6" should "be converted to 1/2" in {
+    val rational = new Rational(3, 6)
+
+    rational.numer shouldEqual 1
+    rational.denom shouldEqual 2
+  }
 }