Add protein-translation exercise (#356)

* Add protein-translation exercise

* Fix duplicate assertions in test suite

Author: ricemery

config.json

@@ -236,6 +236,15 @@
             "Structural equality"
          ]
       },
+      {
+         "slug":"protein-translation",
+         "difficulty":3,
+         "topics":[
+            "Strings",
+            "Transforming",
+            "Sequences"
+         ]
+      },
       {
          "slug":"matrix",
          "difficulty":4,

exercises/protein-translation/build.sbt

@@ -0,0 +1,3 @@
+scalaVersion := "2.12.1"
+
+libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.1" % "test"

exercises/protein-translation/example.scala

@@ -0,0 +1,41 @@
+import scala.annotation.tailrec
+
+object ProteinTranslation {
+
+  private val translations = Map(
+    "AUG" -> "Methionine",
+    "UUU" -> "Phenylalanine",
+    "UUC" -> "Phenylalanine",
+    "UUA" -> "Leucine",
+    "UUG" -> "Leucine",
+    "UCU" -> "Serine",
+    "UCC" -> "Serine",
+    "UCA" -> "Serine",
+    "UCG" -> "Serine",
+    "UAU" -> "Tyrosine",
+    "UAC" -> "Tyrosine",
+    "UGU" -> "Cysteine",
+    "UGC" -> "Cysteine",
+    "UGG" -> "Tryptophan",
+    "UAA" -> "STOP",
+    "UAG" -> "STOP",
+    "UGA" -> "STOP")
+
+  /**
+    * Note that this solution ignores invalid Codons.
+    */
+  def translate(input: String): Seq[String] = {
+    @tailrec
+    def translate_internal(acc: Seq[String], strs: Seq[String]): Seq[String] = {
+      strs match {
+        case x::xs => translations get x match {
+          case Some(codon) => if ("STOP".equals(codon)) acc.reverse else translate_internal(codon +: acc, xs)
+          case _ => translate_internal(acc, xs)
+        }
+        case _ => acc.reverse
+      }
+    }
+
+    translate_internal(Seq(), input.grouped(3).toList)
+  }
+}

exercises/protein-translation/src/main/scala/.keep

@@ -0,0 +1,59 @@
+import org.scalatest.{FunSuite, Matchers}
+
+class ProteinTranslationTest extends FunSuite with Matchers {
+  test("Identifies methionine codon") {
+    ProteinTranslation.translate("AUG") should be(Seq("Methionine"))
+  }
+
+  test("Identifies phenylalanine codons") {
+    pending
+    ProteinTranslation.translate("UUU") should be(Seq("Phenylalanine"))
+    ProteinTranslation.translate("UUC") should be(Seq("Phenylalanine"))
+  }
+
+  test("Identifies leucine codons") {
+    pending
+    ProteinTranslation.translate("UUA") should be(Seq("Leucine"))
+    ProteinTranslation.translate("UUG") should be(Seq("Leucine"))
+  }
+
+  test("Identifies serine codons") {
+    pending
+    ProteinTranslation.translate("UCU") should be(Seq("Serine"))
+    ProteinTranslation.translate("UCC") should be(Seq("Serine"))
+    ProteinTranslation.translate("UCA") should be(Seq("Serine"))
+    ProteinTranslation.translate("UCG") should be(Seq("Serine"))
+  }
+
+  test("Identifies tyrosine codons") {
+    pending
+    ProteinTranslation.translate("UAU") should be(Seq("Tyrosine"))
+    ProteinTranslation.translate("UAC") should be(Seq("Tyrosine"))
+  }
+
+  test("Identifies cysteine codons") {
+    pending
+    ProteinTranslation.translate("UGU") should be(Seq("Cysteine"))
+    ProteinTranslation.translate("UGC") should be(Seq("Cysteine"))
+  }
+
+  test("Identifies tryptophan codons") {
+    pending
+    ProteinTranslation.translate("UGG") should be(Seq("Tryptophan"))
+  }
+
+  test("Translate RNA strand into correct protein") {
+    pending
+    ProteinTranslation.translate("AUGUUUUGG") should be(Seq("Methionine", "Phenylalanine", "Tryptophan"))
+  }
+
+  test("Stops translation if stop codon is present") {
+    pending
+    ProteinTranslation.translate("AUGUUUUAA") should be(Seq("Methionine", "Phenylalanine"))
+  }
+
+  test("Stops translation of longest strand") {
+    pending
+    ProteinTranslation.translate("UGGUGUUAUUAAUGGUUU") should be(Seq("Tryptophan", "Cysteine", "Tyrosine"))
+  }
+}