Scala Coding Editor for Technical Interviews

Running Scala 2.13 - Autocomplete is not available

You should define an object named Solution that extends App, like so:

object Solution extends App {
  for (i <- 0 until 5) println("Hello, world!")
}
Code language: Scala (scala)

Alternatively, you can forego using the App trait helper and define main yourself:

object Solution {
  def main(args: Array[String]) {
    println("Hello, world!")
  }
}
Code language: Scala (scala)

We include the Scala testing libraries ScalaCheck and ScalaTest for your convenience. Here’s a quick example of using ScalaTest driven by ScalaCheck generators:

import org.scalatest.prop.GeneratorDrivenPropertyChecks
import org.scalatest.{FreeSpec, Matchers}

class Testable extends FreeSpec
    with Matchers
    with GeneratorDrivenPropertyChecks {

  def f (x: Int) = Math abs x

  "f (x) should be >= 0" in forAll (
    (x: Int) => f (x) should be >= 0
  )

  "f (x) should be >= 0 (sometimes!)" in forAll (
    (x: Int) => whenever (x != Int.MinValue) (f (x) should be >= 0)
  )
}

object Solution extends App {
  new Testable().execute()
}
Code language: Scala (scala)

Here’s a quick rundown of the Scala libraries we have installed:

libraryDependencies ++= Seq (
  "com.chuusai"     %% "shapeless"                    % "2.3.2",
  "org.scalacheck"  %% "scalacheck"                   % "1.13.4",
  "org.scalactic"   %% "scalactic"                    % "3.0.1",
  "org.scalamock"   %% "scalamock-scalatest-support"  % "3.5.0",
  "org.scalatest"   %% "scalatest"                    % "3.0.1",
  "org.scalaz"      %% "scalaz-core"                  % "7.2.12",
  "org.typelevel"   %% "cats"                         % "0.9.0"
)
Code language: Scala (scala)

Additionally, these Java libraries are available. Simply import and fire away:

json-simple for parsing/encoding JSON.

The google code project page has some useful examples.

guava provides immutable collections and other handy utility classes.
junit, the gold standard for testing in Java, but quite usable in Scala as well.

  import org.junit.Test
  import org.junit.runner.JUnitCore
  import org.junit.Assert

  class TestClass {
    @Test def testNoop() {
      Assert.assertTrue(true)
    }
  }

  object Solution {
    def main(args: Array[String]) {
      JUnitCore.main("TestClass")
    }
  }
Code language: Scala (scala)

jMock, a library to assist with mocking in Java. The homepage has some useful examples, and can be adapted for Scala, too.

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