Chapter02Spec.scala

import Chapter02._
import TestUtils.withOutput
import org.scalatest.{FlatSpec, Matchers}

class Chapter02Spec extends FlatSpec with Matchers {

  "signum" should "return -1 if n < 0, 1 if n > 0 and 0 if n = 0" in {
    //when & then
    signum(-2) shouldBe -1
    signum(-1) shouldBe -1
    signum(0) shouldBe 0
    signum(1) shouldBe 1
    signum(2) shouldBe 1
  }

  "task2" should "return Unit value" in {
    //when & then
    task2() shouldBe {}
  }

  "task3" should "return Unit as result of x = y = 1 expression" in {
    //when & then
    task3() shouldBe {}
  }

  "task4" should "implement simple Java for loop" in {
    //when
    val scalaOut = withOutput {
      task4()
    }

    //then
    scalaOut shouldBe withOutput {
      Chapter02Task4.javaForLoop()
    }
  }

  "countdown" should "print the numbers from n to 0" in {
    //when & then
    withOutput(countdown(3)) shouldBe """3
                                        |2
                                        |1
                                        |0
                                        |""".stripMargin

    withOutput(countdown(0)) shouldBe """0
                                        |""".stripMargin

    withOutput(countdown(-1)) shouldBe ""
  }

  "productLoop" should "compute product of Unicode codes letters in string using loop" in {
    //when & then
    productLoop("Hello") shouldBe 825152896
  }

  "productNoLoop" should "compute product of Unicode codes letters in string without loop" in {
    //when & then
    productNoLoop("Hello") shouldBe 825152896
  }

  "product" should "compute product of Unicode codes letters in string" in {
    //when & then
    product("Hello") shouldBe 825152896
  }

  "productRecursive" should "compute product of Unicode codes letters in string recursively" in {
    //when & then
    productRecursive("Hello") shouldBe 825152896
  }

  "pow" should "compute x^n recursively" in {
    //when & then
    pow(-2, 0) shouldBe 1.0
    pow(1, 0) shouldBe 1.0
    pow(0, 0) shouldBe 1.0
    pow(1, 0) shouldBe 1.0
    pow(2, 0) shouldBe 1.0
    pow(1, 2) shouldBe 1.0
    pow(1, 3) shouldBe 1.0
    pow(2, -2) shouldBe 0.25
    pow(2, -1) shouldBe 0.5
    pow(2, 0) shouldBe 1.0
    pow(2, 1) shouldBe 2.0
    pow(2, 2) shouldBe 4.0
    pow(2, 3) shouldBe 8.0
    pow(2, 4) shouldBe 16.0
    pow(3, 0) shouldBe 1.0
    pow(3, 1) shouldBe 3.0
    pow(3, 2) shouldBe 9.0
    pow(5, 0) shouldBe 1.0
    pow(5, 1) shouldBe 5.0
    pow(5, 2) shouldBe 25.0
    pow(5, 3) shouldBe 125.0
  }
}