Testing Basics

Expected vs Actual

Compare an actual value against the expected one.

expect-actual A basic test compares an actual result with the expected value and reports a pass or fail status. No test framework is needed for the idea.

Expected vs Actual

actual
ExpectActual.scala
Replay: real traced execution (multi-file project)
object Main {
  def main(args: Array[String]): Unit = {
    val actual = 4
    val expected = 4
    val pass = actual == expected
    val status = if (pass) "PASS" else "FAIL"

    println("expected=" + expected)
    println("actual=" + actual)
    println("status=" + status)
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val actual = 3
    val expected = 4
    val pass = actual == expected
    val status = if (pass) "PASS" else "FAIL"

    println("expected=" + expected)
    println("actual=" + actual)
    println("status=" + status)
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val actual = 5
    val expected = 4
    val pass = actual == expected
    val status = if (pass) "PASS" else "FAIL"

    println("expected=" + expected)
    println("actual=" + actual)
    println("status=" + status)
  }
}

  1. actual ← 4, expected ← 4, pass ← true, status ← PASS

    1object Main {2  def main(args: Array[String]): Unit = {3    val actual→ 4 = 4 //@actual=5, 34    val expected→ 4 = 45    val pass→ true = actual4 == expected46    val status→ PASS = if (passtrue) "PASS" else "FAIL"78    println("expected=" + expected4)9    println("actual=" + actual4)10    println("status=" + statusPASS)11  }12}
    outputexpected=4
actual=4
status=PASS

  1. actual ← 3, expected ← 4, pass ← false, status ← FAIL

    1object Main {2  def main(args: Array[String]): Unit = {3    val actual→ 3 = 34    val expected→ 4 = 45    val pass→ false = actual3 == expected46    val status→ FAIL = if (passfalse) "PASS" else "FAIL"78    println("expected=" + expected4)9    println("actual=" + actual3)10    println("status=" + statusFAIL)11  }12}
    outputexpected=4
actual=3
status=FAIL

  1. actual ← 5, expected ← 4, pass ← false, status ← FAIL

    1object Main {2  def main(args: Array[String]): Unit = {3    val actual→ 5 = 54    val expected→ 4 = 45    val pass→ false = actual5 == expected46    val status→ FAIL = if (passfalse) "PASS" else "FAIL"78    println("expected=" + expected4)9    println("actual=" + actual5)10    println("status=" + statusFAIL)11  }12}
    outputexpected=4
actual=5
status=FAIL