Core scala refactor (#5654)

* encoding

* Converting synchronous and asynchronous API to observables

* Adding different ways of converting sync/async APIs to observalbles.

* Replace anonymous class with lambda

* update based on comment from Grzegorz Piwowarek

* Refactor core-scala examples

* Cleanup

core-scala/src/main/scala/com/baeldung/scala/Employee.scala

@@ -22,6 +22,6 @@ class Employee(val name : String,
  * A Trait which will make the toString return upper case value.
  */
 trait UpperCasePrinter {
-  override def toString = super.toString toUpperCase
+  override def toString: String = super.toString toUpperCase
 }
 

core-scala/src/main/scala/com/baeldung/scala/HigherOrderFunctions.scala

@@ -11,7 +11,7 @@ object HigherOrderFunctions {
   def mapReduce(r : (Int, Int) => Int,
                 i : Int,
                 m : Int => Int,
-                a : Int, b : Int) = {
+                a : Int, b : Int): Int = {
     def iter(a : Int, result : Int) : Int = {
       if (a > b) result
       else iter(a + 1, r(m(a), result))

core-scala/src/main/scala/com/baeldung/scala/Utils.scala

@@ -7,9 +7,9 @@ package com.baeldung.scala
  *
  */
 object Utils {
-  def average(x : Double, y : Double) = (x + y) / 2
+  def average(x : Double, y : Double): Double = (x + y) / 2
 
-  def randomLessThan(d : Double) = {
+  def randomLessThan(d : Double): Double = {
     var random = 0d
     do {
       random = Math.random()

core-scala/src/test/scala/com/baeldung/scala/ControlStructuresDemoUnitTest.scala

@@ -1,32 +1,32 @@
 package com.baeldung.scala
 
 import com.baeldung.scala.ControlStructuresDemo._
-import org.junit.Test
 import org.junit.Assert.assertEquals
+import org.junit.Test
 
 class ControlStructuresDemoUnitTest {
   @Test
-  def givenTwoIntegers_whenGcdCalled_thenCorrectValueReturned = {
+  def givenTwoIntegers_whenGcdCalled_thenCorrectValueReturned() = {
     assertEquals(3, gcd(15, 27))
   }
 
   @Test
-  def givenTwoIntegers_whenGcdIterCalled_thenCorrectValueReturned = {
+  def givenTwoIntegers_whenGcdIterCalled_thenCorrectValueReturned() = {
     assertEquals(3, gcdIter(15, 27))
   }
 
   @Test
-  def givenTwoIntegers_whenRangeSumcalled_thenCorrectValueReturned = {
+  def givenTwoIntegers_whenRangeSumcalled_thenCorrectValueReturned() = {
     assertEquals(55, rangeSum(1, 10))
   }
 
   @Test
-  def givenPositiveInteger_whenFactorialInvoked_thenCorrectValueReturned = {
+  def givenPositiveInteger_whenFactorialInvoked_thenCorrectValueReturned() = {
     assertEquals(720, factorial(6))
   }
 
   @Test
-  def whenFactorialOf0Invoked_then1Returned = {
+  def whenFactorialOf0Invoked_then1Returned() = {
     assertEquals(1, factorial(0))
   }
 

core-scala/src/test/scala/com/baeldung/scala/EmployeeUnitTest.scala

@@ -6,20 +6,20 @@ import org.junit.Test
 class EmployeeUnitTest {
 
   @Test
-  def whenEmployeeSalaryIncremented_thenCorrectSalary = {
+  def whenEmployeeSalaryIncremented_thenCorrectSalary() = {
     val employee = new Employee("John Doe", 1000)
     employee.incrementSalary()
     assertEquals(1020, employee.salary)
   }
 
   @Test
-  def givenEmployee_whenToStringCalled_thenCorrectStringReturned = {
+  def givenEmployee_whenToStringCalled_thenCorrectStringReturned() = {
     val employee = new Employee("John Doe", 1000)
     assertEquals("Employee(name=John Doe, salary=1000)", employee.toString)
   }
 
   @Test
-  def givenEmployeeWithTrait_whenToStringCalled_thenCorrectStringReturned = {
+  def givenEmployeeWithTrait_whenToStringCalled_thenCorrectStringReturned() = {
     val employee =
       new Employee("John Doe", 1000) with UpperCasePrinter
     assertEquals("EMPLOYEE(NAME=JOHN DOE, SALARY=1000)", employee.toString)

core-scala/src/test/scala/com/baeldung/scala/HigherOrderFunctionsUnitTest.scala

@@ -1,14 +1,13 @@
 package com.baeldung.scala
 
+import com.baeldung.scala.HigherOrderFunctions.mapReduce
 import org.junit.Assert.assertEquals
 import org.junit.Test
 
-import HigherOrderFunctions.mapReduce
-
 class HigherOrderFunctionsUnitTest {
 
   @Test
-  def whenCalledWithSumAndSquareFunctions_thenCorrectValueReturned = {
+  def whenCalledWithSumAndSquareFunctions_thenCorrectValueReturned() = {
     def square(x : Int) = x * x
 
     def sum(x : Int, y : Int) = x + y
@@ -20,7 +19,7 @@ class HigherOrderFunctionsUnitTest {
   }
 
   @Test
-  def whenComputingSumOfSquaresWithAnonymousFunctions_thenCorrectValueReturned = {
+  def whenComputingSumOfSquaresWithAnonymousFunctions_thenCorrectValueReturned() = {
     def sumSquares(a : Int, b : Int) =
       mapReduce((x, y) => x + y, 0, x => x * x, a, b)
 
@@ -28,7 +27,7 @@ class HigherOrderFunctionsUnitTest {
   }
 
   @Test
-  def givenCurriedFunctions_whenInvoked_thenCorrectValueReturned = {
+  def givenCurriedFunctions_whenInvoked_thenCorrectValueReturned() = {
     // a curried function
     def sum(f : Int => Int)(a : Int,
                             b : Int) : Int =

core-scala/src/test/scala/com/baeldung/scala/IntSetUnitTest.scala

@@ -1,14 +1,12 @@
 package com.baeldung.scala
 
-import scala.Range
-
 import org.junit.Assert.assertFalse
 import org.junit.Test
 
 class IntSetUnitTest {
 
   @Test
-  def givenSetof1To10_whenContains11Called_thenFalse = {
+  def givenSetof1To10_whenContains11Called_thenFalse() = {
 
     // Set up a set containing integers 1 to 10.
     val set1To10 =

core-scala/src/test/scala/com/baeldung/scala/UtilsUnitTest.scala

@@ -1,34 +1,29 @@
 package com.baeldung.scala
 
-import org.junit.Assert.assertEquals
+import com.baeldung.scala.Utils.{average, fibonacci, power, randomLessThan}
-import org.junit.Assert.assertTrue
+import org.junit.Assert.{assertEquals, assertTrue}
 import org.junit.Test
 
-import Utils.average
-import Utils.fibonacci
-import Utils.power
-import Utils.randomLessThan
-
 class UtilsUnitTest {
 
   @Test
-  def whenAverageCalled_thenCorrectValueReturned() = {
+  def whenAverageCalled_thenCorrectValueReturned(): Unit = {
     assertEquals(15.0, average(10, 20), 1e-5)
   }
 
   @Test
-  def whenRandomLessThanInvokedWithANumber_thenARandomLessThanItReturned = {
+  def whenRandomLessThanInvokedWithANumber_thenARandomLessThanItReturned: Unit = {
     val d = 0.1
     assertTrue(randomLessThan(d) < d)
   }
 
   @Test
-  def whenPowerInvokedWith2And3_then8Returned = {
+  def whenPowerInvokedWith2And3_then8Returned: Unit = {
     assertEquals(8, power(2, 3))
   }
 
   @Test
-  def whenFibonacciCalled_thenCorrectValueReturned = {
+  def whenFibonacciCalled_thenCorrectValueReturned: Unit = {
     assertEquals(1, fibonacci(0))
     assertEquals(1, fibonacci(1))
     assertEquals(fibonacci(6),