Break up large group of .combine() tests

src/main/scala/catslib/Semigroup.scala

@@ -45,25 +45,27 @@ object SemigroupSection
   * guess how it works in the following examples:
   *
   */
  def semigroupCombine(
      res0: Int,
      res1: List[Int],
      res2: Option[Int],
      res3: Option[Int],
      res4: Int) = {
  def semigroupCombine(res0: Int, res1: List[Int], res2: Option[Int], res3: Option[Int]) = {
    import cats.implicits._

    Semigroup[Int].combine(1, 2) should be(res0)
    Semigroup[List[Int]].combine(List(1, 2, 3), List(4, 5, 6)) should be(res1)
    Semigroup[Option[Int]].combine(Option(1), Option(2)) should be(res2)
    Semigroup[Option[Int]].combine(Option(1), None) should be(res3)
  }

  /** And now try a slightly more complex combination:
   */
  def semigroupCombineComplex(res0: Int) = {
    import cats.implicits._

    Semigroup[Int ⇒ Int]
      .combine({ (x: Int) ⇒
        x + 1
      }, { (x: Int) ⇒
        x * 10
      })
      .apply(6) should be(res4)
      .apply(6) should be(res0)
  }

  /** Many of these types have methods defined directly on them,