ScalaでC#っぽい Date ⇔ StringとかDate同士の大小比較とかするためのtrait

DateUtil.scala

package util

import java.util.Date
import java.text.SimpleDateFormat

object DateUtil {
  implicit class StringToDate(self: String) {
    /**
     * フォーマット指定された形式でDate型に変換する
     *
     * @param format 変換フォーマット
     * @return
     */
    def toDate(format: String): Date = {
      val sdf = new SimpleDateFormat(format)
      sdf.parse(self)
    }
  }

  implicit class DateToString(self: Date) {
    /**
     * フォーマット指定された形式でString型に変換する
     *
     * @param format
     */
    def toString(format: String): String = {
      val sdf = new SimpleDateFormat(format)
      sdf.format(self)
    }
  }

  implicit class DateCompare(self: Date) {
    def >(that: Date): Boolean = {
      self.after(that)
    }
    def >=(that: Date): Boolean = {
      self.after(that) || self == that
    }
    def <(that: Date): Boolean = {
      self.before(that)
    }
    def <=(that: Date): Boolean = {
      self.before(that) || self == that
    }
  }
}

DateUtilSpec.scala

package util

import java.text.SimpleDateFormat
import org.specs2.mutable.Specification
import util.DateUtil._

class DateUtilSpec extends Specification {

  val sdf = new SimpleDateFormat("yyyyMMdd")
  val apr_1st = sdf.parse("20130401")
  val apr_2nd = sdf.parse("20130402")
  val apr_3rd = sdf.parse("20130403")

  "DateUtil" should {
    "toDate" in {
      "20130401".toDate("yyyyMMdd") must beEqualTo(sdf.parse("20130401"))
    }
    "toDate parse Error" in {
      "hoge".toDate("yyyyMMdd") must throwA[java.text.ParseException]
    }
    "toDate format Error" in {
      "20130401".toDate("hoge") must throwA[IllegalArgumentException]
    }

    "toString" in {
      apr_1st.toString("yyyyMMdd") must beEqualTo("20130401")
    }
    "toString format error" in {
      apr_1st.toString("hoge") must throwA[IllegalArgumentException]
    }

    "Compare > " in {
      (apr_1st > apr_2nd) must beEqualTo(false)
      (apr_1st > apr_1st) must beEqualTo(false)
      (apr_2nd > apr_1st) must beEqualTo(true)
    }

    "Compare >= " in {
      (apr_1st >= apr_2nd) must beEqualTo(false)
      (apr_2nd >= apr_2nd) must beEqualTo(true)
      (apr_2nd >= apr_1st) must beEqualTo(true)
    }

    "Compare < " in {
      (apr_2nd < apr_1st) must beEqualTo(false)
      (apr_2nd < apr_2nd) must beEqualTo(false)
      (apr_1st < apr_2nd) must beEqualTo(true)
    }
    "Compare <= " in {
      (apr_2nd <= apr_1st) must beEqualTo(false)
      (apr_1st <= apr_1st) must beEqualTo(true)
      (apr_1st <= apr_2nd) must beEqualTo(true)
    }

    "Compare Range 'true' " in {
      apr_1st < apr_2nd &&
        apr_2nd < apr_3rd must beEqualTo(true)

      apr_1st <= apr_2nd &&
        apr_2nd <= apr_3rd must beEqualTo(true)

      apr_3rd > apr_2nd &&
        apr_2nd > apr_1st must beEqualTo(true)

      apr_3rd >= apr_2nd &&
        apr_2nd >= apr_1st must beEqualTo(true)
    }
  }

}