Add DateRange.prepend (opposite direction of extend) (#1748)

* create new function to extend daterange in past time * unit tests for preprend/extend/embiggen
twitter · Oct 22, 2017 · e40bf1b · e40bf1b
1 parent d53d06f
commit e40bf1b
Show file tree

Hide file tree

Showing 2 changed files with 13 additions and 0 deletions.
diff --git a/scalding-date/src/main/scala/com/twitter/scalding/DateRange.scala b/scalding-date/src/main/scala/com/twitter/scalding/DateRange.scala
@@ -93,6 +93,12 @@ case class DateRange(val start: RichDate, val end: RichDate) {
    */
   def extend(delta: Duration) = DateRange(start, end + delta)
 
+  /**
+   * Extend the length by moving the start.
+   * Turns out, we can start the party early.
+   */
+  def prepend(delta: Duration) = DateRange(start - delta, end)
+
   def contains(point: RichDate) = (start <= point) && (point <= end)
   /**
    * Is the given Date range a (non-strict) subset of the given range

diff --git a/scalding-date/src/test/scala/com/twitter/scalding/DateTest.scala b/scalding-date/src/test/scala/com/twitter/scalding/DateTest.scala
@@ -212,6 +212,13 @@ class DateTest extends WordSpec {
     "reject an end that is before its start" in {
       intercept[IllegalArgumentException] { DateRange("2010-10-02", "2010-10-01") }
     }
+    "correctly add time in either or both directions" in {
+      assert(DateRange("2010-10-01", "2010-10-02").extend(Days(3)).each(Days(1)).size === 5)
+      assert(DateRange("2010-10-01", "2010-10-02").prepend(Days(3)).each(Days(1)).size === 5)
+      assert(DateRange("2010-10-01", "2010-10-02").embiggen(Days(3)).each(Days(1)).size === 8)
+      assert(DateRange("2010-10-01", "2010-10-10").extend(Days(1)).prepend(Days(1)) ==
+        DateRange("2010-10-01", "2010-10-10").embiggen(Days(1)))
+    }
   }
   "Time units" should {
     def isSame(d1: Duration, d2: Duration) = {