adds more tests for period predictions, moves getcycleslength into cycle module

lib/cycle-length.js

@@ -1,6 +1,4 @@
 import assert from 'assert'
-import { LocalDate, ChronoUnit } from 'js-joda'
-import cycleModule from '../lib/cycle'
 
 export function getCycleLengthStats(cycleLengths) {
   throwIfArgsAreNotInRequiredFormat(cycleLengths)
@@ -48,14 +46,4 @@ function throwIfArgsAreNotInRequiredFormat(cycleLengths) {
     assert.equal(typeof cycleLength, 'number', 'Elements in the array should be of type number.')
     assert.ok(!isNaN(cycleLength), 'Elements of array should not be NaN.')
   })
-}
-
-export function getCycleLength(cycleStartDates) {
-  const cycleLengths = []
-  for (let i = 0; i < cycleStartDates.length - 1; i++) {
-    const nextCycleStart = LocalDate.parse(cycleStartDates[i])
-    const cycleStart = LocalDate.parse(cycleStartDates[i + 1])
-    cycleLengths.push(cycleStart.until(nextCycleStart, ChronoUnit.DAYS))
-  }
-  return cycleLengths
 }