Moves out the test for getPReviousCycle method of cycle module

test/get-previous-cycle.spec.js

@@ -0,0 +1,72 @@
+import chai from 'chai'
+import dirtyChai from 'dirty-chai'
+import cycleModule from '../lib/cycle'
+
+const { expect } = chai
+chai.use(dirtyChai)
+
+const mayCycle = [
+  { date: '2018-05-05' },
+  { date: '2018-05-04' },
+  { date: '2018-05-03' },
+]
+
+const cycleDaysSortedByDate = [
+  { date: '2018-07-05' },
+  { date: '2018-06-05' },
+  ...mayCycle,
+  { date: '2018-04-05' },
+  { date: '2018-04-04' },
+  { date: '2018-04-03' },
+  { date: '2018-04-02' },
+]
+
+const cycleStartsSortedByDate = [
+  { date: '2018-07-05' },
+  { date: '2018-06-05' },
+  { date: '2018-05-03' },
+  { date: '2018-04-02' },
+]
+
+describe('getPreviousCycle', () => {
+  it('gets previous cycle', () => {
+
+    const { getPreviousCycle } = cycleModule({
+      cycleDaysSortedByDate,
+      cycleStartsSortedByDate,
+    })
+
+    expect(getPreviousCycle('2018-06-08')).to.eql(mayCycle)
+  })
+
+  it('returns null when target day is not in a cyle', () => {
+
+    const { getPreviousCycle } = cycleModule({
+      cycleDaysSortedByDate,
+      cycleStartsSortedByDate: [],
+    })
+
+    expect(getPreviousCycle('2018-06-08')).to.eql(null)
+  })
+
+  it('returns null when there is no previous cycle', () => {
+
+    const { getPreviousCycle } = cycleModule({
+      cycleDaysSortedByDate,
+      cycleStartsSortedByDate,
+    })
+
+    expect(getPreviousCycle('2018-04-18')).to.eql(null)
+  })
+
+  it('returns null when the previous cycle > maxcyclelength', () => {
+
+    const { getPreviousCycle } = cycleModule({
+      cycleDaysSortedByDate,
+      cycleStartsSortedByDate,
+      maxCycleLength: 2,
+    })
+
+    expect(getPreviousCycle('2018-06-08')).to.eql(null)
+  })
+})