Add diff in days

package.json

@@ -1,6 +1,6 @@
 {
   "name": "valid-objects-ts",
-  "version": "1.0.5",
+  "version": "1.0.6",
   "main": ".dist/index.js",
   "types": ".dist/index.d.ts",
   "repository": "[email protected]:Travelport-Czech/valid-objects-ts.git",

src/validObjects/ValidDate.test.ts

@@ -17,4 +17,20 @@ describe('ValidDate', () => {
 
     expect(JSON.stringify(data)).to.eq('{"date":"2018-12-24"}')
   })
+
+  it('Diff in days', () => {
+    const date = new ValidDate('2018-12-24')
+
+    const date1 = new ValidDate('2018-12-24')
+    expect(date.diffInDays(date1)).to.equal(0)
+
+    const date2 = new ValidDate('2018-12-23')
+    expect(date.diffInDays(date2)).to.equal(1)
+
+    const date3 = new ValidDate('2018-12-25')
+    expect(date.diffInDays(date3)).to.equal(-1)
+
+    const date4 = new ValidDate('2017-12-24')
+    expect(date.diffInDays(date4)).to.equal(365)
+  })
 })

src/validObjects/ValidDate.ts

@@ -69,6 +69,10 @@ export class ValidDate {
     )
   }
 
+  public readonly diffInDays = (date: ValidDate): number => {
+    return this.moment().diff(date.moment(), 'days')
+  }
+
   public readonly formatToSystem = (): string => {
     return this.moment().format(formatSystemDate)
   }