Convert sub to TypeScript (date-fns#2594)

Co-authored-by: Tan75 <[email protected]>
Co-authored-by: Sasha Koss <[email protected]>

src/sub/index.js → src/sub/index.ts

@@ -1,6 +1,6 @@
 import subDays from '../subDays/index'
 import subMonths from '../subMonths/index'
-import toDate from '../toDate/index'
+import { Duration } from '../types'
 import requiredArgs from '../_lib/requiredArgs/index'
 import toInteger from '../_lib/toInteger/index'
 
@@ -43,7 +43,10 @@ import toInteger from '../_lib/toInteger/index'
  * })
  * //=> Mon Sep 1 2014 10:19:50
  */
-export default function sub(dirtyDate, duration) {
+export default function sub(
+  date: Date | number,
+  duration: Duration
+): Date {
   requiredArgs(2, arguments)
 
   if (!duration || typeof duration !== 'object') return new Date(NaN)
@@ -57,7 +60,7 @@ export default function sub(dirtyDate, duration) {
   const seconds = duration.seconds ? toInteger(duration.seconds) : 0
 
   // Subtract years and months
-  const dateWithoutMonths = subMonths(toDate(dirtyDate), months + years * 12)
+  const dateWithoutMonths = subMonths(date, months + years * 12)
 
   // Subtract weeks and days
   const dateWithoutDays = subDays(dateWithoutMonths, days + weeks * 7)

src/sub/test.js → src/sub/test.ts

@@ -1,4 +1,3 @@
-// @flow
 /* eslint-env mocha */
 
 import assert from 'power-assert'
@@ -62,8 +61,11 @@ describe('sub', () => {
   })
 
   it('implicitly converts number arguments', () => {
-    // $ExpectedMistake
-    const result = sub(new Date(2014, 8 /* Sep */, 1, 14), { hours: '4.2' })
+    const result = sub(
+      new Date(2014, 8 /* Sep */, 1, 14),
+      // @ts-expect-error
+      { hours: '4.2' }
+    )
     assert.deepEqual(result, new Date(2014, 8 /* Sep */, 1, 10))
   })
 
@@ -92,13 +94,16 @@ describe('sub', () => {
 
   it('returns `Invalid Date` if the given date is invalid', () => {
     const result = sub(new Date(NaN), { hours: 5 })
-    assert(result instanceof Date && isNaN(result))
+    assert(result instanceof Date && isNaN(result.getTime()))
   })
 
   it('throws RangeError exception if passed Number as duration', () => {
-    // $ExpectedMistake
-    const result = sub(new Date(2014, 8, 1), 'wut')
-    assert(result instanceof Date && isNaN(result))
+    const result = sub(
+      new Date(2014, 8, 1),
+      // @ts-expect-error
+      'wut'
+    )
+    assert(result instanceof Date && isNaN(result.getTime()))
   })
 
   it('throws TypeError exception if passed less than 2 arguments', () => {