feat: localDate would Math.floor fractional input on .plus

src/datetime/localDate.test.ts

@@ -390,3 +390,17 @@ test('todayString tz', () => {
   console.log(localDate.todayString())
   console.log(new Date().toString())
 })
+
+test('fractional unit input', () => {
+  const ld = localDate('1984-06-21')
+  expect(ld.plus(0.4, 'day').toISODate()).toBe('1984-06-21')
+  expect(ld.plus(0.5, 'day').toISODate()).toBe('1984-06-21')
+  expect(ld.plus(0.9, 'day').toISODate()).toBe('1984-06-21')
+  expect(ld.plus(1.1, 'day').toISODate()).toBe('1984-06-22')
+  expect(ld.minus(0.4, 'day').toISODate()).toBe('1984-06-20')
+  expect(ld.minus(0.5, 'day').toISODate()).toBe('1984-06-20')
+  expect(ld.minus(0.9, 'day').toISODate()).toBe('1984-06-20')
+  expect(ld.minus(1.1, 'day').toISODate()).toBe('1984-06-19')
+
+  expect(localDate('1984-06-21.5').toISODate()).toBe('1984-06-21')
+})

src/datetime/localDate.ts

@@ -287,6 +287,7 @@ export class LocalDate {
   }
 
   plus(num: number, unit: LocalDateUnit, mutate = false): LocalDate {
+    num = Math.floor(num) // if a fractional number like 0.5 is passed - it will be floored, as LocalDate only deals with "whole days" as minimal unit
     let { day, month, year } = this
 
     if (unit === 'week') {

src/datetime/localTime.test.ts

@@ -584,3 +584,33 @@ test('parsing date string in negative timezone bug', () => {
   expect(lt.toISODate()).toBe(s)
   expect(lt.toPretty()).toBe('2023-03-03 00:00:00')
 })
+
+test('fractional unit input', () => {
+  const lt = localTime('1984-06-21')
+  expect(lt.toString()).toBe('1984-06-21T00:00:00')
+
+  // Comparing only IsoDate part (no time component)
+  expect(lt.plus(0.4, 'day').toISODate()).toBe('1984-06-21')
+  expect(lt.plus(0.5, 'day').toISODate()).toBe('1984-06-21')
+  expect(lt.plus(0.9, 'day').toISODate()).toBe('1984-06-21')
+  expect(lt.plus(1.1, 'day').toISODate()).toBe('1984-06-22')
+  expect(lt.minus(0.4, 'day').toISODate()).toBe('1984-06-20')
+  expect(lt.minus(0.5, 'day').toISODate()).toBe('1984-06-20')
+  expect(lt.minus(0.9, 'day').toISODate()).toBe('1984-06-20')
+  expect(lt.minus(1.1, 'day').toISODate()).toBe('1984-06-19')
+
+  // Comparing full date+time component.
+  // LocalTime does NOT support fractional input, so it should be coerced (Math.floored) to Integer
+  expect(lt.plus(0.4, 'day').toString()).toBe('1984-06-21T00:00:00')
+  expect(lt.plus(0.5, 'day').toString()).toBe('1984-06-21T00:00:00')
+  expect(lt.plus(0.9, 'day').toString()).toBe('1984-06-21T00:00:00')
+  expect(lt.plus(1.1, 'day').toString()).toBe('1984-06-22T00:00:00')
+  expect(lt.minus(0.4, 'day').toString()).toBe('1984-06-20T00:00:00')
+  expect(lt.minus(0.5, 'day').toString()).toBe('1984-06-20T00:00:00')
+  expect(lt.minus(0.9, 'day').toString()).toBe('1984-06-20T00:00:00')
+  expect(lt.minus(1.1, 'day').toString()).toBe('1984-06-19T00:00:00')
+
+  expect(() => localTime('1984-06-21.5')).toThrowErrorMatchingInlineSnapshot(
+    `"Cannot parse "1984-06-21.5" into LocalTime"`,
+  )
+})