areIntervalsOverlapping works inconsistently with zero-length intervals.

[chatoo2412]

The problem

areIntervalsOverlapping works inconsistently with zero-length intervals.
It returns false as expected, if the interval is very left or very right of another one.
The problem is when the interval is middle of another one, which returns true.

Demo

import { areIntervalsOverlapping } from 'date-fns';

console.log(areIntervalsOverlapping({ start: 0, end: 10 }, { start: 1, end: 1 })); // true
console.log(areIntervalsOverlapping({ start: 0, end: 10 }, { start: 0, end: 0 })); // false
console.log(areIntervalsOverlapping({ start: 0, end: 10 }, { start: 10, end: 10 })); // false

Expected Behavior

all cases return false

Debug Information

• date-fns version: v3.6.0

[IgnusG]

I think this is expected. Your interval from 1 to 1 is inside of the other interval from 0 to 10 so areIntervalsOverlapping correctly returns true. The edges only return false since the third option (inclusive is not turned on). If you turn it on where it considers intervals adjacent to each other as overlapping it will return correctly true:

console.log(areIntervalsOverlapping({ start: 0, end: 10 }, { start: 10, end: 10 })); // false - intervals not overlapping
console.log(areIntervalsOverlapping({ start: 0, end: 10 }, { start: 10, end: 10 }, { inclusive: true })); // true - intervals not overlapping but adjacent to each other

[chatoo2412]

I got it, but still hard to understand intuitively. :(
Thanks.