import { it, assertEq } from 'folktest'
import { Ok, Err } from '../../src/result.js'
import { prove } from './monad.js'

const id = x => () => x
export const Tests = [
    it('should pass monadic laws', () => {
        prove(
            Ok,
            Ok(1),
            1,
            x => Ok(x + 1),
            x => Ok(x * 2)
        )

        const e = new Error()
        prove(
            Err,
            Err(e),
            e,
            x => Err(new Error()),
            x => Err(new Error())
        )
    }),

    it('should not bind err', () => {
        const e = new Error()
        const result = Ok(1)
            .bind(id(Err(e)))
            .bind(id(Ok(1)))
            .map(x => x + 1)

        assertEq(result, Err(e))
    }),
]