export class AssertionError extends Error {
    constructor(message) {
        super(message)
    }
}

export const assert = (value, message = `assertion error: ${value} is not true`) => {
    assertEq(value, true, message)
}

export const assertEq = (a, b, message = `assertion error: ${a} !== ${b}`) => {
    if (a === b) {
        return
    }
    else if (Array.isArray(b) && a.length === b.length) {
        b.forEach((n, i) => assertEq(a[i], n))
        return
    } else {
        throw new AssertionError(message)
    }
}

export const assertCallback = () => {
    let result = false
    setTimeout(() => assert(result), 0)
    return () => result = true
}

export const it = (description, test) => {
    return () => {
        try {
            test()

            return {
                success: true,
                description,
                error: undefined
            }
        } catch (error) {
            return {
                success: false,
                description,
                error
            }
        }
    }
}