specJest

import { isArray, isBoolean, isString, isPlainObject, isUndefined, keys } from 'lodash';
import { gen } from 'jest-check';

const makeSpecable = (makeNotRequired, makeInvariant) => specable => {
    const notRequired = makeNotRequired(specable);
    notRequired.isRequired = specable;
    notRequired.invariant = func => makeInvariant(specable, func);
    return notRequired;
};

const specGen = makeSpecable(
    generator => gen.oneOf([gen.undefined, generator]),
    (generator, func) => gen.map(func, generator)
);

export const genSpec = {
    string: specGen(gen.asciiString),
    bool: specGen(gen.boolean),
    oneOf: list => specGen(gen.returnOneOf(list)),
    shape: shape => specGen(gen.object(shape)),
    arrayOf: itemSpec => specGen(gen.array(itemSpec))
};

const specJest = makeSpecable(
    check => actual => isUndefined(actual) || check(actual),
    (check, func) => actual => {
        expect(func(actual)).toEqual(actual);
        check(actual);
    }
);

export const jestSpec = {
    string: specJest(actual => expect(isString(actual)).toBe(true)),
    bool: specJest(actual => expect(isBoolean(actual)).toBe(true)),
    oneOf: list => specJest(actual => expect(list).toContainEqual(actual)),
    shape: shape => specJest(actual => {
        expect(isPlainObject(actual)).toBe(true);
        keys(shape).forEach(key => {
            shape[key](actual[key]);
        });
    }),
    arrayOf: itemSpec => specJest(actual => {
        expect(isArray(actual)).toBe(true);
        actual.forEach(item => itemSpec(item));
    })
};