ts-prime/dist/es/first.test.js

A utility library for JavaScript and Typescript.

import { first } from './first';
import { pipe } from './pipe';
import { createCounter } from './_counter';
import { filter } from './filter';
function defaultTo(d) {
    return function (v) {
        return v == null ? d : v;
    };
}
test('should return last', function () {
    expect(first([1, 2, 3])).toEqual(1);
});
test('empty array', function () {
    expect(first([])).toEqual(undefined);
});
describe('pipe', function () {
    test('as no-fn', function () {
        var counter = createCounter();
        var result = pipe([1, 2, 3, 4, 5, 6], counter.fn(), first, function (x) { return x; });
        expect(counter.count).toHaveBeenCalledTimes(1);
        expect(result).toEqual(1);
    });
    test('as fn', function () {
        var counter = createCounter();
        var result = pipe([1, 2, 3, 4, 5, 6], counter.fn(), first());
        expect(counter.count).toHaveBeenCalledTimes(1);
        expect(result).toEqual(1);
    });
    test('with filter', function () {
        var counter = createCounter();
        var result = pipe([1, 2, 4, 8, 16], counter.fn(), filter(function (x) { return x > 3; }), first(), defaultTo(0), function (x) { return x + 1; });
        expect(counter.count).toHaveBeenCalledTimes(3);
        expect(result).toEqual(5);
    });
    test('empty array', function () {
        var counter = createCounter();
        var result = pipe([], counter.fn(), first());
        expect(counter.count).toHaveBeenCalledTimes(0);
        expect(result).toEqual(undefined);
    });
    test('2 x first()', function () {
        var counter = createCounter();
        var result = pipe([[1, 2, 3], [4, 5], [6]], counter.fn(), first(), defaultTo([]), first());
        expect(counter.count).toHaveBeenCalledTimes(1);
        expect(result).toEqual(1);
    });
    test('complex', function () {
        var counter1 = createCounter();
        var counter2 = createCounter();
        var result = pipe([[1, 2, 3], [1], [4, 5, 6, 7], [1, 2, 3, 4]], counter1.fn(), filter(function (arr) { return arr.length === 4; }), first(), defaultTo([]), counter2.fn(), filter(function (x) { return x % 2 === 1; }), first());
        expect(counter1.count).toHaveBeenCalledTimes(3);
        expect(counter2.count).toHaveBeenCalledTimes(2);
        expect(result).toEqual(5);
    });
});