rc-js-util/src/map/impl/map-concat.spec.ts

A collection of TS and C++ utilities to help writing performant and correct applications, achieved through strict typing and (removable) invariant checking.

import { mapConcat } from "./map-concat.js";
import { Test_setDefaultFlags } from "../../test-util/test_set-default-flags.js";

describe("=> mapConcat", () =>
{
    beforeEach(() =>
    {
        Test_setDefaultFlags();
    });

    const values = new Map([["a", [1]]]);

    it("| concats where array exists", () =>
    {
        mapConcat(values, "a", [2]);
        expect(values.get("a")).toEqual([1, 2]);
    });

    it("| creates a copy of the array where key not defined", () =>
    {
        const original = [3];
        mapConcat(values, "b", [3]);
        expect(values.get("b")).toEqual([3]);
        expect(values.get("b"))
            .withContext("the original should be copied")
            .not
            .toBe(original);
    });
});