strom/tests/map.spec.ts

import { Readable } from "stream";
import test from "ava";
import { expect } from "chai";
import { map } from "../src";

test.cb("map() maps elements synchronously", t => {
    t.plan(3);
    const source = new Readable({ objectMode: true });
    const mapStream = map((element: string) => element.toUpperCase(), {
        objectMode: true,
    });
    const expectedElements = ["A", "B", "C"];
    let i = 0;
    source
        .pipe(mapStream)
        .on("data", (element: string) => {
            expect(element).to.equal(expectedElements[i]);
            t.pass();
            i++;
        })
        .on("error", t.end)
        .on("end", t.end);

    source.push("a");
    source.push("b");
    source.push("c");
    source.push(null);
});

test.cb("map() maps elements asynchronously", t => {
    t.plan(3);
    const source = new Readable({ objectMode: true });
    const mapStream = map(
        async (element: string) => {
            await Promise.resolve();
            return element.toUpperCase();
        },
        { objectMode: true },
    );
    const expectedElements = ["A", "B", "C"];
    let i = 0;
    source
        .pipe(mapStream)
        .on("data", (element: string) => {
            expect(element).to.equal(expectedElements[i]);
            t.pass();
            i++;
        })
        .on("error", t.end)
        .on("end", t.end);

    source.push("a");
    source.push("b");
    source.push("c");
    source.push(null);
});