strom/tests/concat.spec.ts

import { Readable } from "stream";
import test from "ava";
import { expect } from "chai";
import { strom } from "../src";
const { concat, collect } = strom();

test.cb(
    "concat() concatenates multiple readable streams (object, flowing mode)",
    t => {
        t.plan(6);
        const source1 = new Readable({ objectMode: true });
        const source2 = new Readable({ objectMode: true });
        const expectedElements = ["a", "b", "c", "d", "e", "f"];
        let i = 0;
        concat(source1, source2)
            .on("data", (element: string) => {
                expect(element).to.equal(expectedElements[i]);
                t.pass();
                i++;
            })
            .on("error", t.end)
            .on("end", t.end);

        source1.push("a");
        source2.push("d");
        source1.push("b");
        source2.push("e");
        source1.push("c");
        source2.push("f");
        source2.push(null);
        source1.push(null);
    },
);

test.cb(
    "concat() concatenates multiple readable streams (object, paused mode)",
    t => {
        t.plan(6);
        const source1 = new Readable({ objectMode: true });
        const source2 = new Readable({ objectMode: true });
        const expectedElements = ["a", "b", "c", "d", "e", "f"];
        let i = 0;
        const concatenation = concat(source1, source2)
            .on("readable", () => {
                let element = concatenation.read();
                while (element !== null) {
                    expect(element).to.equal(expectedElements[i]);
                    t.pass();
                    i++;
                    element = concatenation.read();
                }
            })
            .on("error", t.end)
            .on("end", t.end);

        source1.push("a");
        source2.push("d");
        source1.push("b");
        source2.push("e");
        source1.push("c");
        source2.push("f");
        source2.push(null);
        source1.push(null);
    },
);

test.cb(
    "concat() concatenates multiple readable streams (non-object, flowing mode)",
    t => {
        t.plan(6);
        const source1 = new Readable({ objectMode: false });
        const source2 = new Readable({ objectMode: false });
        const expectedElements = ["a", "b", "c", "d", "e", "f"];
        let i = 0;
        concat(source1, source2)
            .on("data", (element: string) => {
                expect(element).to.deep.equal(Buffer.from(expectedElements[i]));
                t.pass();
                i++;
            })
            .on("error", t.end)
            .on("end", t.end);

        source1.push("a");
        source2.push("d");
        source1.push("b");
        source2.push("e");
        source1.push("c");
        source2.push("f");
        source2.push(null);
        source1.push(null);
    },
);

test.cb(
    "concat() concatenates multiple readable streams (non-object, paused mode)",
    t => {
        t.plan(6);
        const source1 = new Readable({ objectMode: false, read: () => ({}) });
        const source2 = new Readable({ objectMode: false, read: () => ({}) });
        const expectedElements = ["a", "b", "c", "d", "e", "f"];
        let i = 0;
        const concatenation = concat(source1, source2)
            .on("readable", () => {
                let element = concatenation.read();
                while (element !== null) {
                    expect(element).to.deep.equal(
                        Buffer.from(expectedElements[i]),
                    );
                    t.pass();
                    i++;
                    element = concatenation.read();
                }
            })
            .on("error", t.end)
            .on("end", t.end);

        source1.push("a");
        setTimeout(() => source2.push("d"), 10);
        setTimeout(() => source1.push("b"), 20);
        setTimeout(() => source2.push("e"), 30);
        setTimeout(() => source1.push("c"), 40);
        setTimeout(() => source2.push("f"), 50);
        setTimeout(() => source2.push(null), 60);
        setTimeout(() => source1.push(null), 70);
    },
);

test.cb("concat() concatenates a single readable stream (object mode)", t => {
    t.plan(3);
    const source = new Readable({ objectMode: true });
    const expectedElements = ["a", "b", "c", "d", "e", "f"];
    let i = 0;
    concat(source)
        .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(
    "concat() concatenates a single readable stream (non-object mode)",
    t => {
        t.plan(3);
        const source = new Readable({ objectMode: false });
        const expectedElements = ["a", "b", "c", "d", "e", "f"];
        let i = 0;
        concat(source)
            .on("data", (element: string) => {
                expect(element).to.deep.equal(Buffer.from(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("concat() concatenates empty list of readable streams", t => {
    t.plan(0);
    concat()
        .pipe(collect())
        .on("data", _ => {
            t.fail();
        })
        .on("error", t.end)
        .on("end", t.end);
});