parallel-es/test/common/parallel/slave/reduce-iterator.specs.ts

Simple parallelization for EcmaScript

import {reduceIterator} from "../../../../src/common/parallel/slave/reduce-iterator";
import {toIterator} from "../../../../src/common/util/arrays";
import {IParallelTaskEnvironment} from "../../../../src/common/parallel";

describe("reduceIterator", function () {
    let environment: IParallelTaskEnvironment;

    beforeEach(function () {
        environment = { taskIndex: 2, valuesPerTask: 2 };
    });

    it("returns the default value if the passed iterator is empty", function () {
        // arrange
        const iterator = toIterator([]);

        // act
        const result = reduceIterator(100, iterator, (memo, value) => memo + value, environment).next().value;

        // assert
        expect(result).toBe(100);
    });

    it("applies the accumulator for each value of the passed iterator", function () {
        // arrange
        const iterator = toIterator([1, 2, 3, 4]);
        const accumulator = jasmine.createSpy("accumulator");
        accumulator.and.callFake((memo: number, value: number) => memo + value);

        // act
        reduceIterator(0, iterator, accumulator, environment).next();

        // assert
        expect(accumulator).toHaveBeenCalledWith(0, 1, environment);
        expect(accumulator).toHaveBeenCalledWith(1, 2, environment);
        expect(accumulator).toHaveBeenCalledWith(3, 3, environment);
        expect(accumulator).toHaveBeenCalledWith(6, 4, environment);
    });

    it("returns the accumulated value", function () {
        // arrange
        const iterator = toIterator([1, 2, 3, 4]);
        const accumulator = (memo: number, value: number) => memo + value;

        // act
        const result = reduceIterator(0, iterator, accumulator, environment).next().value;

        // assert
        expect(result).toBe(10);
    });
});