Marble testing with TestScheduler and pokemon

marble-testing-pokemon.spec.ts

import { TestScheduler } from "rxjs/testing";
import { filter, map } from "rxjs/operators";

describe("Awesome testing with Marble Diagrams", () => {
  const scheduler = new TestScheduler((actual, expected) => {
    expect(actual).toEqual(expected);
  });

  it("should filter non-Water type pokemon and add attack property", () => {
    scheduler.run(({ cold, expectObservable }) => {
      const values = {
        a: { name: "Bulbasur", type: "Grass" },
        b: { name: "Charmander", type: "Fire" },
        c: { name: "Squirtle", type: "Water" }
      };

      const marbleDiagram = "-a-b-c|";
      const pokemon$ = cold(marbleDiagram, values);

      const expectedMarbleDiagram = "-----c|";
      const expectedValues = {
        c: { name: "Squirtle", type: "Water", attack: 30 }
      };
      const result = pokemon$.pipe(
        filter(({ type }) => type === "Water"),
        map(pokemon => ({ ...pokemon, attack: 30 }))
      );

      expectObservable(result).toBe(expectedMarbleDiagram, expectedValues);
    });
  });
});