Let's create a new file marble-testing.spec.ts. It should look like the following:
// marble-testing\MarbleTesting\src\app\marble-testing.spec.tsimport { cold } from "jasmine-marbles";import "rxjs/add/operator/map";describe("marble tests", () => { it("map - should increase by 1", () => { const one$ = cold("x-x|", { x: 1 }); expect(one$.map(x => x + 1)).toBeObservable(cold("x-x|", { x: 2 })); });});
A lot of interesting things are happening here. We import the function cold() from the NPM library marble-testing. Thereafter we set up a test suite by calling describe(), followed by a test specification, by calling it(). Then we call our cold() function and provide it a string. Let's have a close look at that function ...
