folders.component.spec.ts

  describe("selectFolder", () => {
    it("should update selectedFolder property with passed folder", () => {
      // arrange
      component.selectedFolder = undefined;
      let folder: IFolder = new Folder(1, "Harry Potter");

      // act
      component.selectFolder(folder);

      // assert
      expect(component.selectedFolder).toBe(folder);
    });
  });