How to test behavior of React components (changing state or classes after simulate("event") with Enzyme?

Question

JavaScript

Hello!
I started to delve a little into Enzyme, the question is this: I want to test the behavior in which, after clicking on the button, a new class is added to the input (if it has an empty value). Here is my listing:

it("Search component should mark empty input as invalid after click on button", () => {
    const searchComponent = mount<Search, TSearchProps, ISearchState>(<Search onSearch={{}}/>);
    const searchButton = searchComponent.find(".search__button");
    const searchInput = searchComponent.find(".search__input");

    searchInput.simulate("change", {
      target: {
        value: "",
      },
    });
    searchButton.simulate("click");
    searchComponent.update();

    expect(searchInput.hasClass("search__input_invalid"))
      .toBe(true);
  });

The test fails (although the class is indeed added, although searchComponent.debug() thinks otherwise)
The same question, but with the component state. Here is the resulting listing:

it("Search component should set previous artist name to state in lowercase", () => {
    const searchComponent = mount<Search, TSearchProps, ISearchState>(<Search onSearch={{}}/>);
    const searchInput = searchComponent.find(".search__input");
    const searchButton = searchComponent.find(".search__button");

    const expectedPreviousArtistName = "sting";

    searchInput.simulate("change", {
      target: {
        value: "StiNg",
      },
    });
    searchComponent.update();
    searchButton.simulate("click");
    searchComponent.update();

    expect(searchComponent.state().previousArtistName)
      .toBe(expectedPreviousArtistName);
  });

The test fails, saying that the artist's name is empty.
Thank you all so much for your time!