Chapter 11: Unit Testing with Jest

1. Let's say we are implementing a Jest test and we have a variable called result, which we want to check isn't null. How can we do this with Jest matcher functions?

expect(result).not.toBeNull()

2. Let's say we have variable called person that is of type IPerson:

interface IPerson {
  id: number;
  name: string;
}

We want to check that the person variable is { id: 1, name: "bob" }. How can we do this with Jest matcher functions?

expect(person).not.toBeEqual({ id: 1, name: "bob" });

3. Is it possible to carry out our check in the last question with a Jest snapshot test? If so how?

Yes:

expect(person).toMatchSnapshot();

4. We have implemented a component called CheckList, which renders text from an array in a list. Each list item has a checkbox so that the user can select list items. The component has a function prop...