React: Testing and Debugging

Question 1

What’s the name of the testing package that comes out of the box with create-react-app?

Answer 1

Jest

Question 2

What library can you use for type-checking?

Answer 2

Flow

Question 3

How do you initialize flow?

Answer 3

After having installed the npm package, and having added a “flow” target to react scripts that simply runs “flow, you run npm run flow init.

Question 4

How do you tell flow to check the types of a file?

Answer 4

You add a comma to the first line of that file that reads “ // @flow