Get code coverage for React Testing Library tests

Run:

npm t -- --coverage --watchAll=false

A code coverage report is output in the terminal with the test results, an HTML report is also created in coverage/lcov-report/ folder.

Ignoring files in the coverage report

We can will files such as index.ts, types.ts from the coverage report because they don’t contain any logic and create unnecessary noise.

We can configure Jest in the package.json file in a jest field, there is a converagePathIgnorePatterns configuration option for removing files from the coverage report:

{
 ...
 "jest": {
   "coveragePathIgnorePatterns": [
     "types.ts",
     "index.ts"
   ]
 }
}