Configure Jest To Run A Test Setup File

Jest can be configured to run a setup file before each test. This is useful for configuring your testing framework in a single place, rather than in each test file.

This setup file can be specified in package.json (or jest.config.js).

// package.json
{
  // ...
  "jest": {
    "setupTestFrameworkScriptFile": "<rootDir>src/setupTests.js"
  }
}

The setupTestFrameworkScriptFile points to a test setup file at the specified location rooted at <rootDir> (the root of your project).

This kind of setup is helpful for something like Enzyme that needs to be configured with a specific adapter for use throughout your tests.