Single-context Node.js environment for Jest

One of Jest's key features is context isolation so tests can't have side-effects on other tests by manipulating the global context. In theory that's a good idea but in practice the current implementation messes around with global types in a way which breaks pretty much all instanceof checks in tests against standard types like Uint8Array for example.

See Jest issue #2549 for details.

This small project provides a single-context Node.js environment which effectively sacrifices the context isolation feature by using a single context for all tests so instanceof checks works again as expected.

Alternatively you may want to try jest-light-runner which tackles the problem right at the base with a new test runner implementation instead of hacking the standard test runner of Jest.

Usage

• Install dependency:

  npm install -D jest-environment-node-single-context
  

• Add this property to your Jest config:

  testEnvironment: "jest-environment-node-single-context"