reside-eng / jest-runtime

Custom runtime for Jest which addresses memory issue

@side/jest-runtime

Custom runtime for Jest which addresses memory leak when using Typescript

NOTE This package was intentionally left as JS instead of being converted to TS because it is only a slight modification of existing Jest code based on this PR

1. Install SWC if you haven't already @swc/core @swc/jest

2. Make sure to configure SWC if you haven't already:

   {
      "jsc": {
         "parser": {
            "syntax": "typescript",
            "decorators": true
         },
         "transform": {
            "legacyDecorator": true,
            "decoratorMetadata": true
         }
      }
   }
   

3. Install custom runtime: yarn add @side/jest-runtime

4. Use within jest.config.js:

   module.exports = {
     transform: {
       '^.+\\.ts$': '@swc/jest',
     },
     runtime: '@side/jest-runtime',
   };

Why?

We were seeing memory leaks using ts-jest with node >16.10. When investigating solutions this PR fixing the issue was noticed. Since it hasn't been merged, and we still wanted to share this logic, we created this lib.