Problem

• create-react-app wants to support using src/node_modules for internal packages. This is kind of hacky, but is the least bad of available solutions for the reasons enumerated here.
• Jest sensibly ignores tests in node_modules by default, but even when those defaults are overridden, it still ignores those tests.

This is the jest configuration in package.json:

{
  "moduleFileExtensions": [
    "jsx",
    "js",
    "json"
  ],
  "moduleNameMapper": {
    "^.+\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/config/jest/FileStub.js",
    "^.+\\.css$": "<rootDir>/config/jest/CSSStub.js"
  },
  "setupFiles": [
    "<rootDir>/config/polyfills.js"
  ],
  "testPathIgnorePatterns": [
    "<rootDir>/(build|config|node_modules)/"
  ],
  "preprocessorIgnorePatterns": [
      "<rootDir>/node_modules"
  ],
  "testEnvironment": "node"
}

This should ignore <rootDir>/node_modules, but not <rootDir>/src/node_modules. In fact, even if you set testPathIgnorePatterns to just ["<rootDir>/(build)/"], it still ignores tests in all node_modules directories.

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This project was bootstrapped with Create React App.