old_contents: const { defaults } = require("jest-config");
  
  module.exports = {
    testEnvironment: "node",
      setupFiles: [
        "<rootDir>/../apollo-server-env/dist/index.js"
      ],
      preset: "ts-jest",
      testMatch: null,
      testRegex: "/__tests__/.*\\.test\\.(js|ts)$",
      testPathIgnorePatterns: [
        "/node_modules/",
        "/dist/"
      ],
      moduleFileExtensions: [...defaults.moduleFileExtensions, "ts", "tsx"],
      moduleNameMapper: {
        '^__mocks__/(.*)$': '<rootDir>/../../__mocks__/$1',
        '^(?!apollo-server-env|apollo-engine-reporting-protobuf)(apollo-(?:server|datasource|cache-control|tracing|engine)[^/]*|graphql-extensions)(?:/dist)?((?:/.*)|$)': '<rootDir>/../../packages/$1/src$2'
      },
      clearMocks: true,
      globals: {
        "ts-jest": {
          tsConfig: "<rootDir>/src/__tests__/tsconfig.json",
          diagnostics: false
        }
      }
  };
  
new_contents: const { defaults } = require("jest-config");
  
  module.exports = {
    testEnvironment: "node",
      setupFiles: [
        "<rootDir>/../apollo-server-env/dist/index.js"
      ],
      preset: "ts-jest",
      testMatch: null,
      testRegex: "/__tests__/.*\\.test\\.(js|ts)$",
      testPathIgnorePatterns: [
        "/node_modules/",
        "/dist/"
      ],
      moduleFileExtensions: [...defaults.moduleFileExtensions, "ts", "tsx"],
      moduleNameMapper: {
        '^__mocks__/(.*)$': '<rootDir>/../../__mocks__/$1',
        // This regex should match the packages that we want compiled from source
        // through `ts-jest`, as opposed to loaded from their output files in
        // `dist`.
        // We don't want to match `apollo-server-env` and
        // `apollo-engine-reporting-protobuf`, because these don't depend on
        // compilation but need to be initialized from as parto of `prepare`.
        '^(?!apollo-server-env|apollo-engine-reporting-protobuf)(apollo-(?:server|datasource|cache-control|tracing|engine)[^/]*|graphql-extensions)(?:/dist)?((?:/.*)|$)': '<rootDir>/../../packages/$1/src$2'
      },
      clearMocks: true,
      globals: {
        "ts-jest": {
          tsConfig: "<rootDir>/src/__tests__/tsconfig.json",
          diagnostics: false
        }
      }
  };
  
subject: Add comments to `moduleNameMapper` option in Jest config