Only collect code coverage in CI (deephaven#714)

README.md

@@ -27,6 +27,8 @@ We are still using node 16.x and npm 8.x. If you are [using nvm](https://github.
 
   Note that log messages from other sources such as react prop types will still be printed since they do not go through our logger.
 
+  If you want to collect coverage locally, run `npm test -- --coverage`
+
 - `npm run build`: Create a production build of all packages. Mainly used by CI when packaging up a production version of the app.
 
 ## Package Overview

jest.config.cjs

@@ -10,6 +10,6 @@ module.exports = {
     'jest-watch-typeahead/testname',
     'jest-watch-select-projects',
   ],
-  collectCoverage: true,
+  collectCoverage: process.env.CI === 'true',
   collectCoverageFrom: ['./src/**/*.{js,ts,jsx,tsx}'], // This is relative to individual project root due to how Jest handles it
 };