make ts-jest transform JS files

Author: lobsterkatie

packages/utils/jest.config.js

@@ -1 +1,9 @@
-module.exports = require('../../jest/jest.config.js');
+const baseConfig = require('../../jest/jest.config.js');
+
+module.exports = {
+  ...baseConfig,
+  transform: {
+    '^.+\\.ts$': 'ts-jest',
+    '^.+\\.js$': 'ts-jest',
+  },
+};

packages/utils/tsconfig.test.json

@@ -5,8 +5,10 @@
 
   "compilerOptions": {
     // should include all types from `./tsconfig.json` plus types for all test frameworks used
-    "types": ["node", "jest"]
+    "types": ["node", "jest"],
 
     // other package-specific, test-specific options
+    // this is necessary in order to be able to handle the buildPolyfills `originals.js` which is used for testing
+    "allowJs": true
   }
 }