Add a resolver for jest (#272)

jest.resolver.js

@@ -0,0 +1,15 @@
+// Copyright 2017-2020 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const path = require('path');
+
+module.exports = function resolver (file, config) {
+  if (file.includes('package.json')) {
+    console.error(file, config);
+    return path.join(config.basedir.replace('/src', '/'), file);
+  }
+
+  return config.defaultResolver(file, config);
+};