Add preprocessor for jest tests

Author: dweber019

.gitignore

@@ -30,3 +30,4 @@ dist/
 src/**/*.js
 test/**/*.js
 coverage/
+!test/preprocessor.js

test/preprocessor.js

@@ -0,0 +1,13 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+const tsc = require('typescript');
+const tsConfig = require('./../tsconfig.json');
+
+module.exports = {
+  process(src, path) {
+    if (path.endsWith('.ts') || path.endsWith('.tsx')) {
+      return tsc.transpile(src, tsConfig.compilerOptions, path, []);
+    }
+    return src;
+  },
+};