Added some documentation in comments.

1 files changed, 21 insertions, 1 deletions

diff --git a/js/commonjs/rewrite_tests_for_commonjs.js b/js/commonjs/rewrite_tests_for_commonjs.js
index 4dc0a22d..d49f8a93 100644
--- a/js/commonjs/rewrite_tests_for_commonjs.js
+++ b/js/commonjs/rewrite_tests_for_commonjs.js
@@ -1,5 +1,25 @@
 /**
- * @fileoverview Description of this file.
+ * @fileoverview Utility to translate test files to CommonJS imports.
+ *
+ * This is a somewhat hacky tool designed to do one very specific thing.
+ * All of the test files in *_test.js are written with Closure-style
+ * imports (goog.require()).  This works great for running the tests
+ * against Closure-style generated code, but we also want to run the
+ * tests against CommonJS-style generated code without having to fork
+ * the tests.
+ *
+ * Closure-style imports import each individual type by name.  This is
+ * very different than CommonJS imports which are by file.  So we put
+ * special comments in these tests like:
+ *
+ * // CommonJS-LoadFromFile: test_pb
+ * goog.require('proto.jspb.test.CloneExtension');
+ * goog.require('proto.jspb.test.Complex');
+ * goog.require('proto.jspb.test.DefaultValues');
+ *
+ * This script parses that special comment and uses it to generate proper
+ * CommonJS require() statements so that the tests can run and pass using
+ * CommonJS imports.
  */
 
 var lineReader = require('readline').createInterface({