Clarifying the use of do_test function

Summary: The `do_test` method might be used to perform testing outside the training process. One might think it will load the weights of the models before testing similar to `do_train` method. This diff adds a comment that clarifies this confusion.

Reviewed By: ppwwyyxx

Differential Revision: D29082338

fbshipit-source-id: 6ec7d7f7f243503414fa904f4eb8856e62e9ed6d

d2go/runner/default_runner.py

@@ -386,6 +386,10 @@ class Detectron2GoRunner(BaseRunner):
         return results
 
     def do_test(self, cfg, model, train_iter=None):
+        """ do_test does not load the weights of the model.
+        If you want to use it outside the regular training routine,
+        you will have to load the weights through a checkpointer.
+        """
         results = OrderedDict()
         with maybe_subsample_n_images(cfg) as new_cfg:
             # default model