class_docstr: Tests for `PathPrefixMiddleware`.
class_docstr_tok: ["Tests","for","`","PathPrefixMiddleware","`","."]
code: def test_empty_path_prefix(self):
      app = path_prefix.PathPrefixMiddleware(self._echo_app, "")
      server = werkzeug_test.Client(app, werkzeug.wrappers.Response)
  
      with self.subTest("at empty"):
          self._assert_ok(server.get(""), path="", script="")
  
      with self.subTest("at root"):
          self._assert_ok(server.get("/"), path="/", script="")
  
      with self.subTest("at subpath"):
          response = server.get("/foo/bar")
          self._assert_ok(
              server.get("/foo/bar"), path="/foo/bar", script=""
          )
  
file_path: tensorboard/tensorboard/backend/path_prefix_test.py
imports: import json
  import werkzeug
  from werkzeug import test
  from tensorboard import errors
  from tensorboard import test
  from tensorboard.backend import path_prefix
label_desc: Use image node_id 5 for calling the PathPrefixMiddlewareTest obj's underlying member method code with example usage: obj.test_empty_path_prefix() without return types