class_docstr: Base tests for `ExperimentIdMiddleware`.
class_docstr_tok: ["Base","tests","for","`","ExperimentIdMiddleware","`","."]
code: def _echo_app(self, environ, start_response):
      # https://www.python.org/dev/peps/pep-0333/#environ-variables
      data = {
          "eid": environ[experiment_id.WSGI_ENVIRON_KEY],
          "path": environ.get("PATH_INFO", ""),
          "script": environ.get("SCRIPT_NAME", ""),
      }
      body = json.dumps(data, sort_keys=True)
      start_response("200 OK", [("Content-Type", "application/json")])
      return [body]
  
imports: import json
  import werkzeug
  from werkzeug import test
  from tensorboard import test
  from tensorboard.backend import experiment_id
label_desc: Use image node_id 1 for calling the BaseTest obj's underlying member method code with example usage: obj._echo_app(environ, start_response) and returns: list