class_docstr: Tests for `AuthContextMiddleware`
code: def test_populates_auth_context(self):
      app = auth_context_middleware.AuthContextMiddleware(
          _create_auth_provider_verifier_app("my_key"),
          {"my_key": SimpleAuthProvider("my_credential")},
      )
  
      server = werkzeug_test.Client(app, wrappers.Response)
      response = server.get("")
      self.assertEqual(
          "credential: my_credential", response.get_data().decode()
      )
  
file_path: tensorboard/tensorboard/backend/auth_context_middleware_test.py
imports: from werkzeug import test
  from werkzeug import wrappers
  from tensorboard import auth
  from tensorboard import context
  from tensorboard import test
  from tensorboard.backend import auth_context_middleware
label_desc: Use image node_id 1 for calling the AuthContextMiddlewareTest obj's underlying member method code with example usage: obj.test_populates_auth_context() without return types