Hartl Section 9.1.3: test_unsuccessful_edit fails with error ParameterMissing "user" - railstutorial.org

Question

I'm running through Michael Hartl's Ruby on Rails Tutorial, and have run into a problem I have been unable to troubleshoot. The test for editing users (users_edit_test.rb) fails for reasons I don't understand. Since the tutorial is mostly an exercise in copying code, if have checked and double-checked my typing, but I can't find where I messed up. And, more importantly, I want to understand what is going on. Any help you can provide would be appreciated.
The error message (included below) seems to indicate that the test is launching the edit method in the users controller (users_controller.rb), which in turn launches the private user_params method in the same controller. The user_params method sets strong parameters that require the user parameter, and permit the name, email, password, and password_confirmation parameters. The user parameter does not exist when the test runs, so it returns the error.
My first question is, "What is the user parameter?" The name, email, password, and password_confirmation parameters all refer to columns in the users database, and there is also an id column. But there is no user column. The test and the controller both have an #user variable. Is that the user parameter? That doesn't seem to make sense, as I ought to be able to call the variable whatever I want to, right? I feel like there is something fundamental here that I am not getting, and if I got it, I could troubleshoot this and answer the second question, "What did I screw up/how do I fix this?", myself.
users_edit_test.rb
require 'test_helper'
class UsersEditTest < ActionDispatch::IntegrationTest
def setup
#user = users(:michael)
end
test "unsuccessful edit" do
get edit_user_path(#user)
#assert_template 'users/edit'
#patch user_path(#user), user: { name: "",
# email: "foo#invalid",
# password: "foo",
# password_confirmation: "bar" }
#assert_template 'users/edit'
end
end
users_controller.rb
class UsersController < ApplicationController
def show
#user = User.find(params[:id])
end
def new
#user = User.new
end
def create
#user = User.new(user_params)
if #user.save
log_in #user
flash[:success] = "Welcome to the Sample App!"
redirect_to #user
else
render 'new'
end
end
def edit
#user = User.find(params[:id])
if #user.update_attributes(user_params)
# Handle a successful update.
else
render 'edit'
end
end
private
def user_params
params.require(:user).permit(:name,
:email,
:password,
:password_confirmation)
end
end
users.yml
michael:
name: Michael Example
email: michael#example.com
password_digest: <%= User.digest('password') %>
Test Output
Started
ERROR["test_unsuccessful_edit", UsersEditTest, 2015-05-14 00:05:19 +0000]
test_unsuccessful_edit#UsersEditTest (1431561919.08s)
ActionController::ParameterMissing:
ActionController::ParameterMissing: param is missing or the value is empty: user
app/controllers/users_controller.rb:34:in user_params
app/controllers/users_controller.rb:24:in edit
test/integration/users_edit_test.rb:10:in block in class:UsersEditTest
app/controllers/users_controller.rb:34:in user_params
app/controllers/users_controller.rb:24:in edit
test/integration/users_edit_test.rb:10:in block in class:UsersEditTest
27/27:
[==================================================================]
100% Time: 00:00:00, Time: 00:00:00
Finished in 0.69446s 27 tests, 60 assertions, 0 failures, 1 errors, 0 skips

Answer 1

For starters: you probably should start your test with a log_in as(#user) before get edit_user_path(#user).
That is part of the question: the logged in user provides the params-info you are looking for.
The params are sent by the browser, to one of the controller actions. This is probably one of the hard parts when you are starting Rails; you may want to find some info on the request/response cycle in rails, and how they are mapped to the controller actions.
(And by the way, why are your test lines commented out in your question?)

Answer 2

You should implement method Update, then there is no errors.
def edit
#user = User.find(params[:id])
end
def update
#user = User.find(params[:id])
if #user.update_attributes(user_params)
flash[:success] = "Profile updated"
redirect_to #user
else
render 'edit'
end
end