Michae hartl第12章密码错误

Question

嗨，大家好我又问了另一个问题。 我仍然遇到代码问题，无法找到问题的解决方案。 我跟着每一步，直到出现这个错误。 它说预期nill不等于零。 有人可以帮我解释一下吗？

FAIL["test_password_resets", PasswordResetsTest, 1.7315357209881768]
 test_password_resets#PasswordResetsTest (1.73s)
        Expected nil to not be equal to nil.
        test/integration/password_resets_test.rb:20:in `block in <class:PasswordResetsTest>'

这是我的password_reset_test.rb

require 'test_helper'

class PasswordResetsTest < ActionDispatch::IntegrationTest

  def setup
    ActionMailer::Base.deliveries.clear
    @user = users(:michael)
  end

  test "password resets" do
    get new_password_reset_path
    assert_template 'password_resets/new'
    # Invalid email
    post password_resets_path, params: { password_reset: { email: "" } }
    assert_not flash.empty?
    assert_template 'password_resets/new'
    # Valid email
    post password_resets_path,
         params: { password_reset: { email: @user.email } }
    assert_not_equal @user.reset_digest, @user.reload.reset_digest
    assert_equal 1, ActionMailer::Base.deliveries.size
    assert_not flash.empty?
    assert_redirected_to root_url
    # Password reset form
    user = assigns(:user)
    # Wrong email
    get edit_password_reset_path(user.reset_token, email: "")
    assert_redirected_to root_url
    # Inactive user
    user.toggle!(:activated)
    get edit_password_reset_path(user.reset_token, email: user.email)
    assert_redirected_to root_url
    user.toggle!(:activated)
    # Right email, wrong token
    get edit_password_reset_path('wrong token', email: user.email)
    assert_redirected_to root_url
    # Right email, right token
    get edit_password_reset_path(user.reset_token, email: user.email)
    assert_template 'password_resets/edit'
    assert_select "input[name=email][type=hidden][value=?]", user.email
    # Invalid password & confirmation
    patch password_reset_path(user.reset_token),
          params: { email: user.email,
                    user: { password:              "foobaz",
                            password_confirmation: "barquux" } }
    assert_select 'div#error_explanation'
    # Empty password
    patch password_reset_path(user.reset_token),
          params: { email: user.email,
                    user: { password:              "",
                            password_confirmation: "" } }
    assert_select 'div#error_explanation'
    # Valid password & confirmation
    patch password_reset_path(user.reset_token),
          params: { email: user.email,
                    user: { password:              "foobaz",
                            password_confirmation: "foobaz" } }
    assert is_logged_in?
    assert_not flash.empty?
    assert_redirected_to user
  end
end

和我的password_resets_controller.rb

class PasswordResetsController < ApplicationController
  before_action :get_user,         only: [:edit, :update]
  before_action :valid_user,       only: [:edit, :update]
  before_action :check_expiration, only: [:edit, :update]    # Case (1)

  def new
  end

  def create
    @user = User.find_by(email: params[:password_reset][:email].downcase)
    if @user
      @user.create_reset_digest
      @user.send_password_reset_email
      flash[:info] = "Email sent with password reset instructions"
      redirect_to root_url
    else
      flash.now[:danger] = "Email address not found"
      render 'new'
    end
  end

  def edit
  end

  def update
    if params[:user][:password].empty?                  # Case (3)
      @user.errors.add(:password, "can't be empty")
      render 'edit'
    elsif @user.update_attributes(user_params)          # Case (4)
      log_in @user
      @user.update_attribute(:reset_digest, nil)
      flash[:success] = "Password has been reset."
      redirect_to @user
    else
      render 'edit'                                     # Case (2)
    end
  end

  private

    def user_params
      params.require(:user).permit(:password, :password_confirmation)
    end

    # Before filters

    def get_user
      @user = User.find_by(email: params[:email])
    end

    # Confirms a valid user.
    def valid_user
      unless (@user && @user.activated? &&
              @user.authenticated?(:reset, params[:id]))
        redirect_to root_url
      end
    end

    # Checks expiration of reset token.
    def check_expiration
      if @user.password_reset_expired?
        flash[:danger] = "Password reset has expired."
        redirect_to new_password_reset_url
      end
    end
end

感谢您的帮助。