Ruby on rails test error - ruby-on-rails

Question

I am learning to make tests for a ruby on rails application, and I appear to have run into an issue. I am trying to login a user as I do not have access to the session[:user_id] inside these two tests. So I have made a method inside the test_helper that defines these methods in my create_categories_test, and they run, but when I set a login for them, it returns this error:
(byebug) post login_path session: [{username: user.username, password: password}]
*** NoMethodError Exception: undefined method `[]' for nil:NilClass
This is my helper method in test_helper.rb
ENV['RAILS_ENV'] ||= 'test'
require File.expand_path('../../config/environment', __FILE__)
require 'rails/test_help'
class ActiveSupport::TestCase
# Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
fixtures :all
# Add more helper methods to be used by all tests here...
def sign_in_as(user, password)
post login_path, session: {username: user.username, password: password}
end
end
Note: I put a debugger inside my method and ran the same line of code which returned nil(for some reason)
Here's my code for my create_categories_test.rb
def setup
#user = User.create(username: "John", email: "john#doe.com", password: "password", admin: true)
end
test "get new category form and create category" do
sign_in_as(#user, "password")
get new_category_path
assert_template 'categories/new'
assert_difference 'Category.count' do
post_via_redirect categories_path, category: {name: "sports"}
end
assert_template 'categories/index'
assert_match "sports", response.body
end
test "invalid category submission results in failure" do
sign_in_as(#user, "password")
get new_category_path
assert_template 'categories/new'
assert_no_difference 'Category.count', 1 do
post categories_path, category: {name: " "}
end
assert_template 'categories/new'
assert_select 'h2.panel-title'
assert_select 'div.panel-body'
end
My login controller:
class SessionsController < ApplicationController
def new
end
def create
user = User.find_by(username: params[:sessions][:username])
if user && user.authenticate(params[:sessions][:password])
session[:user_id] = user.id
flash[:success] = "You have successfully logged in"
redirect_to user_path(user)
else
flash.now[:danger] = "There was something wrong with your login details"
render 'new'
end
end
def destroy
session[:user_id] = nil
flash[:success] = "You have successfully logged out"
redirect_to root_path
end
end

Answer 1

I assume the problem in your params in the post method:
post login_path session: [{username: user.username, password: password}]
You post an array [{username: user.username, password: password}], but controller expect an hash:
post login_path session: {username: user.username, password: password}
Also your login helper:
#session: {}
post login_path, session: {username: user.username, password: password}
^^^^^^^
But controller expect:
#sessions: {}
user = User.find_by(username: params[:sessions][:username])
^^^^^^^^
Probably this is off-topic question, because it's about a simple typo in the code.