Rails - "Comment.count" didn't change by 1

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Nowadays, I'm building my movie review website on Ruby on Rails but stuck with the Comment.count error. Already checked and tried a lot of options, but any solutions didn't work. Actually, my website works well, but still this test says the error, and I don't understand what is the problem and why it happens. Could you help me to fix this error? Thank you.

error code

 test_comment_interface#CommentsInterfaceTest (3.43s)
        "Comment.count" didn't change by 1.
        Expected: 39
          Actual: 38
        test/integration/comments_interface_test.rb:19:in `block in <class:CommentsInterfaceTest>'

1. comments_interface_test

require 'test_helper'

class CommentsInterfaceTest < ActionDispatch::IntegrationTest
  
  def setup
    @user = users(:michael)
  end
  
  test "comment interface" do
    log_in_as(@user)
    get root_path
    assert_select 'div.pagination'
    
    assert_no_difference 'Comment.count' do
      post comments_path, params: { comment: { content: "" } }
    end
    assert_select 'div#error_explanation'
    content = "This comment really ties the room together"
    assert_difference 'Comment.count', 1 do  #<-----------------------error point
      post comments_path, params: { comment: { content: content } }
    end
    assert_redirected_to root_url
    follow_redirect!
    assert_match content, response.body
    assert_select 'a', text: 'delete'
    first_comment = @user.comments.paginate(page: 1).first
    assert_difference 'Comment.count', -1 do
      delete comment_path(first_comment)
    end
    get user_path(users(:archer))
    assert_select 'a', text: 'delete', count: 0
  end
end

2. comment.rb

class Comment < ApplicationRecord
  belongs_to :user
  belongs_to :movie, optional: true, primary_key: "id"
  has_many :favorites, dependent: :destroy
  
  
  default_scope -> { order(created_at: :desc) }
  validates :user_id,   presence: true
  validates :movie_id,  presence: true
  validates :content,   presence: true, length: { maximum: 250}
  
end

3. comments_controller

class CommentsController < ApplicationController
  include HTTParty
  before_action :logged_in_user, only: [:create, :destroy]
  before_action :correct_user,   only: :destroy
  
  def create
    @comment = current_user.comments.build(comment_params)
    comment_count = Comment.where(movie_id: params[:id]).where(user_id: current_user.id).count
 
    if @comment.valid?
      if comment_count < 1
        @comment.save
        flash[:success] = "Comment created!"
        redirect_to root_url
      else
        flash[:success] = "Can't post a comment twice on the same movie"
        redirect_to request.referrer || root_url
      end
      
    else
      @feed_items = []
      render 'static_pages/home'
    end
  end
  
  def destroy
    @comment.destroy
    flash[:success] = "Comment deleted"
    redirect_to request.referrer || root_url
  end
  
  def edit
    @movie_info = Movie.details(params[:movie_id])
    @comment = Comment.find(params[:id])
    
    if Movie.exists?(@movie_info["id"])
      @movie_db = Movie.find(@movie_info["id"])
      @comments = @movie_db.comments.paginate(page: params[:page])
    end
  end
  
  def update
    @comment = Comment.find(params[:id])
    if @comment.update(comment_params)
      redirect_to root_url
    else
      render :edit
    end
  end
  
  private
  
    def comment_params
      params.require(:comment).permit(:content)
    end
    
    def correct_user
      @comment = current_user.comments.find_by(id: params[:id])
      redirect_to root_url if @comment.nil?
    end
end

4. comments_controller_test

require 'test_helper'

class CommentsControllerTest < ActionDispatch::IntegrationTest
  
  def setup
    @user = users(:michael)
    @comment = comments(:orange)
  end
  
  test "should redirect create when not logged in" do
    assert_no_difference 'Comment.count' do
      post comments_path, params: { comment: { content: "Lorem ipsum" } }
    end
    assert_redirected_to login_url
  end
  
  test "should redirect destroy when not logged in" do
    assert_no_difference 'Comment.count' do
      delete comment_path(@comment)
    end
    assert_redirected_to login_url
  end
  
  test "should redirect destroy for wrong comment" do
    log_in_as(users(:michael))
    comment = comments(:ants)
    assert_no_difference 'Comment.count' do
      delete comment_path(comment)
    end
    assert_redirected_to root_url
  end
end

5. comments.yml

orange:
  content: "I just ate an orange!"
  created_at: <%= 10.minutes.ago %>
  user: michael
  movie: harry
  
tau_manifesto:
  content: "Check out the @tauday site by @mhartl: http://tauday.com"
  created_at: <%= 3.years.ago %>
  user: michael
  movie: harry
  
cat_video:
  content: "Sad cats are sad: http://youtu.be/PKffm2uI4dk"
  created_at: <%= 2.hours.ago %>
  user: michael
  movie: harry
  
most_recent:
  content: "Writing a short test"
  created_at: <%= Time.zone.now.to_s(:db) %>
  user: michael
  movie: harry
  
<% 30.times do |n| %>
comment_<%= n %>:
  content: <%= Faker::Lorem.sentence(5) %>
  created_at: <%= 42.days.ago %>
  user: michael
  movie: harry
<% end %>

ants:
  content: "Oh, is that what you want? Because that's how you get ants!"
  created_at: <%= 2.years.ago %>
  user: archer
  movie: harry

zone:
  content: "Danger zone!"
  created_at: <%= 3.days.ago %>
  user: archer
  movie: harry

tone:
  content: "I'm sorry. Your words made sense, but your sarcastic tone did not."
  created_at: <%= 10.minutes.ago %>
  user: lana
  movie: harry

van:
  content: "Dude, this van's, like, rolling probable cause."
  created_at: <%= 4.hours.ago %>
  user: lana
  movie: harry

From the comments below, I fixed some codes like this. Finally it worked, and the problem was solved.

1. comments_interface_test

  def setup
    @user  = users(:michael)
    @movie = movies(:harry)  #add
  end

  assert_difference 'Comment.count', 1 do
      post comments_path, params: { comment: { content: content, movie_id: @movie.id } } #fixed
  end

3. comments_controller

  private
  
    def comment_params
      params.require(:comment).permit(:content, :movie_id) #fixed
    end