Add functionality to re-release a movie

[marlabrizel]

Add functionality that allows a movie to be re-released with an updated year.

Re-releasing a movie should:

• Create a new copy of the movie
• Set the copy's year to the year specified
• Redirect to the newly created movie

Use the following failing test cases to get started:

# test/integration/rereleases_test.rb

require 'test_helper'

class RereleasesTest < ActionDispatch::IntegrationTest
  test "does not alter the original movie year" do
    movie = create(:movie, year: "1985")

    post "/movies/#{movie.id}/rereleases/", params: {
      year: 2020,
    }

    first_release = Movie.find(movie.id)
    assert_equal "1985", movie.year
  end

  test "creates a copy of the movie with the specified year" do
    movie = create(:movie, year: "1985")

    assert_difference(-> { Movie.where(title: movie.title).count }, 1) do
      post "/movies/#{movie.id}/rereleases/", params: {
        year: 2020,
      }
    end

    rerelease = Movie.find_by(title: movie.title, year: 2020)
    assert_equal "2020", rerelease.year
  end

  test "redirects to movie rerelease show page" do
    movie = create(:movie, year: "1985")

    post "/movies/#{movie.id}/rereleases/", params: {
      year: 2020,
    }

    rerelease = Movie.find_by(title: movie.title, year: 2020)
    assert_redirected_to movie_path(rerelease)
  end
end