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garethsongarethson
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Implements relative cursor pagination.
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‎lib/active_resource/collection_ext.rb

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require 'shopify_api/collection_pagination'
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module ActiveResource
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class Collection
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prepend ShopifyAPI::CollectionPagination
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end
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end

‎lib/shopify_api.rb

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require 'shopify_api/defined_versions'
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require 'shopify_api/api_version'
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require 'active_resource/json_errors'
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require 'active_resource/collection_ext'
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require 'shopify_api/disable_prefix_check'
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module ShopifyAPI
@@ -21,6 +22,7 @@ module ShopifyAPI
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require 'shopify_api/resources'
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require 'shopify_api/session'
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require 'shopify_api/connection'
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require 'shopify_api/pagination_link_headers'
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if ShopifyAPI::Base.respond_to?(:connection_class)
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ShopifyAPI::Base.connection_class = ShopifyAPI::Connection

‎lib/shopify_api/collection_pagination.rb

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module ShopifyAPI
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module CollectionPagination
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def next_page?
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next_page_info.present?
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end
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def previous_page?
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previous_page_info.present?
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end
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def fetch_next_page
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fetch_page(next_page_info)
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end
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def fetch_previous_page
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fetch_page(previous_page_info)
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end
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private
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AVAILABLE_IN_VERSION = ShopifyAPI::ApiVersion::Unstable.new
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def fetch_page(page_info)
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return [] unless page_info
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resource_class.where(original_params.merge(page_info: page_info))
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end
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def previous_page_info
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@previous_page_info ||= extract_page_info(pagination_link_headers.previous_link)
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end
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def next_page_info
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@next_page_info ||= extract_page_info(pagination_link_headers.next_link)
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end
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def extract_page_info(link_header)
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raise NotImplementedError unless ShopifyAPI::Base.api_version >= AVAILABLE_IN_VERSION
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return nil unless link_header.present?
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CGI.parse(link_header.url.query)["page_info"][0]
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end
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def pagination_link_headers
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@pagination_link_headers ||= ShopifyAPI::PaginationLinkHeaders.new(
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ShopifyAPI::Base.connection.response["Link"]
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)
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end
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end
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end

‎lib/shopify_api/pagination_link_headers.rb

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module ShopifyAPI
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class InvalidPaginationLinksError < StandardError; end
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class PaginationLinkHeaders
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LinkHeader = Struct.new(:url, :rel)
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attr_reader :previous_link, :next_link
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def initialize(link_header)
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links = parse_link_header(link_header)
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@previous_link = links.find { |link| link.rel == :previous }
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@next_link = links.find { |link| link.rel == :next }
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self
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end
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private
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def parse_link_header(link_header)
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return [] unless link_header.present?
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links = link_header.split(',')
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links.map do |link|
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parts = link.split('; ')
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raise ShopifyAPI::InvalidPaginationLinksError.new("Invalid link header: url and rel expected") unless parts.length == 2
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url = parts[0][/<(.*)>/, 1]
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rel = parts[1][/rel="(.*)"/, 1]&.to_sym
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url = URI.parse(url)
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LinkHeader.new(url, rel)
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end
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end
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end
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end

‎test/pagination_test.rb

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require 'test_helper'
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class PaginationTest < Test::Unit::TestCase
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def setup
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super
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@version = ShopifyAPI::ApiVersion::Unstable.new
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ShopifyAPI::Base.api_version = @version.to_s
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@next_page_info = "eyJkaXJlY3Rpb24iOiJuZXh0IiwibGFzdF9pZCI6NDQwMDg5NDIzLCJsYXN0X3ZhbHVlIjoiNDQwMDg5NDIzIn0%3D"
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@previous_page_info = "eyJsYXN0X2lkIjoxMDg4MjgzMDksImxhc3RfdmFsdWUiOiIxMDg4MjgzMDkiLCJkaXJlY3Rpb24iOiJuZXh0In0%3D"
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@next_link_header = "<https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@next_page_info}>; rel=\"next\""
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@previous_link_header = "<https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@previous_page_info}>; rel=\"previous\""
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end
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test "navigates using next and previous link headers" do
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link_header =
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"<https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@previous_page_info}>; rel=\"previous\",\
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<https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@next_page_info}>; rel=\"next\""
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => link_header
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orders = ShopifyAPI::Order.all
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fake(
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'orders',
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url: "https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@next_page_info}",
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method: :get,
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status: 200,
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body: load_fixture('orders')
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)
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next_page = orders.fetch_next_page
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assert_equal 450789469, next_page.first.id
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fake(
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'orders',
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url: "https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@previous_page_info}",
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method: :get,
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status: 200,
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body: load_fixture('orders')
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)
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previous_page = orders.fetch_previous_page
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assert_equal 450789469, next_page.first.id
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end
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test "retains previous querystring parameters" do
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fake(
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'orders',
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method: :get,
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status: 200,
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api_version: @version,
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url: "https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?fields=id%2Cupdated_at",
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body: load_fixture('orders'),
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link: @next_link_header
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)
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orders = ShopifyAPI::Order.where(fields: 'id,updated_at')
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fake(
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'orders',
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method: :get,
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status: 200,
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api_version: @version,
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url: "https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?fields=id%2Cupdated_at&page_info=#{@next_page_info}",
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body: load_fixture('orders')
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)
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next_page = orders.fetch_next_page
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assert_equal 450789469, next_page.first.id
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end
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test "returns empty next page if just the previous page is present" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => @previous_link_header
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orders = ShopifyAPI::Order.all
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next_page = orders.fetch_next_page
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assert_empty next_page
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end
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test "returns an empty previous page if just the next page is present" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => @next_link_header
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orders = ShopifyAPI::Order.all
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next_page = orders.fetch_previous_page
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assert_empty next_page
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end
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test "#next_page? returns true if next page is present" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => @next_link_header
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orders = ShopifyAPI::Order.all
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assert orders.next_page?
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end
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test "#next_page? returns false if next page is not present" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => @previous_link_header
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orders = ShopifyAPI::Order.all
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refute orders.next_page?
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end
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test "#previous_page? returns true if previous page is present" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => @previous_link_header
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orders = ShopifyAPI::Order.all
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assert orders.previous_page?
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end
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test "#previous_page? returns false if next page is not present" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => @next_link_header
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orders = ShopifyAPI::Order.all
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refute orders.previous_page?
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end
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test "pagination handles no link headers" do
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders')
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orders = ShopifyAPI::Order.all
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refute orders.next_page?
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refute orders.previous_page?
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assert_empty orders.fetch_next_page
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assert_empty orders.fetch_previous_page
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end
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test "raises on invalid pagination links" do
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link_header = "<https://this-is-my-test-shop.myshopify.com/admin/api/unstable/orders.json?page_info=#{@next_page_info}>;"
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fake 'orders', :method => :get, :status => 200, api_version: @version, :body => load_fixture('orders'), :link => link_header
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orders = ShopifyAPI::Order.all
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assert_raises ShopifyAPI::InvalidPaginationLinksError do
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orders.fetch_next_page
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end
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end
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test "raises on an invalid API version" do
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version = ShopifyAPI::ApiVersion::Release.new('2019-04')
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ShopifyAPI::Base.api_version = version.to_s
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fake 'orders', :method => :get, :status => 200, api_version: version, :body => load_fixture('orders')
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orders = ShopifyAPI::Order.all
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assert_raises NotImplementedError do
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orders.fetch_next_page
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end
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end
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end

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