Add support Collection#products endpoint

lib/shopify_api/resources/collection.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module ShopifyAPI
+  class Collection < Base
+    include Events
+    include Metafields
+
+    def products(options = {})
+      available_in_version = ShopifyAPI::ApiVersion.find_version(:unstable)
+      raise NotImplementedError unless ShopifyAPI::Base.api_version >= available_in_version
+      Product.find(:all, from: "#{self.class.prefix}collections/#{id}/products.json", params: options)
+    end
+  end
+end

test/collection_test.rb

@@ -0,0 +1,49 @@
+require 'test_helper'
+
+class CollectionTest < Test::Unit::TestCase
+  test "Collection get products gets all products in a collection on unstable version" do
+    unstable_version = ShopifyAPI::Session.new(domain: 'shop2.myshopify.com', token: 'token2', api_version: :unstable)
+    ShopifyAPI::Base.activate_session(unstable_version)
+
+    fake(
+        'collections',
+        url: 'https://shop2.myshopify.com/admin/api/unstable/collections/1.json',
+        method: :get,
+        status: 200,
+        body: load_fixture('collection'),
+        extension: false
+    )
+
+    collection = ShopifyAPI::Collection.find(1)
+
+    fake(
+        'products',
+        url: 'https://shop2.myshopify.com/admin/api/unstable/collections/1/products.json',
+        method: :get,
+        status: 200,
+        body: load_fixture('collection_products'),
+        extension: false
+    )
+    assert_equal [632910392, 921728736], collection.products.map(&:id)
+  end
+
+  test "Collection get products fails on older api version" do
+    unstable_version = ShopifyAPI::Session.new(domain: 'shop2.myshopify.com', token: 'token2', api_version: '2019-07')
+    ShopifyAPI::Base.activate_session(unstable_version)
+
+    fake(
+        'collections',
+        url: 'https://shop2.myshopify.com/admin/api/2019-07/collections/1.json',
+        method: :get,
+        status: 200,
+        body: load_fixture('collection'),
+        extension: false
+    )
+
+    collection = ShopifyAPI::Collection.find(1)
+
+    assert_raises NotImplementedError do
+      collection.products
+    end
+  end
+end

test/fixtures/collection.json

@@ -0,0 +1,17 @@
+{
+  "collection": {
+    "id": 1,
+    "handle": "test-collection",
+    "title": "test-collection",
+    "updated_at": "2016-03-17T16:58:37-04:00",
+    "body_html": null,
+    "published_at": "2016-03-17T16:58:37-04:00",
+    "sort_order": "alpha-asc",
+    "template_suffix": null,
+    "published_scope": "global",
+    "image": {
+      "created_at": "2016-03-17T16:58:37-04:00",
+      "src": "https:\/\/cdn.shopify.com\/s\/files\/1\/0006\/9093\/3842\/collections\/fd43f2c8883f6e9b680e3295fd990d2c.gif?v=1458248317"
+    }
+  }
+}

test/fixtures/collection_products.json

@@ -0,0 +1,47 @@
+{
+  "products": [
+    {
+      "product_type": "Cult Products",
+      "handle": "ipod-nano",
+      "created_at": "2011-10-20T14:05:13-04:00",
+      "body_html": "<p>It's the small iPod with one very big idea: Video. Now the world's most popular music player, available in 4GB and 8GB models, lets you enjoy TV shows, movies, video podcasts, and more. The larger, brighter display means amazing picture quality. In six eye-catching colors, iPod nano is stunning all around. And with models starting at just $149, little speaks volumes.</p>",
+      "title": "IPod Nano - 8GB",
+      "template_suffix": null,
+      "updated_at": "2011-10-20T14:05:13-04:00",
+      "id": 632910392,
+      "tags": "Emotive, Flash Memory, MP3, Music",
+      "images": [
+        {
+          "position": 1,
+          "created_at": "2011-10-20T14:05:13-04:00",
+          "product_id": 632910392,
+          "updated_at": "2011-10-20T14:05:13-04:00",
+          "src": "http://static.shopify.com/s/files/1/6909/3384/products/ipod-nano.png?0",
+          "id": 850703190
+        }
+      ],
+      "vendor": "Apple",
+      "published_at": "2007-12-31T19:00:00-05:00",
+      "manually_sorted": true,
+      "options": [
+        {
+          "name": "Title"
+        }
+      ]
+    },
+    {
+      "product_type": "Cult Products",
+      "handle": "ipod-touch",
+      "created_at": "2018-09-26T14:05:13-04:00",
+      "body_html": "<p>The iPod Touch has the iPhone's multi-touch interface, with a physical home button off the touch screen. The home screen has a list of buttons for the available applications.</p>",
+      "title": "IPod Touch 8GB",
+      "template_suffix": null,
+      "updated_at": "2018-09-26T14:05:13-04:00",
+      "id": 921728736,
+      "tags": null,
+      "vendor": "Apple",
+      "published_at": "2018-09-26T14:05:13-04:00",
+      "manually_sorted": true
+    }
+  ]
+}