Add JSON support for GET /my/pins with no pagination and tests.

app/controllers/my/pins_controller.rb

@@ -1,6 +1,15 @@
 class My::PinsController < ApplicationController
   def index
-    @pins = Current.user.pins.includes(:card).ordered.limit(20)
+    @pins = pins_for_request
     fresh_when etag: [ @pins, @pins.collect(&:card) ]
   end
+
+  private
+    def pins_for_request
+      if request.format.json?
+        Current.user.pins.includes(:card).ordered
+      else
+        Current.user.pins.includes(:card).ordered.limit(20)
+      end
+    end
 end

app/views/my/pins/index.json.jbuilder

@@ -0,0 +1,3 @@
+json.array! @pins do |pin|
+  json.partial! "cards/card", card: pin.card
+end

test/controllers/my/pins_controller_test.rb

@@ -11,4 +11,14 @@ class My::PinsControllerTest < ActionDispatch::IntegrationTest
     assert_response :success
     assert_select "div", text: /#{users(:kevin).pins.first.card.title}/
   end
+
+  test "index as JSON" do
+    expected_ids = users(:kevin).pins.ordered.pluck(:card_id)
+
+    get my_pins_path(format: :json)
+
+    assert_response :success
+    assert_equal expected_ids.count, @response.parsed_body.count
+    assert_equal expected_ids, @response.parsed_body.map { |card| card["id"] }
+  end
 end