Improve spec coverage and clean up api/v1/domain_blocks controller (#3466)

app/controllers/api/v1/domain_blocks_controller.rb

@@ -1,18 +1,16 @@
 # frozen_string_literal: true
 
 class Api::V1::DomainBlocksController < ApiController
+  BLOCK_LIMIT = 100
+
   before_action -> { doorkeeper_authorize! :follow }
   before_action :require_user!
+  after_action :insert_pagination_headers, only: :show
 
   respond_to :json
 
   def show
-    @blocks = AccountDomainBlock.where(account: current_account).paginate_by_max_id(limit_param(100), params[:max_id], params[:since_id])
-
-    next_path = api_v1_domain_blocks_url(pagination_params(max_id: @blocks.last.id))    if @blocks.size == limit_param(100)
-    prev_path = api_v1_domain_blocks_url(pagination_params(since_id: @blocks.first.id)) unless @blocks.empty?
-
-    set_pagination_headers(next_path, prev_path)
+    @blocks = load_domain_blocks
     render json: @blocks.map(&:domain)
   end
 
@@ -28,6 +26,46 @@ class Api::V1::DomainBlocksController < ApiController
 
   private
 
+  def load_domain_blocks
+    account_domain_blocks.paginate_by_max_id(
+      limit_param(BLOCK_LIMIT),
+      params[:max_id],
+      params[:since_id]
+    )
+  end
+
+  def account_domain_blocks
+    current_account.domain_blocks
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def next_path
+    if records_continue?
+      api_v1_domain_blocks_url pagination_params(max_id: pagination_max_id)
+    end
+  end
+
+  def prev_path
+    unless @blocks.empty?
+      api_v1_domain_blocks_url pagination_params(since_id: pagination_since_id)
+    end
+  end
+
+  def pagination_max_id
+    @blocks.last.id
+  end
+
+  def pagination_since_id
+    @blocks.first.id
+  end
+
+  def records_continue?
+    @blocks.size == limit_param(BLOCK_LIMIT)
+  end
+
   def pagination_params(core_params)
     params.permit(:limit).merge(core_params)
   end