Return a lazy enumerator when no block given to #paginate

Author: sshaw

README.md

@@ -160,6 +160,13 @@ pager.execute(query, :foo => 123) do |page|
 end
 ```
 
+If a block is not given an `Enumerator::Lazy` instance is returned that will fetch the next page upon each iteration:
+
+```rb
+results = pager.execute(query, :foo => 123)
+results.each { |page| ... }
+```
+
 #### `after` Pagination
 
 To use `after` pagination, i.e., to paginate forward, your query must:

lib/shopify_api/graphql/tiny.rb

@@ -348,19 +348,22 @@ def execute(q, variables = nil)
         variables ||= {}
         pagination_finder = @options[@options[:direction]]
 
-        loop do
-          page = @gql.execute(q, variables)
+        enumerator = Enumerator.new do |y|
+          loop do
+            page = @gql.execute(q, variables)
+            y << page
 
-          yield page
+            cursor = pagination_finder[page]
+            break unless cursor
 
-          cursor = pagination_finder[page]
-          break unless cursor
-
-          next_page_variables = variables.dup
-          next_page_variables[@options[:variable]] = cursor
-          #break unless next_page_variables != variables
+            variables[@options[:variable]] = cursor
+          end
+        end
 
-          variables = next_page_variables
+        if block_given?
+          enumerator.each { |page| yield page }
+        else
+          enumerator.lazy
         end
       end
 

spec/shopify_api/graphql/tiny_spec.rb

@@ -456,6 +456,35 @@ def paginate_positions(pager, q, options)
       expect(positions).to eq positions.sort
     end
 
+    it "paginates using a lazy enumerator when no block is given" do
+      q = <<-GQL
+        query product($id: ID! $after: String) {
+          product(id: $id) {
+            variants(first:1 sortKey: POSITION after: $after ) {
+              pageInfo {
+                hasNextPage
+                endCursor
+              }
+              edges {
+                node {
+                  position
+                }
+              }
+            }
+          }
+        }
+      GQL
+
+      enum = client.paginate.execute(q, :id => @id)
+      expect(enum).to be_a(Enumerator::Lazy)
+
+      positions = []
+      enum.each { |page| positions << page.dig(*position_node_at(0)).fetch("position") }
+
+      expect(positions.size).to be > 1, VARIANT_COUNT_ERROR
+      expect(positions).to eq positions.sort
+    end
+
     it "pages backward using a $before variable when :before pagination is specified" do
       q = <<-GQL
         query product($id: ID!) {