Fix hasNextPage when max_page_size is set

Author: rmosolgo

lib/graphql/pagination/array_connection.rb

@@ -35,10 +35,10 @@ def index_from_cursor(cursor)
       def load_nodes
         @nodes ||= begin
           sliced_nodes = if before && after
-            end_idx = index_from_cursor(before)-1
+            end_idx = index_from_cursor(before) - 2
             end_idx < 0 ? [] : items[index_from_cursor(after)..end_idx] || []
           elsif before
-            end_idx = index_from_cursor(before)-2
+            end_idx = index_from_cursor(before) - 2
             end_idx < 0 ? [] : items[0..end_idx] || []
           elsif after
             items[index_from_cursor(after)..-1] || []
@@ -56,7 +56,7 @@ def load_nodes
             false
           end
 
-          @has_next_page = if first
+          @has_next_page = if first_value && first
             # There are more items after these items
             sliced_nodes.count > first
           elsif before

lib/graphql/pagination/relation_connection.rb

@@ -31,7 +31,7 @@ def has_next_page
         if @has_next_page.nil?
           @has_next_page = if before_offset && before_offset > 0
             true
-          elsif first
+          elsif first && first_value
             if @nodes && @nodes.count < first
               false
             else

spec/support/connection_assertions.rb

@@ -243,6 +243,18 @@ def assert_names(expected_names, result)
           refute get_page_info(res3, "hasPreviousPage")
         end
 
+        it "returns empty lists for `after: 1` and `before: 2`" do
+          res = exec_query(query_str, first: 2)
+          assert_names(["Avocado", "Beet"], res)
+          after_cursor = get_page_info(res, "startCursor")
+          before_cursor = get_page_info(res, "endCursor")
+
+          res = exec_query(query_str, after: after_cursor, before: before_cursor)
+          assert_equal true, get_page_info(res, "hasNextPage")
+          assert_equal true, get_page_info(res, "hasPreviousPage")
+          assert_names [], res
+        end
+
         it "handles out-of-bounds cursors" do
           # It treats negative cursors like zero
           bogus_negative_cursor = NonceEnabledEncoder.encode("-10")
@@ -300,7 +312,7 @@ def assert_names(expected_names, result)
           res = exec_query(query_str, {})
           # Neither first nor last was provided, so default_page_size was applied.
           assert_names(["Avocado", "Beet", "Cucumber", "Dill"], res)
-          assert_equal true, get_page_info(res, "hasNextPage")
+          assert_equal false, get_page_info(res, "hasNextPage")
           assert_equal false, get_page_info(res, "hasPreviousPage")
         end