ActiveRecordBatchEnumerator#each should rewind at the end

lib/job-iteration/active_record_batch_enumerator.rb

@@ -19,6 +19,7 @@ def initialize(relation, columns: nil, batch_size: 100, cursor: nil)
         @columns.dup << @primary_key
       end
       @cursor = Array.wrap(cursor)
+      @initial_cursor = @cursor
       raise ArgumentError, "Must specify at least one column" if @columns.empty?
       if relation.joins_values.present? && !@columns.all? { |column| column.to_s.include?(".") }
         raise ArgumentError, "You need to specify fully-qualified columns if you join a table"
@@ -56,7 +57,10 @@ def next_batch
       end
 
       cursor = cursor_values.last
-      return unless cursor.present?
+      unless cursor.present?
+        @cursor = @initial_cursor
+        return
+      end
       # The primary key was plucked, but original cursor did not include it, so we should remove it
       cursor.pop unless @primary_key_index
       @cursor = Array.wrap(cursor)

test/unit/active_record_batch_enumerator_test.rb

@@ -16,6 +16,12 @@ class ActiveRecordBatchEnumeratorTest < IterationUnitTest
       end
     end
 
+    test "#each yields relations repeatedly" do
+      enum = build_enumerator(cursor: 2)
+      assert_equal 4, enum.to_a.size
+      assert_equal 4, enum.to_a.size
+    end
+
     test "#each yields unloaded relations" do
       enum = build_enumerator
       relation, _ = enum.first