Ordinal methods should respect loaded records

We should reset partially loaded `@offsets` cache when latest records
has loaded because the cache has been staled and it may not be
consistent with latest records.

2 files changed, 17 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 997cfe4b5e..c16d89aa00 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -594,6 +594,7 @@ module ActiveRecord
           end
 
           @records.each(&:readonly!) if readonly_value
+          @offsets = {} unless @offsets.empty?
 
           @loaded = true
           @records
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index d8bc917e7f..d03af7f111 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -676,6 +676,22 @@ class FinderTest < ActiveRecord::TestCase
     assert_kind_of Array, Topic.last(5)
   end
 
+  def test_first_should_respect_loaded_records
+    authors = Author.order(:name)
+
+    assert_equal authors(:bob), authors.first
+
+    aaron = authors.create!(name: "Aaron")
+
+    authors.load
+
+    assert_no_queries do
+      assert_equal aaron, authors.first
+      assert_equal authors(:bob), authors.second
+      assert_not_equal authors.first, authors.second
+    end
+  end
+
   def test_unexisting_record_exception_handling
     assert_raise(ActiveRecord::RecordNotFound) {
       Topic.find(1).parent