Fix an edge case with find with a list of ids, limit, and offset. Closes #8437.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6912 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 13 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 54f3a8252d..b838b1cdc0 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1032,16 +1032,18 @@ module ActiveRecord #:nodoc:
 
           result = find_every(options)
 
-          # If the user passes in a limit to find(), we need to check
-          # to see if the result is limited before just checking the
-          # size of the results.
+          # Determine expected size from limit and offset, not just ids.size.
           expected_size =
             if options[:limit] && ids.size > options[:limit]
               options[:limit]
             else
               ids.size
             end
-          expected_size -= options[:offset] if options[:offset]
+
+          # 11 ids with limit 3, offset 9 should give 2 results.
+          if options[:offset] && (ids.size - options[:offset] < expected_size)
+            expected_size = ids.size - options[:offset]
+          end
 
           if result.size == expected_size
             result
diff --git a/activerecord/test/finder_test.rb b/activerecord/test/finder_test.rb
index de7d1b4318..38838cab83 100644
--- a/activerecord/test/finder_test.rb
+++ b/activerecord/test/finder_test.rb
@@ -44,6 +44,13 @@ class FinderTest < Test::Unit::TestCase
   def test_find_by_ids_with_limit_and_offset
     assert_equal 2, Entrant.find([1,3,2], :limit => 2).size
     assert_equal 1, Entrant.find([1,3,2], :limit => 3, :offset => 2).size
+
+    # Also test an edge case: If you have 11 results, and you set a
+    #   limit of 3 and offset of 9, then you should find that there
+    #   will be only 2 results, regardless of the limit.
+    devs = Developer.find :all
+    last_devs = Developer.find devs.map(&:id), :limit => 3, :offset => 9
+    assert_equal 2, last_devs.size
   end
 
   def test_find_an_empty_array