1 files changed, 10 insertions, 0 deletions
diff --git a/activerecord/test/cases/associations/left_outer_join_association_test.rb b/activerecord/test/cases/associations/left_outer_join_association_test.rb
index 0e54e8c1b0..0a8863c35d 100644
--- a/activerecord/test/cases/associations/left_outer_join_association_test.rb
+++ b/activerecord/test/cases/associations/left_outer_join_association_test.rb
@@ -46,6 +46,12 @@ class LeftOuterJoinAssociationTest < ActiveRecord::TestCase
     assert queries.any? { |sql| /LEFT OUTER JOIN/i.match?(sql) }
   end
 
+  def test_left_outer_joins_is_deduped_when_same_association_is_joined
+    queries = capture_sql { Author.joins(:posts).left_outer_joins(:posts).to_a }
+    assert queries.any? { |sql| /INNER JOIN/i.match?(sql) }
+    assert queries.none? { |sql| /LEFT OUTER JOIN/i.match?(sql) }
+  end
+
   def test_construct_finder_sql_ignores_empty_left_outer_joins_hash
     queries = capture_sql { Author.left_outer_joins({}).to_a }
     assert queries.none? { |sql| /LEFT OUTER JOIN/i.match?(sql) }
@@ -60,6 +66,10 @@ class LeftOuterJoinAssociationTest < ActiveRecord::TestCase
     assert_raise(ArgumentError) { Author.left_outer_joins('LEFT OUTER JOIN "posts" ON "posts"."user_id" = "users"."id"').to_a }
   end
 
+  def test_left_outer_joins_with_string_join
+    assert_equal 16, Author.left_outer_joins(:posts).joins("LEFT OUTER JOIN comments ON comments.post_id = posts.id").count
+  end
+
   def test_join_conditions_added_to_join_clause
     queries = capture_sql { Author.left_outer_joins(:essays).to_a }
     assert queries.any? { |sql| /writer_type.*?=.*?(Author|\?|\$1|\:a1)/i.match?(sql) }