1 files changed, 91 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
new file mode 100644
index 0000000000..0e54e8c1b0
--- /dev/null
+++ b/activerecord/test/cases/associations/left_outer_join_association_test.rb
@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/post"
+require "models/comment"
+require "models/author"
+require "models/essay"
+require "models/category"
+require "models/categorization"
+require "models/person"
+
+class LeftOuterJoinAssociationTest < ActiveRecord::TestCase
+  fixtures :authors, :author_addresses, :essays, :posts, :comments, :categorizations, :people
+
+  def test_construct_finder_sql_applies_aliases_tables_on_association_conditions
+    result = Author.left_outer_joins(:thinking_posts, :welcome_posts).to_a
+    assert_equal authors(:david), result.first
+  end
+
+  def test_construct_finder_sql_does_not_table_name_collide_on_duplicate_associations
+    assert_nothing_raised do
+      queries = capture_sql do
+        Person.left_outer_joins(agents: { agents: :agents })
+              .left_outer_joins(agents: { agents: { primary_contact: :agents } }).to_a
+      end
+      assert queries.any? { |sql| /agents_people_4/i.match?(sql) }
+    end
+  end
+
+  def test_left_outer_joins_count_is_same_as_size_of_loaded_results
+    assert_equal 17, Post.left_outer_joins(:comments).to_a.size
+    assert_equal 17, Post.left_outer_joins(:comments).count
+  end
+
+  def test_left_joins_aliases_left_outer_joins
+    assert_equal Post.left_outer_joins(:comments).to_sql, Post.left_joins(:comments).to_sql
+  end
+
+  def test_left_outer_joins_return_has_value_for_every_comment
+    all_post_ids = Post.pluck(:id)
+    assert_equal all_post_ids, all_post_ids & Post.left_outer_joins(:comments).pluck(:id)
+  end
+
+  def test_left_outer_joins_actually_does_a_left_outer_join
+    queries = capture_sql { Author.left_outer_joins(:posts).to_a }
+    assert queries.any? { |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) }
+  end
+
+  def test_construct_finder_sql_ignores_empty_left_outer_joins_array
+    queries = capture_sql { Author.left_outer_joins([]).to_a }
+    assert queries.none? { |sql| /LEFT OUTER JOIN/i.match?(sql) }
+  end
+
+  def test_left_outer_joins_forbids_to_use_string_as_argument
+    assert_raise(ArgumentError) { Author.left_outer_joins('LEFT OUTER JOIN "posts" ON "posts"."user_id" = "users"."id"').to_a }
+  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) }
+    assert queries.none? { |sql| /WHERE/i.match?(sql) }
+  end
+
+  def test_find_with_sti_join
+    scope = Post.left_outer_joins(:special_comments).where(id: posts(:sti_comments).id)
+
+    # The join should match SpecialComment and its subclasses only
+    assert_empty scope.where("comments.type" => "Comment")
+    assert_not_empty scope.where("comments.type" => "SpecialComment")
+    assert_not_empty scope.where("comments.type" => "SubSpecialComment")
+  end
+
+  def test_does_not_override_select
+    authors = Author.select("authors.name, #{%{(authors.author_address_id || ' ' || authors.author_address_extra_id) as addr_id}}").left_outer_joins(:posts)
+    assert_predicate authors, :any?
+    assert_respond_to authors.first, :addr_id
+  end
+
+  test "the default scope of the target is applied when joining associations" do
+    author = Author.create! name: "Jon"
+    author.categorizations.create!
+    author.categorizations.create! special: true
+
+    assert_equal [author], Author.where(id: author).left_outer_joins(:special_categorizations)
+  end
+end