2 files changed, 61 insertions, 0 deletions
diff --git a/activerecord/test/cases/relation/where_clause_test.rb b/activerecord/test/cases/relation/where_clause_test.rb
index f3a81f3c70..e5eb159d36 100644
--- a/activerecord/test/cases/relation/where_clause_test.rb
+++ b/activerecord/test/cases/relation/where_clause_test.rb
@@ -181,6 +181,53 @@ class ActiveRecord::Relation
       assert_equal WhereClause.empty, WhereClause.empty.or(where_clause)
     end
 
+    test "or places common conditions before the OR" do
+      a = WhereClause.new(
+        [table["id"].eq(bind_param(1)), table["name"].eq(bind_param("Sean"))],
+      )
+      b = WhereClause.new(
+        [table["id"].eq(bind_param(1)), table["hair_color"].eq(bind_param("black"))],
+      )
+
+      common = WhereClause.new(
+        [table["id"].eq(bind_param(1))],
+      )
+
+      or_clause = WhereClause.new([table["name"].eq(bind_param("Sean"))])
+        .or(WhereClause.new([table["hair_color"].eq(bind_param("black"))]))
+
+      assert_equal common + or_clause, a.or(b)
+    end
+
+    test "or can detect identical or as being a common condition" do
+      common_or = WhereClause.new([table["name"].eq(bind_param("Sean"))])
+        .or(WhereClause.new([table["hair_color"].eq(bind_param("black"))]))
+
+      a = common_or + WhereClause.new([table["id"].eq(bind_param(1))])
+      b = common_or + WhereClause.new([table["foo"].eq(bind_param("bar"))])
+
+      new_or = WhereClause.new([table["id"].eq(bind_param(1))])
+        .or(WhereClause.new([table["foo"].eq(bind_param("bar"))]))
+
+      assert_equal common_or + new_or, a.or(b)
+    end
+
+    test "or will use only common conditions if one side only has common conditions" do
+      only_common = WhereClause.new([
+        table["id"].eq(bind_param(1)),
+        "foo = bar",
+      ])
+
+      common_with_extra = WhereClause.new([
+        table["id"].eq(bind_param(1)),
+        "foo = bar",
+        table["extra"].eq(bind_param("pluto")),
+      ])
+
+      assert_equal only_common, only_common.or(common_with_extra)
+      assert_equal only_common, common_with_extra.or(only_common)
+    end
+
     private
 
       def table
diff --git a/activerecord/test/cases/relation/where_test.rb b/activerecord/test/cases/relation/where_test.rb
index c45fd38bc9..2fe2a67b1c 100644
--- a/activerecord/test/cases/relation/where_test.rb
+++ b/activerecord/test/cases/relation/where_test.rb
@@ -295,6 +295,20 @@ module ActiveRecord
       assert_equal essays(:david_modest_proposal), essay
     end
 
+    def test_where_with_relation_on_has_many_association
+      essay = essays(:david_modest_proposal)
+      author = Author.where(essays: Essay.where(id: essay.id)).first
+
+      assert_equal authors(:david), author
+    end
+
+    def test_where_with_relation_on_has_one_association
+      author = authors(:david)
+      author_address = AuthorAddress.where(author: Author.where(id: author.id)).first
+      assert_equal author_addresses(:david_address), author_address
+    end
+
+
     def test_where_on_association_with_select_relation
       essay = Essay.where(author: Author.where(name: "David").select(:name)).take
       assert_equal essays(:david_modest_proposal), essay