Detect in-place changes on mutable AR attributes

We have several mutable types on Active Record now. (Serialized, JSON,
HStore). We need to be able to detect if these have been modified in
place.

3 files changed, 39 insertions, 1 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/hstore_test.rb b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
index a25c9cb5e4..83b495d600 100644
--- a/activerecord/test/cases/adapters/postgresql/hstore_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
@@ -163,6 +163,15 @@ class PostgresqlHstoreTest < ActiveRecord::TestCase
       assert_equal "GMT", y.timezone
     end
 
+    def test_changes_in_place
+      hstore = Hstore.create!(settings: { 'one' => 'two' })
+      hstore.settings['three'] = 'four'
+      hstore.save!
+      hstore.reload
+
+      assert_equal 'four', hstore.settings['three']
+    end
+
     def test_gen1
       assert_equal(%q(" "=>""), @column.class.hstore_to_string({' '=>''}))
     end
diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index 3ee8839823..a3400a5a19 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -165,4 +165,24 @@ class PostgresqlJSONTest < ActiveRecord::TestCase
     JsonDataType.update_all payload: { }
     assert_equal({ }, json.reload.payload)
   end
+
+  def test_changes_in_place
+    json = JsonDataType.new
+    assert_not json.changed?
+
+    json.payload = { 'one' => 'two' }
+    assert json.changed?
+    assert json.payload_changed?
+
+    json.save!
+    assert_not json.changed?
+
+    json.payload['three'] = 'four'
+    assert json.payload_changed?
+
+    json.save!
+    json.reload
+
+    assert json.payload['three'] = 'four'
+  end
 end
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index 87f24e32b2..5d6601a881 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -445,11 +445,20 @@ class DirtyTest < ActiveRecord::TestCase
   def test_save_should_store_serialized_attributes_even_with_partial_writes
     with_partial_writes(Topic) do
       topic = Topic.create!(:content => {:a => "a"})
+
+      assert_not topic.changed?
+
       topic.content[:b] = "b"
-      #assert topic.changed? # Known bug, will fail
+
+      assert topic.changed?
+
       topic.save!
+
+      assert_not topic.changed?
       assert_equal "b", topic.content[:b]
+
       topic.reload
+
       assert_equal "b", topic.content[:b]
     end
   end