3 files changed, 25 insertions, 1 deletions
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 2ded97582d..e5022d49f1 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1579,7 +1579,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal [tagging], post.taggings
   end
 
-  def test_build_with_polymotphic_has_many_does_not_allow_to_override_type_and_id
+  def test_build_with_polymorphic_has_many_does_not_allow_to_override_type_and_id
     welcome = posts(:welcome)
     tagging = welcome.taggings.build(:taggable_id => 99, :taggable_type => 'ShouldNotChange')
 
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index d4fc5f204b..6fd9a9d11d 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -203,6 +203,20 @@ class DirtyTest < ActiveRecord::TestCase
     end
   end
 
+  def test_nullable_datetime_not_marked_as_changed_if_new_value_is_blank
+    in_time_zone 'Edinburgh' do
+      target = Class.new(ActiveRecord::Base)
+      target.table_name = 'topics'
+
+      topic = target.create
+      assert_equal nil, topic.written_on
+
+      topic.written_on = ""
+      assert_equal nil, topic.written_on
+      assert !topic.written_on_changed?
+    end
+  end
+
   def test_integer_zero_to_string_zero_not_marked_as_changed
     pirate = Pirate.new
     pirate.parrot_id = 0
diff --git a/activerecord/test/cases/explain_test.rb b/activerecord/test/cases/explain_test.rb
index 6dce8ccdd1..a7e5fdf709 100644
--- a/activerecord/test/cases/explain_test.rb
+++ b/activerecord/test/cases/explain_test.rb
@@ -108,6 +108,16 @@ if ActiveRecord::Base.connection.supports_explain?
       assert_equal expected, base.exec_explain(queries)
     end
 
+    def test_unsupported_connection_adapter
+      connection.stubs(:supports_explain?).returns(false)
+
+      base.logger.expects(:warn).never
+
+      with_threshold(0) do
+        Car.where(:name => 'honda').to_a
+      end
+    end
+
     def test_silence_auto_explain
       base.expects(:collecting_sqls_for_explain).never
       base.logger.expects(:warn).never