Change the default `null` value for timestamps

As per discussion, this changes the model generators to specify
`null: false` for timestamp columns. A warning is now emitted if
`timestamps` is called without a `null` option specified, so we can
safely change the behavior when no option is specified in Rails 5.

3 files changed, 8 insertions, 5 deletions

diff --git a/activerecord/test/cases/migration/change_schema_test.rb b/activerecord/test/cases/migration/change_schema_test.rb
index c66eaf1ee1..bd3dd29f4d 100644
--- a/activerecord/test/cases/migration/change_schema_test.rb
+++ b/activerecord/test/cases/migration/change_schema_test.rb
@@ -176,8 +176,11 @@ module ActiveRecord
       end
 
       def test_create_table_with_timestamps_should_create_datetime_columns
-        connection.create_table table_name do |t|
-          t.timestamps
+        # FIXME: Remove the silence when we change the default `null` behavior
+        ActiveSupport::Deprecation.silence do
+          connection.create_table table_name do |t|
+            t.timestamps
+          end
         end
         created_columns = connection.columns(table_name)
 
diff --git a/activerecord/test/cases/migration/change_table_test.rb b/activerecord/test/cases/migration/change_table_test.rb
index 3e9d957ed3..777a48ad14 100644
--- a/activerecord/test/cases/migration/change_table_test.rb
+++ b/activerecord/test/cases/migration/change_table_test.rb
@@ -88,8 +88,8 @@ module ActiveRecord
 
       def test_timestamps_creates_updated_at_and_created_at
         with_change_table do |t|
-          @connection.expect :add_timestamps, nil, [:delete_me]
-          t.timestamps
+          @connection.expect :add_timestamps, nil, [:delete_me, null: true]
+          t.timestamps null: true
         end
       end
 
diff --git a/activerecord/test/cases/migration/helper.rb b/activerecord/test/cases/migration/helper.rb
index e28feedcf9..4dad77e8fd 100644
--- a/activerecord/test/cases/migration/helper.rb
+++ b/activerecord/test/cases/migration/helper.rb
@@ -22,7 +22,7 @@ module ActiveRecord
         super
         @connection = ActiveRecord::Base.connection
         connection.create_table :test_models do |t|
-          t.timestamps
+          t.timestamps null: true
         end
 
         TestModel.reset_column_information