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.

1 files changed, 57 insertions, 0 deletions

diff --git a/activerecord/test/cases/ar_schema_test.rb b/activerecord/test/cases/ar_schema_test.rb
index 8700b20dee..3f5858714a 100644
--- a/activerecord/test/cases/ar_schema_test.rb
+++ b/activerecord/test/cases/ar_schema_test.rb
@@ -14,6 +14,7 @@ if ActiveRecord::Base.connection.supports_migrations?
       @connection.drop_table :fruits rescue nil
       @connection.drop_table :nep_fruits rescue nil
       @connection.drop_table :nep_schema_migrations rescue nil
+      @connection.drop_table :has_timestamps rescue nil
       ActiveRecord::SchemaMigration.delete_all rescue nil
     end
 
@@ -88,5 +89,61 @@ if ActiveRecord::Base.connection.supports_migrations?
       assert_equal "017", ActiveRecord::SchemaMigration.normalize_migration_number("0017")
       assert_equal "20131219224947", ActiveRecord::SchemaMigration.normalize_migration_number("20131219224947")
     end
+
+    def test_timestamps_without_null_is_deprecated_on_create_table
+      assert_deprecated do
+        ActiveRecord::Schema.define do
+          create_table :has_timestamps do |t|
+            t.timestamps
+          end
+        end
+      end
+    end
+
+    def test_timestamps_without_null_is_deprecated_on_change_table
+      assert_deprecated do
+        ActiveRecord::Schema.define do
+          create_table :has_timestamps
+
+          change_table :has_timestamps do |t|
+            t.timestamps
+          end
+        end
+      end
+    end
+
+    def test_no_deprecation_warning_from_timestamps_on_create_table
+      assert_not_deprecated do
+        ActiveRecord::Schema.define do
+          create_table :has_timestamps do |t|
+            t.timestamps null: true
+          end
+
+          drop_table :has_timestamps
+
+          create_table :has_timestamps do |t|
+            t.timestamps null: false
+          end
+        end
+      end
+    end
+
+    def test_no_deprecation_warning_from_timestamps_on_change_table
+      assert_not_deprecated do
+        ActiveRecord::Schema.define do
+          create_table :has_timestamps
+          change_table :has_timestamps do |t|
+            t.timestamps null: true
+          end
+
+          drop_table :has_timestamps
+
+          create_table :has_timestamps
+          change_table :has_timestamps do |t|
+            t.timestamps null: false, default: Time.now
+          end
+        end
+      end
+    end
   end
 end