Merge pull request rails#41324 from eileencodes/fix-timestamp-type-for-sqlite3

Fix timestamp type for sqlite3

Author: eileencodes

activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb

@@ -71,6 +71,10 @@ def #{option_name}=(value)
           end
         CODE
       end
+
+      def aliased_types(name, fallback)
+        "timestamp" == name ? :datetime : fallback
+      end
     end
 
     AddColumnDefinition = Struct.new(:column) # :nodoc:

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -271,7 +271,7 @@ def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
       def change_column(table_name, column_name, type, **options) #:nodoc:
         alter_table(table_name) do |definition|
           definition[column_name].instance_eval do
-            self.type = type
+            self.type = aliased_types(type.to_s, type)
             self.options.merge!(options)
           end
         end

activerecord/test/cases/migration/change_schema_test.rb

@@ -290,6 +290,28 @@ def test_add_column_with_timestamp_type
         end
       end
 
+      def test_change_column_with_timestamp_type
+        connection.create_table :testings do |t|
+          t.column :foo, :datetime, null: false
+        end
+
+        connection.change_column :testings, :foo, :timestamp
+
+        column = connection.columns(:testings).find { |c| c.name == "foo" }
+
+        assert_equal :datetime, column.type
+
+        if current_adapter?(:PostgreSQLAdapter)
+          assert_equal "timestamp without time zone", column.sql_type
+        elsif current_adapter?(:Mysql2Adapter)
+          assert_equal "timestamp", column.sql_type
+        elsif current_adapter?(:OracleAdapter)
+          assert_equal "TIMESTAMP(6)", column.sql_type
+        else
+          assert_equal connection.type_to_sql("datetime"), column.sql_type
+        end
+      end
+
       def test_change_column_quotes_column_names
         connection.create_table :testings do |t|
           t.column :select, :string