GetTables() (tableList []string, err error)
	TableType(dst interface{}) (TableType, error)

	// Columns
	AddColumn(dst interface{}, field string) error
	DropColumn(dst interface{}, field string) error
	AlterColumn(dst interface{}, field string) error
	MigrateColumn(dst interface{}, field *schema.Field, columnType ColumnType) error
	// MigrateColumnUnique migrate column's UNIQUE constraint, it's part of MigrateColumn.

	}
}

type CompanyNew struct {
	ID   int
	Name int
}

func TestAlterColumnDataType(t *testing.T) {
	DB.AutoMigrate(Company{})

	if err := DB.Table("companies").Migrator().AlterColumn(CompanyNew{}, "name"); err != nil {
		t.Fatalf("failed to alter column from string to int, got error %v", err)
	}

	DB.AutoMigrate(Company{})