The first stage of the Saturn I was tested three times using dummy upper stages filled with ballast water, see Project Highwater and this question. The first two flight tests of the Saturn V (SA-501 and SA-502, Apollo 4 and 6) were done with all three stages fuelled. See also Saturn I and Saturn V
Are there other rockets with two or more stages that have been flight tested using a first stage with dummy upper stages at first?