Abstract: A soft package fabricated of a material with a memory is tested by placing the package in a vacuum. If there are no leaks in the package, the package undergoes a dimensional change as the vacuum is created. This dimensional change can be measured. If no dimensional changes occurs, the package has a gross leak. If the package increases in dimension and then gradually returns to its original shape, a slow leak exists. If the package grows in dimension upon creation of vacuum and retains that dimensional growth, there is no leak in the package. A test fixture for measuring the dimensional changes includes a base plate on which a package may be positioned. A support member is mounted on the base plate to support a plunger rod for reciprocal movement relative to the base plate. The plunger includes a first end that engages the package to be tested and a second end on which a platform is mounted. A counterweight is positioned onthe platform.