A method of pressure testing a lower marine riser package includes forming an inflatable packer having exposed slats and an inflatable packer element. The packer is positioned within the lower marine riser package above the cap seal with the exposed slats above the packer element. The packer is inflated and fluid pressure is then applied to test the integrity of the cap seal. The packer may be inverted, then positioned below the BOP/riser connection, the packer inflated, and pressure increased above the inflated packer element to test the fluid integrity of the BOP/riser connection.