IDEA (International Detector for Electron-positron Accelerators) is a detector concept designed for a future leptonic collider operating as a Higgs factory. It is based on innovative detector technologies developed over years of R&D. In September 2018, prototypes of the proposed subdetectors have been tested for the first time on a beam line at CERN, setting a milestone for the detector design and test for future Higgs boson factory collider machines, like FCC-ee or CepC. The preliminary results from this test of a full slice of the IDEA detector will be presented. The talk will include results of standalone subdetector measurements and on their combined performance.