  The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute
between 2010 and 2014, serving as a pilot plant and testbed for the development
and realization of SwissFEL, the X-ray Free-Electron Laser facility under
construction at the same institute. The test facility consisted of a
laser-driven rf electron gun followed by an S-band booster linac, a magnetic
bunch compression chicane and a diagnostic section including a transverse
deflecting rf cavity. It delivered electron bunches of up to 200 pC charge and
up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements
performed at the test facility not only demonstrated the beam parameters
required to drive the first stage of an FEL facility, but also led to
significant advances in instrumentation technologies, beam characterization
methods and the generation, transport and compression of ultra-low-emittance
beams. We give a comprehensive overview of the commissioning experience of the
principal subsystems and the beam physics measurements performed during the
operation of the test facility, including the results of the test of an
in-vacuum undulator prototype generating radiation in the vacuum ultraviolet
and optical range.
