Thus far, tests of General Relativity on cosmological distance scales have always lagged behind small-scale probes in precision. This situation has been further hindered by the rapid proliferation of alternative gravity theories; currently we have very little indication which, if any, of these should be considered frontrunners.
I'll introduce both the space of gravity theories and space of gravitational tests currently before us, highlighting the different questions asked by the cosmological and strong-field communities. I'll explain how, following recent progress in constructing model-independent frameworks for describing deviations from GR, we are finally in a good position to place sensible, agnostic constraints on alternative gravities.
I'll indicate how the next generation of large experiments — in particular, the LSST in combination with intensity mapping surveys — are expected to place cosmological tests of gravity on a roughly equal footing with small-scale probes.