While General Relativity has withstood tests on solar system scales, progress in observational cosmology now enables tests on the largest scales. I will present the latest tests of gravity with stage-III surveys measurements of weak lensing and Cosmic Microwave Background (CMB). Such analyses are setting the scene for tests of fundamental physics with surveys of the next decade: I will present the Rubin Observatory, under construction in Chile and planned to start mapping the sky in 2025, and talk through the expected precision and challenges to test gravity with this transformative experiment.
