The book "Tests and Proofs" documents the refereed contributions of the 9th International Conference on Tests and Proofs, which took place in July 2015 in L'Aquila, Italy. It includes 11 revised full papers and 1 short contribution, carefully selected from a total of 21 submissions. The accepted works cover a wide range of testing techniques, including model-based, property-based, and grammar-based approaches, as well as methods for debugging and model-driven engineering. Additionally, topics such as model coverage, consistency, and validation are addressed. Many of the contributions utilize interactive and automated theorem provers, including SMT solvers and model checkers, to support the concepts presented.