GitLab

In tests for db indexes, when a test does op1; (merge2 x y); op3, the "repr" function used by op3 must be based on the repr given to op1 but with additionally redirecting x → y (as per the "merge") on the result of that repr. This applies to all db_index_… tests, including the "Invariant" test in db_index_tests.ml

let repr1 = function
  x when Var.equal x a -> a
  x when Var.equal x b -> a
  x when Var.equal x c -> d
  x when Var.equal x d -> d
  x -> x

let compose_repr f g x = f (g x)

repr_after_merge = compose @@ function
  x when Var.equal x a -> e
  x when Var.equal x e -> e
  x -> x

(* the result is the repr a->e b->e c->d d->d e->e anything_else->unchanged *)