cljs.spec.alpha/assert

macropreviously cljs.spec/assertEdit
(assert spec x)

Source docstring:
spec-checking assert expression. Returns x if x is valid? according
to spec, else throws an error with explain-data plus ::failure of
:assertion-failed.
Can be disabled at either compile time or runtime:
If *compile-asserts* is false at compile time, compiles to x. Defaults
to the negation value of the ':elide-asserts' compiler option, or true if
not set.
If (check-asserts?) is false at runtime, always returns x. Defaults to
value of 'cljs.spec.alpha/*runtime-asserts*', or false if not set. You can
toggle check-asserts? with (check-asserts bool).
Source code @ clojurescript:src/main/cljs/cljs/spec/alpha.cljc
(defmacro assert
  [spec x]
  `(if *compile-asserts*
     (if *runtime-asserts*
       (assert* ~spec ~x)
       ~x)
    ~x))