macropreviously cljs.spec.test/instrumentEdit
(instrument xs)
(instrument sym-or-syms opts)

Source docstring:
Instruments the vars named by sym-or-syms, a symbol or collection
of symbols, or all instrumentable vars if sym-or-syms is not
specified. If a symbol identifies a namespace then all symbols in that
namespace will be enumerated.

If a var has an :args fn-spec, sets the var's root binding to a
fn that checks arg conformance (throwing an exception on failure)
before delegating to the original fn.

The opts map can be used to override registered specs, and/or to
replace fn implementations entirely. Opts for symbols not included
in sym-or-syms are ignored. This facilitates sharing a common
options map across many different calls to instrument.

The opts map may have the following keys:

  :spec     a map from var-name symbols to override specs
  :stub     a set of var-name symbols to be replaced by stubs
  :gen      a map from spec names to generator overrides
  :replace  a map from var-name symbols to replacement fns

:spec overrides registered fn-specs with specs your provide. Use
:spec overrides to provide specs for libraries that do not have
them, or to constrain your own use of a fn to a subset of its
spec'ed contract.

:stub replaces a fn with a stub that checks :args, then uses the
:ret spec to generate a return value.

:gen overrides are used only for :stub generation.

:replace replaces a fn with a fn that checks args conformance, then
invokes the fn you provide, enabling arbitrary stubbing and mocking.

:spec can be used in combination with :stub or :replace.

Returns a collection of syms naming the vars instrumented.
Source code @ clojurescript:src/main/cljs/cljs/spec/test/alpha.cljc
(defmacro instrument
   `(instrument '[~@(#?(:clj  s/speced-vars
                        :cljs cljs.spec.alpha$macros/speced-vars))]))
   `(instrument ~xs nil))
  ([sym-or-syms opts]
   (let [syms (sym-or-syms->syms (eval sym-or-syms))
         opts-sym (gensym "opts")]
     `(let [~opts-sym ~opts]
          (fn [ret# [_# f#]]
            (let [sym# (f#)]
              (cond-> ret# sym# (conj sym#))))
          (->> (zipmap '~syms
                      (fn [sym]
                        `(fn [] (instrument-1 '~sym ~opts-sym)))
            (filter #((instrumentable-syms ~opts-sym) (first %)))
            (distinct-by first)))))))