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Macros for runtime assertion in Clojure(Script).

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Runtime asserts with better reporting about failed asserting value.


  • Ex-data with info about failed asserting value.
  • Predicate based assertions.
  • Return true instead of nil to be used directly in :pre/:post conditions.
  • Argument order is designed to be used with doto macro.
  • Exception-inherited exceptions instead of Throwable-inherited ones.



Main macro to assert value/expression by predicate function.

(ns readme.api-01-assert-pred
  (:require [strojure.assertie.core :as a :include-macros true]))

(a/assert-pred "1" string?)
;=> true

(a/assert-pred (inc 0) string?)
;Assert failed: (assert-pred (inc 0) string?)
; #:asserting{:value 1, :type java.lang.Long}

(a/assert-pred (inc 0) string? "Expect string")
;Expect string - Assert failed: (assert-pred (inc 0) string?)
; #:asserting{:value 1, :type java.lang.Long}

(a/assert-pred [] (a/not-thrown first))
;=> true

(a/assert-pred 1 (a/not-thrown first))
;Assert failed: (assert-pred 1 (a/not-thrown first))
; #:asserting{:value 1, :type java.lang.Long}
;Don't know how to create ISeq from: java.lang.Long


Secondary macro similar to clojure.core/assert.

(ns readme.api-02-assert-expr
  (:require [strojure.assertie.core :as a :include-macros true]))

(a/assert-expr (= 1 (inc 0)))
;=> true

(a/assert-expr (= 1 2))
;Assert failed: (assert-expr (= 1 2))
; #:asserting{:value false}

(a/assert-expr (= 1 2) "Expect 1=2")
;Expect 1=2 - Assert failed: (assert-expr (= 1 2))
; #:asserting{:value false}


Custom macro to assert against spec. This macro is an example of implementation of new macros on top of assertie.

(ns readme.api-03-assert-spec
  (:require [clojure.spec.alpha :as s]
            [strojure.assertie.spec-alpha :as a :include-macros true]))

(s/def ::string string?)

(a/assert-spec "1" ::string "Message")
;=> true

(a/assert-spec 1 ::string "Message")
;Message - Assert failed: (assert-spec 1 :project.readme.example.spec-01-assert-spec/string)
; {}
;Spec assertion failed
;1 - failed: string?
; #:clojure.spec.alpha{:problems [{:path [], :pred clojure.core/string?, :val 1, :via [], :in []}], :spec :project.readme.example.spec-01-assert-spec/string, :value 1, :failure :assertion-failed}

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