https://github.com/erdos/erdos.assert
power assert macro for clojure
https://github.com/erdos/erdos.assert
assertions clojure clojure-library power-assert
Last synced: 21 days ago
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power assert macro for clojure
- Host: GitHub
- URL: https://github.com/erdos/erdos.assert
- Owner: erdos
- License: epl-1.0
- Created: 2017-04-19T15:31:56.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2021-02-23T07:51:02.000Z (about 5 years ago)
- Last Synced: 2025-10-21T22:49:49.492Z (5 months ago)
- Topics: assertions, clojure, clojure-library, power-assert
- Language: Clojure
- Homepage:
- Size: 101 KB
- Stars: 85
- Watchers: 3
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Power Assertion macro for Clojure
The [Power Assertions](http://groovy-lang.org/testing.html#_power_assertions) feature in the Groovy language is a strong tool, it makes writing tests and finding bugs easier. This is an implementation for the Clojure programming language with support for macros and lazy sequences.
It prints subexpressions on assert failure.
And each evaluations of subexpressions are shown.
[](https://clojars.org/io.github.erdos/erdos.assert)
[](https://www.eclipse.org/legal/epl-1.0/)
[](https://github.com/erdos/erdos.assert/issues)
[](http://hits.dwyl.io/erdos/erdosassert)
## Usage
This library provides five small macros for easier debugging.
- The `examine` macro can be used to trace parts of an evaluated expression. Debug information is printed to the standard output and the value of the expression is returned.
- The `assert` macro is similar to `clojure.core/assert`. It wraps the examined information in the thrown `AssertionError` instance.
- The `verify` macro is just like `assert`, but it throws an `ExceptionInfo` instead.
- The `is` and `are` macros are drop-in replacements for `clojure.test/is` and `clojure.test/are` used in unit tests.
**First**, add the dependency to your `project.clj`.
```clojure
[io.github.erdos/erdos.assert "0.2.3"]
```
**Second**, require the namespace:
```clojure
(require '[erdos.assert :as ea])
```
In the REPL, **examining** simple expressions will print to `*out*`.
```clojure
erdos.assert=> (examine (* (+ 19 17) (- 19 17)))
(* (+ 19 17) (- 19 17))
¦ ¦ ¦
72 36 2
```
You can also write **assertions** that will wrap examined data as a string in the `AssertionError` instance.
```clojure
erdos.assert=> (assert (= 1 (* 3 (/ 1 3)) "") ; does not print anything
erdos.assert=> (assert (= (* 1.0 1) (* 3 (/ 1 3))) "")
; AssertionError
; (= (* 1.0 1) (* 3 (/ 1 3)))
; ¦ ¦ ¦ ¦
; ¦ 1.0 1N 1/3
; false
```
Shown output is arranged to make place for more complex output.
```clojure
erdos.assert=> (examine (+ (* 12 (- 32 12) 12.2) (- 3 (/ 1 2 3 4) 2.2) (* (- 1 2) 3)))
(+ (* 12 (- 32 12) 12.2) (- 3 (/ 1 2 3 4) 2.2) (* (- 1 2) 3))
¦ ¦ ¦ ¦ ¦ ¦ ¦
¦ ¦ 20 ¦ 1/24 -3 -1
¦ 2928.0 0.7583333333333329
2925.758333333333
```
Some expressions are evaluated repeatedly, hence all values are shown.
```clojure
erdos.assert=> (examine (dotimes [i 5] (print (* i i))))
(dotimes [i 5] (print (* i i)))
¦ ¦
¦ 16, 9, 4, 1, 0
nil, nil, nil, nil, nil
```
Only the already realized part is printed for lazy sequences.
```clojure
erdos.assert=> (examine (reduce + (map * (range) (range 0 10 2))))
(reduce + (map * (range) (range 0 10 2)))
¦ ¦ ¦ ¦
60 (…) (0 …) (0 2 4 6 8)
```
In such cases you might want to run [doall](https://clojuredocs.org/clojure.core/doall) on intermediate lazy sequences.
```clojure
erdos.assert=> (examine (reduce + (doall (map * (range) (range 0 10 2)))))
(reduce + (doall (map * (range) (range 0 10 2))))
¦ ¦ ¦ ¦ ¦
60 ¦ (…) (0 …) (0 2 4 6 8)
(0 2 8 18 32)
```
Add the `^:show` metadata to function arguments to show the values on every function invocation:
```clojure
erdos.assert=> (examine (mapv (fn [^:show a] (mod a 3)) (range 10)))
(mapv (fn [a] (mod a 3)) (range 10))
¦ ¦ ¦ ¦
¦ ¦ ¦ (0 1 2 3 4 5 6 7 8 9)
¦ ¦ 0, 1, 2, 0, 1, 2, 0, 1, 2, 0
¦ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
[0 1 2 0 1 2 0 1 2 0]
```
## License
Copyright © 2017-2021 Janos Erdos
Distributed under the [Eclipse Public License version 1.0](https://www.eclipse.org/legal/epl-1.0/).