unassert

Encourage Design by Contract (DbC) by writing assertions in production code, and compiling them away from release.

RELATED MODULES

• unassertify: Browserify transform to remove assertions on build
• babel-plugin-unassert: Babel plugin to remove assertions on build
• webpack-unassert-loader: A webpack loader to remove assertions on production build

INSTALL

$ npm install --save-dev unassert

EXAMPLE

For given math.js below,

'use strict';

var assert = require('assert');

function add (a, b) {
    console.assert(typeof a === 'number');
    assert(!isNaN(a));
    assert.equal(typeof b, 'number');
    assert.ok(!isNaN(b));
    return a + b;
}

Apply unassert then generate modified code to console.

var esprima = require('esprima');
var escodegen = require('escodegen');
var unassert = require('unassert');
var fs = require('fs');
var path = require('path');
var filepath = path.join(__dirname, 'math.js');

var ast = esprima.parse(fs.readFileSync(filepath));
var modifiedAst = unassert(ast);

console.log(escodegen.generate(modifiedAst));

Then you will see assert calls disappear.

'use strict';
function add(a, b) {
    return a + b;
}

Note: unassert supports removal of power-assert declarations (var assert = require('power-assert');) too.

SUPPORTED PATTERNS

Assertion expressions are removed when they match patterns below. In other words, unassert removes assertion calls that are compatible with Node.js standard assert API (and console.assert).

• assert(value, [message])
• assert.ok(value, [message])
• assert.equal(actual, expected, [message])
• assert.notEqual(actual, expected, [message])
• assert.strictEqual(actual, expected, [message])
• assert.notStrictEqual(actual, expected, [message])
• assert.deepEqual(actual, expected, [message])
• assert.notDeepEqual(actual, expected, [message])
• assert.deepStrictEqual(actual, expected, [message])
• assert.notDeepStrictEqual(actual, expected, [message])
• assert.fail(actual, expected, message, operator)
• assert.throws(block, [error], [message])
• assert.doesNotThrow(block, [message])
• assert.ifError(value)
• console.assert(value, [message])

unassert also removes assert variable declarations,

• var assert = require("assert")
• var assert = require("power-assert")
• import assert from "assert"
• import assert from "power-assert"

and assignments.

• assert = require("assert")
• assert = require("power-assert")

AUTHOR

• Takuto Wada

LICENSE

Licensed under the MIT license.