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babel-plugin-unassert
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Babel plugin for unassert: Encourages programming with assertions by providing tools to compile them away.
babel-plugin-unassert removes assertions on build. So you can use assertions to declare preconditions, postconditions and invariants.
$ npm install --save-dev babel-plugin-unassert
Babel7 is incompatible with Babel6. Babel6 is incompatible with Babel5.
For Babel6, you need to use the 2.x release of babel-plugin-unassert.
$ npm install --save-dev babel-plugin-unassert@2
For Babel 5 or lower, you need to use the 1.x release of babel-plugin-unassert.
$ npm install --save-dev babel-plugin-unassert@1
const presets = ['@babel/env'];
const plugins = [];
if (process.env.NODE_ENV === 'production') {
plugins.push('babel-plugin-unassert');
}
module.exports = { presets, plugins };
$ babel /path/to/src/target.js > /path/to/build/target.js
$ babel --plugins babel-plugin-unassert /path/to/src/target.js > /path/to/build/target.js
const babel = require('@babel/core');
const transformed = babel.transformFileSync('/path/to/src/target.js', {
presets: ['@babel/env'],
plugins: ['babel-plugin-unassert']
});
console.log(transformed.code);
For given math.js
below,
'use strict';
const 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;
}
Run babel-cli
with --plugins babel-plugin-unassert
option to transform.
$ babel --plugins babel-plugin-unassert /path/to/demo/math.js > /path/to/build/math.js
You will see assert calls and declarations disappear.
'use strict';
function add(a, b) {
return a + b;
}
babel-plugin-unassert supports ES6 module syntax and power-assert.
For given babel.config.js,
module.exports = function (api) {
const presets = ['@babel/env'];
const plugins = [];
if (api.env(['development', 'test'])) {
presets.push('babel-preset-power-assert');
}
if (api.env('production')) {
plugins.push('babel-plugin-unassert');
}
return {
presets,
plugins
};
};
and production code below,
import assert from 'assert';
class Calc {
add (a, b) {
assert(!(isNaN(a) || isNaN(b)));
assert(typeof a === 'number');
assert(typeof b === 'number');
return a + b;
}
}
then it becomes in production,
'use strict';
class Calc {
add(a, b) {
return a + b;
}
}
and in development, produces power-assert messages like below
AssertionError: # example.js:5
assert(!(isNaN(a) || isNaN(b)))
| | | | | |
| | | | true NaN
| false 3 true
false
Assertion expressions are removed when they match patterns below. In other words, babel-plugin-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([message])
assert.fail(actual, expected, message, operator)
assert.throws(block, [error], [message])
assert.doesNotThrow(block, [message])
assert.rejects(asyncFn, [error], [message])
assert.doesNotReject(asyncFn, [error], [message])
assert.ifError(value)
console.assert(value, [message])
babel-plugin-unassert also removes assert variable declarations such as,
const assert = require("assert")
const assert = require("node:assert")
const assert = require("assert").strict
const assert = require("node:assert").strict
const assert = require("power-assert")
const assert = require("power-assert").strict
import assert from "assert"
import assert from "node:assert"
import assert from "power-assert"
import * as assert from "assert"
import * as assert from "node:assert"
import * as assert from "power-assert"
import {strict as assert} from "assert"
import {strict as assert} from "node:assert"
import {strict as assert} from "power-assert"
and assignments.
assert = require("assert")
assert = require("node:assert")
assert = require("assert").strict
assert = require("node:assert").strict
assert = require("power-assert")
assert = require("power-assert").strict
You can customize Plugin Options such as assertion patterns.
input:
'use strict';
var invariant = require('invariant');
const nassert = require('nanoassert');
import * as uassert from 'uvu/assert';
function add (a, b) {
nassert(!isNaN(a));
uassert.is(Math.sqrt(4), 2);
uassert.is(Math.sqrt(144), 12);
uassert.is(Math.sqrt(2), Math.SQRT2);
invariant(someTruthyVal, 'This will not throw');
invariant(someFalseyVal, 'This will throw an error with this message');
return a + b;
}
output:
'use strict';
function add(a, b) {
return a + b;
}
via Config Files
{
"presets": [
...
],
"plugins": [
["babel-plugin-unassert", {
"variables": [
"assert",
"invariant",
"nassert",
"uassert"
],
"modules": [
"assert",
"node:assert",
"invariant",
"nanoassert",
"uvu/assert"
]
}]
]
}
or via @babel/register.
require('@babel/register')({
presets: [...],
plugins: [
['babel-plugin-unassert', {
variables: [
'assert',
'invariant',
'nassert',
'uassert'
],
modules: [
'assert',
'node:assert',
'invariant',
'nanoassert',
'uvu/assert'
]
}]
]
});
or via '@babel/core',
const babel = require('@babel/core');
const jsCode = fs.readFileSync('/path/to/test/some_test.js');
const transformed = babel.transform(jsCode, {
presets: [...],
plugins: [
['babel-plugin-unassert', {
variables: [
'assert',
'invariant',
'nassert',
'uassert'
],
modules: [
'assert',
'node:assert',
'invariant',
'nanoassert',
'uvu/assert'
]
}]
]
});
console.log(transformed.code);
type | default value |
---|---|
object | objects shown below |
Configuration options for babel-plugin-unassert
. If not passed, default options will be used.
{
variables: [
'assert'
],
modules: [
'assert',
'power-assert',
'node:assert'
]
}
We support Node under maintenance. In other words, we stop supporting old Node version when their maintenance ends.
This means that any other environment is not supported.
NOTE: If babel-plugin-unassert works in any of the unsupported environments, it is purely coincidental and has no bearing on future compatibility. Use at your own risk.
Licensed under the MIT license.
FAQs
Babel plugin for unassert: Encourages programming with assertions by providing tools to compile them away
The npm package babel-plugin-unassert receives a total of 3,641 weekly downloads. As such, babel-plugin-unassert popularity was classified as popular.
We found that babel-plugin-unassert demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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