babel-plugin-espower

babel-plugin-espower

Babel plugin for power-assert.

DESCRIPTION

babel-plugin-espower is a Babel plugin for power-assert.

power-assert provides descriptive assertion messages for your tests, like this.

  1) ES6 demo Destructuring and TemplateLiteral:

      AssertionError:   # test/demo_test.js:7

  assert(`${ alice.name } and ${ bob.name }` === `bob and alice`)
         |   |     |             |   |       |   |
         |   |     |             |   |       |   "bob and alice"
         |   |     |             |   "bob"   false
         |   |     "alice"       Object{name:"bob"}
         |   Object{name:"alice"}
         "alice and bob"

  --- [string] `bob and alice`
  +++ [string] `${ alice.name } and ${ bob.name }`
  @@ -1,13 +1,13 @@
  -bob and alice
  +alice and bob

Please note that babel-plugin-espower is an alpha version product. Pull-requests, issue reports and patches are always welcomed. See power-assert project for more documentation.

INSTALL

$ npm install --save-dev babel-core babel-plugin-espower
$ npm dedupe

HOW TO USE

via Babel CLI

$ ./node_modules/.bin/babel --plugins babel-plugin-espower /path/to/test/some_test.js > /path/to/build/some_test.js

or shortly,

$ ./node_modules/.bin/babel --plugins espower /path/to/test/some_test.js > /path/to/build/some_test.js

via Babel API

var babel = require('babel-core');
var jsCode = fs.readFileSync('/path/to/test/some_test.js');
var transformed = babel.transform(jsCode, {
    plugins: ['babel-plugin-espower']
});
console.log(transformed.code);

via Babel Require Hook

require('babel-core/register')({
    only: /test\/tobe_instrumented/,
    plugins: ['babel-plugin-espower'],
    extensions: ['.es6', '.js']
});

For example, with babel_hook.js above, you can run mocha without code generation steps.

$ ./node_modules/.bin/mocha --require ./babel_hook /path/to/test/demo_test.js

EXAMPLE

For given test file demo_test.js below,

import assert from 'power-assert';

describe('ES6 demo', () => {

    it('Destructuring and TemplateLiteral', () => {
        let [alice, bob] = [ { name: 'alice' }, { name: 'bob' } ];
        assert(`${alice.name} and ${bob.name}` === `bob and alice`);
    });

    it('ArrowFunctionExpression and SpreadElement', () => {
        let seven = 7, ary = [4, 5];
        assert(seven === ((v, i) => v + i)(...[...ary]));
    });

    it('Enhanced Object Literals', () => {
        let name = 'bobby';
        assert.deepEqual({
            name,
            [ `${name}'s greet` ]: `Hello, I'm ${name}`
        }, null);
    });

});

Run babel with --plugins espower to transform tests.

$ ./node_modules/.bin/babel --plugins espower /path/to/test/demo_test.js > /path/to/build/demo_test.js

Then run. You will see the power-assert output appears.

$ ./node_modules/.bin/mocha /path/to/build/demo_test.js

  ES6 demo
    1) Destructuring and TemplateLiteral
    2) ArrowFunctionExpression and SpreadElement
    3) Enhanced Object Literals


  0 passing
  3 failing

  1) ES6 demo Destructuring and TemplateLiteral:

      AssertionError:   # test/demo_test.js:7

  assert(`${ alice.name } and ${ bob.name }` === `bob and alice`)
         |   |     |             |   |       |   |
         |   |     |             |   |       |   "bob and alice"
         |   |     |             |   "bob"   false
         |   |     "alice"       Object{name:"bob"}
         |   Object{name:"alice"}
         "alice and bob"

  --- [string] `bob and alice`
  +++ [string] `${ alice.name } and ${ bob.name }`
  @@ -1,13 +1,13 @@
  -bob and alice
  +alice and bob

      at Context.<anonymous> (build/demo_test.js:19:28)

  2) ES6 demo ArrowFunctionExpression and SpreadElement:

      AssertionError:   # test/demo_test.js:12

  assert(seven === ((v, i) => v + i)(...[...ary]))
         |     |   |                    |   |
         |     |   |                    |   [4,5]
         |     |   9                    [4,5]
         7     false

  [number] ((v, i) => v + i)(...[...ary])
  => 9
  [number] seven
  => 7

      at Context.<anonymous> (build/demo_test.js:29:28)

  3) ES6 demo Enhanced Object Literals:
     AssertionError:   # test/demo_test.js:17

  assert.deepEqual({name,[`${ name }'s greet`]: `Hello, I'm ${ name }`}, null)
                   |      |   |                 |              |
                   |      |   |                 |              "bobby"
                   |      |   "bobby"           "Hello, I'm bobby"
                   |      "bobby's greet"
                   Object{name:"bobby","bobby's greet":"Hello, I'm bobby"}

      at Context.<anonymous> (build/demo_test.js:40:29)

CUSTOMIZE

You can customize assertion patterns via Babel API,

var babel = require('babel-core');
var createEspowerPlugin = require('babel-plugin-espower/create');
var jsCode = fs.readFileSync('/path/to/test/some_test.js');
var transformed = babel.transform(jsCode, {
    plugins: [
        createEspowerPlugin({
            patterns: [
                'assert.isNull(object, [message])',
                'assert.same(actual, expected, [message])',
                'assert.near(actual, expected, delta, [message])'
            ]
        })
    ]
});
console.log(transformed.code);

or via Require Hook.

var createEspowerPlugin = require('babel-plugin-espower/create');
require('babel-core/register')({
    only: /test\/tobe_instrumented/,
    plugins: [
        createEspowerPlugin({
            patterns: [
                'assert.isNull(object, [message])',
                'assert.same(actual, expected, [message])',
                'assert.near(actual, expected, delta, [message])'
            ]
        })
    ],
    extensions: ['.es6', '.js']
});

CHANGELOG

See CHANGELOG

AUTHOR

• Takuto Wada

LICENSE

Licensed under the MIT license.