espower

espower

Power Assert feature instrumentor based on the Mozilla JavaScript AST.

DESCRIPTION

espower is a core module of power-assert family.

espower detects and manipulates assertion expression (JavaScript Code) in original AST represented as Mozilla JavaScript AST, to instrument power-assert feature into returned new AST object. Mozilla JavaScript AST in, Mozilla JavaScript AST out.

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

CHANGELOG

See CHANGELOG

API

var modifiedAst = espower(originalAst, [options])

return type
object

espower function manipulates originalAst then returns modifiedAst that is also an AST node object defined in Mozilla JavaScript AST spec. If destructive option is falsy, originalAst will be unchanged. If destructive option is truthy, originalAst will be manipulated directly and returned modifiedAst will be the same instance of originalAst.

originalAst

type	default value
object	N/A

originalAst should be an AST node object defined in Mozilla JavaScript AST spec.

options

type	default value
object	(return value of espower.defaultOptions())

Configuration options. If not passed, default options will be used.

options.destructive

type	default value
boolean	false

Modify originalAst destructively or not.

If false, espower clones originalAst deeply, so originalAst will be unchanged. If true, originalAst will be manipulated directly and returned modifiedAst will be the same instance of originalAst.

options.patterns

type	default value
Array of string	objects shown below

[
    '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])'
]

Target patterns for power assert feature instrumentation.

If callee name (for example, assert.equal) matches exactly and number of arguments is satisfied, then the assertion will be modified. Detection is done by escallmatch. Any arguments enclosed in bracket (for example, [message]) means optional parameters. Without bracket means mandatory parameters.

(optional) options.path

type	default value
string	N/A

Filepath of originalAst. If passed, espower stores filepath information for reporting. This property is optional.

var options = espower.defaultOptions();

Returns default options object for espower function. In other words, returns

{
    destructive: false,
    patterns: [
        '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])'
    ]
}

EXAMPLE

For given test file example_test.js below,

var assert = require('power-assert'),
    truthy = 'true',
    falsy = 'false';
assert(falsy);
assert.equal(truthy, falsy);

Apply espower then generate modified code to console,

var espower = require('espower'),
    esprima = require('esprima'),
    escodegen = require('escodegen'),
    fs = require('fs'),
    path = require('path');

var filepath = path.join(__dirname, 'example_test.js');
var jsAst = esprima.parse(fs.readFileSync(filepath), {tolerant: true, loc: true, tokens: true});
var modifiedAst = espower(jsAst, {path: filepath});

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

Output:

var assert = require('power-assert'), truthy = 'true', falsy = 'false';
assert(assert._expr(assert._capt(falsy, 'arguments/0'), {
    content: 'assert(falsy)',
    filepath: '/path/to/example_test.js',
    line: 4
}));
assert.equal(assert._expr(assert._capt(truthy, 'arguments/0'), {
    content: 'assert.equal(truthy, falsy)',
    filepath: '/path/to/example_test.js',
    line: 5
}), assert._expr(assert._capt(falsy, 'arguments/1'), {
    content: 'assert.equal(truthy, falsy)',
    filepath: '/path/to/example_test.js',
    line: 5
}));

INSTALL

via npm

Install

$ npm install --save-dev espower

via bower

Install

$ bower install --save-dev espower

Then load (espower function is exported)

<script type="text/javascript" src="./path/to/bower_components/espower/build/espower.js"></script>

AUTHOR

• Takuto Wada

LICENSE

Licensed under the MIT license.

Changelog

0.8.0 (2014-08-12)

Features

• espower:
  • built and modularized by browserify
  • use escallmatch module to describe instrumentation target patterns
  • support chained callee like browser.assert.element(selector) (ea0a3ce9)

Breaking Changes

• option powerAssertVariableName is now deprecated and ignored. Please use patterns option instead (2f023f91)
• option targetMethods is now deprecated and ignored. Please use patterns option instead (e75e5d35)

If you already customize instrumentation pattern using powerAssertVariableName and targetMethods, you need to migarte. To migrate, change your code from the following:

var options = {
    powerAssertVariableName: 'yourAssert',
    targetMethods: {
        oneArg: [
            'okay'
        ],
        twoArgs: [
            'equal',
            'customEqual'
        ]
    }
};
var modifiedAst = espower(jsAst, options);

To:

var options = {
    patterns: [
        'yourAssert(value, [message])',
        'yourAssert.okay(value, [message])',
        'yourAssert.equal(actual, expected, [message])',
        'yourAssert.customEqual(actual, expected, [message])'
    ]
};
var modifiedAst = espower(jsAst, options);