espower

Power Assert feature instrumentor based on the Mozilla JavaScript AST

espower

Power Assert feature instrumentor based on the Mozilla JavaScript AST.

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.

See CHANGELOG

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.

typedefault value
objectN/A

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

typedefault value
object(return value of espower.defaultOptions())

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

typedefault value
booleanfalse

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.

typedefault value
Array of stringobjects 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.

typedefault value
stringN/A

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

typedefault value
object or stringN/A

A raw (either as a string which can be JSON.parse'd, or an object) SourceMap associated with originalAst. This property is optional. If given, espower uses options.sourceMap to adjust information in the power-assert output.

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])'
    ]
}

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

$ npm install --save-dev espower

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>

Licensed under the MIT license.