This library is a super small wrapper over node’s assert module that has two
things: (1) the ability to disable assertions with the environment variable
NODE_NDEBUG, and (2) some API wrappers for argument testing. Like
assert.string(myArg, 'myArg')
. As a simple example, most of my code looks
like this:
var assert = require('assert-plus');
function fooAccount(options, callback) {
assert.object(options, 'options');
assert.number(options.id, 'options.id');
assert.bool(options.isManager, 'options.isManager');
assert.string(options.name, 'options.name');
assert.arrayOfString(options.email, 'options.email');
assert.func(callback, 'callback');
// Do stuff
callback(null, {});
}
All methods that aren’t part of node’s core assert API are simply assumed to
take an argument, and then a string ‘name’ that’s not a message; AssertionError
will be thrown if the assertion fails with a message like:
AssertionError: foo (string) is required
at test (/home/mark/work/foo/foo.js:3:9)
at Object.<anonymous> (/home/mark/work/foo/foo.js:15:1)
at Module._compile (module.js:446:26)
at Object..js (module.js:464:10)
at Module.load (module.js:353:31)
at Function._load (module.js:311:12)
at Array.0 (module.js:484:10)
at EventEmitter._tickCallback (node.js:190:38)
from:
function test(foo) {
assert.string(foo, 'foo');
}
There you go. You can check that arrays are of a homogeneous type with Arrayof$Type
:
function test(foo) {
assert.arrayOfString(foo, 'foo');
}
You can assert IFF an argument is not undefined
(i.e., an optional arg):
assert.optionalString(foo, 'foo');
Lastly, you can opt-out of assertion checking altogether by setting the
environment variable NODE_NDEBUG=1
. This is pseudo-useful if you have
lots of assertions, and don’t want to pay typeof ()
taxes to v8 in
production. Be advised: The standard functions re-exported from assert
are
also disabled in assert-plus if NDEBUG is specified. Using them directly from
the assert
module avoids this behavior.
The complete list of APIs is:
npm install assert-plus
The MIT License (MIT) Copyright © 2012 Mark Cavage
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