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Generate fixture modules from folders


Generate a fixture from a folder on disk:

tacks /path/to/fixture/example > example.js

Create and destroy the fixture from your tests:

var Tacks = require('tacks')
var Dir = Tacks.Dir
var File = Tacks.File
var Symlink = Tacks.Symlink
// I like my fixture paths to match my test filename:
var fixturepath = path.join(__dirname, path.basename(__filename, '.js'))
var example = require('./example.js')

Or create your own fixture inline:

var example = new Tacks(Dir({
  'package.json': File({
    name: 'example',
    version: '1.0.0'


This is very much a "release early" type release. Still very much in progress, but being used.


These are used in the generated code. It's totally legit to write them directly though.


var fixture = new Tacks(Dir({
  'package.json': File({
    name: 'example',
    version: '1.0.0'

Create a new fixture object based on a Dir object, see below.

Create Fixture On Disk


Take the directory and files described by the fixture and create it in /path/to/fixture

Remove Fixture From Disk


Cleanup a fixture we installed in /path/to/fixture.

Add Directory

var Dir = Tacks.Dir
var mydir = Tacks.Dir(dirspec)

Creates a new Dir object for consumption by new Tacks. dirspec is a object whose properties are the names of files in a directory and whose values are either File objects, Dir objects or Symlink objects.

Add File

var File = Tacks.File
var myfile = Tacks.File(filespec)

Creates a new File object for use in Dir objects. filespec can be either a String, a Buffer or an Object. In the last case, it will be stringified with JSON.stringify before writing it to disk

Add Symlink

var Symlink = Tacks.Symlink
var mysymlink = Tacks.Symlink(destination)

Creates a new Symlink object for use in Dir objects. destination should either be relative to where the symlink is being created, or absolute relative to the root of the fixture. That is, Tacks.Symlink('/') will create a symlink pointing at the fixture root.

Generate Fixture Object From Directory

var loadFromDir = require('tacks/load-from-dir')
var onDisk = loadFromDir('tests/example')

The value returned is a Tacks object that you can call create or remove on. It's also handy for using in tests use compare an in memory tacks fixture to whatever ended up on disk.

Assert Two Fixtures The Same With node-tap

var test = require('tap').test
var tacksAreTheSame = require('tacks/tap').areTheSame
test('example', function (t) {
  return tacksAreTheSame(t, actual, expected, 'got the expected results')

The tacks/tap submodule is the start of tap assertions for comparing fixtures.

areTheSame creates a subtest, and inside that subtest runs a bunch of assertions comparing the contents of the two models. It's smart enough to consider tacks equivalent things equal, eg strings & buffers with the same content.

Because it creates a subtest, it's async, it returns the subtest (which is also a promise) so you can either return it yourself and your test will complete when it does, or do something like:

  tacksAreTheSame(t, actual, expected, 'got the expected results').then(t.done)


  tacksAreTheSame(t, actual, expected, 'got the expected results').then(function () {
    … more tests …

Geneate JavaScript From Directory

var generateFromDir = require('tacks/generate-from-dir')
var fixturestr = Tacks.generateFromDir(dir)

This is what's used by the commandline– it generates javascript as a string from a directory on disk. It works hard to produce something that looks like it might have been typed by a human– It translates JSON on disk into object literals. And it doesn't quote property names in object literals unless it has to. It uses single quotes when it can. It double quotes when it has to, and escapes when it has no other choice. It includs plain text as strings concatenated one per line. For everything else it makes Buffer objects using hex encoded strings as input.


These are things I'll do sooner or late myself.

  • Include adding a .mockFs('/tmp/fixture/path/') function which returns a patched version of fs that, for attempts to read from /tmp/fixture/path returns data from the in memory fixture instead of looking at the filesystem. For injection into tested modules with something like require-inject.


I'd love to see these, but I may never get time to do them myself. If someone else did them though…

  • Having some way to control the formatting of the generated output would be nice for folks who don't use standard… eg, semicolons, indentation, default quoting. The right answer might be to generate AST objects for use by an existing formatter. Relatedly, it'd be nice to have some standard extension method for the generated sourcecode. Right now I make use of it just by concattenating source code.