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A cross-platform UNIX way test non-framework for JavaScript.


If you have a general question, please ask it. I've created a issue to discuss Proof to notify you of updates. Use it to discuss what version 0.2.0 should be.

Please ask questions in the issue, on the Node.js listserv or come find me, in IRC on freenode as prettyrobots, I'm there most of the time.


Proof is a UNIX way test non-framework for the mightily lazy programmer.

In Proof, a unit test is a program. It does not need a runner to run. A program emits minimal Perl Test::Harness output. Failed assertions appear as comments in the file output.

You write your quick and dirty diagnostics to standard error. The test runner will hide it from you during normal test runs. If there is a test failure you can run the test program directly to see the error spew.

The Proof test runner execute test programs as child processes. If a test fails, even catastrophically, the test runner tests on.

Let the operating system do set up and tear down. When a test process exits, even when it fails catastrophically, resources are freed for the next test process. The test runner does not load or evaluate JavaScript, set tests up up or tear tests down. Why count on what amounts to a fragile program loader, when you've got a full blown operating system at your disposal?

When there is housekeeping to be done — databases to be reset, temporary files to be deleted — we still don't clean up after ourselves. We clean up before ourselves. You use Proof harnesses to clean up after the previous test process at the start of the next test process, when everything is stable.

With this in place, you are encouraged to be a slob in your test code. Each test is a short lived process, so feel free to suck up memory, leave file handles open, and leave sockets open. The operating system knows how to close them when your program exits. It won't affect the test runner, or test performance.

Well, you'll probably always be a meticulous programmer, who would never leave a file handle open, but still; you don't have to develop a strategy for error handling in code that is supposed to exercise edge cases. You don't have to try to catch the crazy monkey bananas thrown from code in development. You have a simple, universal strategy that works for normal operation, all tests passed, as well at the who-would-ever-have-imagined-that failures.

And that's not all.

Proof is convention over configuration until configuration is zero. Programs are organized into directories, which act as suites. The test runner will run suites in parallel, one test at a time from each suite. You don't have to think about parallel to get parallel. Your operating system does parallel for you just fine, so we use the operating system.

Proof is a parallel test runner, with a terse syntax that runs tests that are programs, and can handle almost any exception and keep running tests.


Via NPM.

npm install proof

To test via NPM, by extension Travis CI, create a package.json for your project that includes the following properties.

{   "name":             "fibonacci"
,   "version":          "1.0.3"
,   "author":           "Alan Gutierrez"
,   "directories":      { "lib" : "./lib" }
,   "devDependencies":  { "proof": "<=0.0.1" }
,   "scripts":          { "test": "proof test t/*/*.t" }
,   "main":             "./lib/fibonacci"

Now you can run npm test to test your project.

Every Test is a Program

Every test is a program.

Place your test in a file under a test directory in your project. Add a shebang line and make the file executable.

By convention, all tests are given a .t file extension, regardless of the language the test is written in. By convention, the test directory is named ./t relative to the project root, but ./test is good too.

Minimal unit test.

#!/usr/bin/env node
require('proof')(1, function (ok) {
  ok(true, 'true is true');

The first argument to test is the number of tests to expect. If to many or too few tests are run, the test runner will detect it and report it.

The call to require('proof') returns a function. You can call it immediately. That makes your test preamble quick and to the point.

This is analogous to the above.

#!/usr/bin/env node
var test = require('proof');

test(1, function (ok) {
  ok(true, 'true is true');

Here's a test with two assertions.

#!/usr/bin/env node
require('proof')(2, function (ok, equal) {
  ok(true, 'true is true');
  equal(2 + 2, 4, 'test addition');

You can see that the second argument to test is your program. All of the assertions in require("assert") are available to your test function, all you need to do is ask for them in your function arguments. Proof with give them to you as you need them.

Step by Step Asynchronous Tests

Proof has a built in control flow library ala Step, that simplifies testing of asynchronous code. Most of the time, you're going to simply want to step through a series of calls and bail out on the slightest error. Proof is ergonomically optimized for this common case.

#!/usr/bin/env node
var fs = require('fs');

require('proof')(1, function (step) {

  fs.readFile(__filename, step());

}, function (body, ok) {

  ok(/proof/.test(body), 'found proof');


For basic asynchronous testing, there's no need to nest your code into a temple of doom. The control flow library is there to keep your control flow shallow.

When you do need to some serious asynchronous spelukning, Proof also supports supports complicated asynchronous concepts like parallelism and branching.

#!/usr/bin/env node
var fs = require('fs');

// Antidisestablishmentarianism

require('proof')(1, function (step) {

  var tree = [ __dirname ], count;

  step(function nextDirectory () {

    if (tree.length) return tree.shift();
    else step(null, count);

  }, function (directory) {

    fs.readdir(directory, step());

  }, function nextEntry (list, directory, nextDirectory) {

    if (list.length) return path.resolve(directory, file);
    else step(nextDirectory)();

  }, function (file) {

    fs.stat(file, step());

  }, function (stat, file, nextEntry) {

    if (stat.isDirectory()) {
    } else {
      fs.readFile(file, 'utf8', step());

  }, function (body, nextEntry) {

    if (/Antidisestablishmentarianism/.test(body)) count++;


}, function (count) {

  ok(count, 1, 'one file contains possible seditious and blasphemous language');


The test above walks through the test directory asynchronously, looking for the word "Antidisestablishmentarianism" in the files it encounters. The above test proceeds through the directory tree serially, using named functions as branch labels to repeatedly visit each directory and file.

Shebang all the Languages

Actually, you an use any language with Proof. Emit TAP. Proof will report it.


echo "1..1"

true && echo "ok 1 truth is true"

You can use Proof to test your next C project, one that that has a dozens of little test programs that emit simple TAP.

You can use other languages to verify the integrity of your JavaScript library.

In Timezone, for example, I verify that my JavaScript time zone compiler correctly parses the IANA Timezone database using Ruby's strftime implementation. I wrote a Ruby program that emits TAP and tests each clock transition in the database.

Create More Tests More Frequently With Harnesses

With an Proof harness you can give a test everything it needs to run with as little as two lines of code.

Write a harness that does the setup for a test. It will load the libraries necessary to write a test against a subsystem of your project.

By convention, we name give our test harnesses a file name with a base of proof. This allows us to continue to require("./proof"), which is such a clever thing to say. The test harness file should have an extension of one of the supported languages, either .coffee, ._coffee, .js or ._js.

In the harness you create a context Object and stuff it with useful bits and pieces for your test.

module.exports = require('proof')(function () {
  context = {}
  context.example = { firstName: "Alan", lastName: "Gutierrez" }
  context.model = require("../../lib/model")
  return context;

You would place the above in a file named proof.js, for example.

Now you can write tests with a mere two lines of preamble. The common setup for the tests in your test suite is in your harness.

#!/usr/bin/env node
require('./proof')(2, function (example, model, equal) {
  equal(model.fullName(exmaple), "Alan Gutierrez", "full name");
  equal(model.lastNameFirst(exmaple), "Gutierrez, Alan", "last name first");

Asynchronous Harnesses

Some setup will require asynchronous calls. Database connections are a common case. You can create asynchronous harnesses by providing a callback function instead of an object to the require method in your harness.

The callback function will itself get a callback that is used to return an object that is given to the test program.

#!/usr/bin/env node

var mysql = require('mysql'), fs = require('fs');

module.exports = require('proof')(function (step) {

  fs.readFile('./configuration.json', 'utf8', step());

}, function (file) {

  var db = new mysql.Database(JSON.stringify(file));

}, function (connection) {

  return { connection: connection };


The test itself is no more complicated.

#!/usr/bin/env _coffee
require('./proof')(1, function (connection, step) {

  step(function () {

    connection.sql("SELECT COUNT(*) AS num FROM Employee", step());

  }, function (results) {

    equal(12, results[0].num, "employee count");



Note that, you can use asynchronous harnesses with synchronous tests, and create asynchronous tests from synchronous harnesses.


Proof defines the assertions ok, equal, notEqual, deepEqual, notDeepEqual, strictEqual, and notStrictEqual. They are identical to the assertions of the same named defined in the assert Node.js module, except that they print a message to stdout, instead of throwing an exception.

#!/usr/bin/env node
require('proof')(3, funciton (ok, equal, deepEqual) {
  ok(true, 'truth works');
  equal(1 + 1, 2, 'math works');
  deepEqual('a b'.split(/\s/), [ "a", "b" ], 'strings work');

Proof does not define a throws assertion. Instead, it uses the asynchronous control flow to test assertions.

When a step function in the control flow starts with the argument error, it indicates that this is an error handling step.

#!/usr/bin/env node
require('proof')(1, function () {

  throw new Error('oops');

}, function (error, equal) {

  equal(error.message, 'oops', 'error thrown');


If no error is thrown, the assertion is not test, the count of passed tests is wrong and the test fails.

You can test asynchronous error the same way.

#!/usr/bin/env node

var fs = require('fs');

require('proof')(1, function (step, say) {

  say('testing file not found'); // be chatty, why not?
  fs.readFile(__dirname + '/i-do-not-exist.txt', step());

}, function (error, equals) {

  equals(error.code, 'ENOENT', 'file does not exist');


Try not to worry about failure being inferred from count. It is actually really easy to see what what went wrong with a test with you keep your tests programs unit focused.

Exception Handling

When a test is healthy, it is healthy for the test to release resources. When a test fails catastrophically, Proof lets the operating system do the hard work of releasing system resources, such as memory, sockets and file handles.

Here's a test that opens a file handle, then closes it like a good citizen.

#!/usr/bin/env node

require('./proof')(1, function (step) {

  var buffer = new Buffer(2), fs = require('fs');

  step(function () {, "r", step());

  }, function (fd) {, buffer, 0, buffer.length, 0, step());

  }, function (equal) {

    equal(buffer.readInt16BE(0), 0x2321, 'shebang magic number');

    fs.close(fd, step())


But, what if there is a catastrophic error? Let's say that in the code above, the Buffer cannot be allocated because the system is out of memory. What happens? An exception is thrown, the process exits, and the operating system closes the file handle.

The operating system? Aren't we always supposed to close our own file handles?

Well, we could register an error handler to run at the last minute, or we could create a towering pyramid of try/catch blocks, but why bother? None of that will matter if your test has hung and you feed it a kill -9.

Trying to write exception handlers that account for every possible error that a test might find in code that is under active development is a tall order and a not a good use of your time.

Test code is supposed to raise unexpected exceptions. It is supposed to discover the unexpected. Let your tests find the exceptions. Let your operating system clean up after your tests when the exceptions are found.


Because each test is a short lived program, we can count on the operating system to reclaim resources like memory, file handles, and sockets when exceptions occur. But there is state that will not be reclaimed automatically. The most obvious example is temporary files and directories. We reclaim these using cleanup functions.

We're so meticulous, we run our cleanup functions twice for each test. Rather than counting on our test to clean up after itself, when it might be in bad shape due to some unforeseen error state, we count on it to always cleanup before itself, at the start of the test program, when it is most stable.

We do try to run our test again at exit. What we don't do is jump through hoops to ensure that our cleanup functions are called at exit. We could register exit handlers and create intricate try/catch blocks, but the test still might not run its cleanup functions at exit if the test exhausts system memory, segfaults, or gets a kill -9. We can't guarantee a cleanup at exit, so we don't count on it.

Because your cleanup functions are run twice, they must be idempotent, as the kids like to say. You must be able to run a cleanup function over and over again and get the same results. If a cleanup function deletes a temporary file, for example, it can't complain if the temporary file has already been deleted.

#!/usr/bin/env node

var mysql = require('mysql'), fs = require('fs');

module.exports = require('proof')(function (step) {
  var tmp = __dirname + '/tmp';

  step(function cleanup () { // named cleanup, so run again at exit

    // nested step delete of tmp directory and contents.
    step(function () {
      fs.readdir(tmp, step());
    }, function (error) {
      if (error.code == 'ENOENT') step(); // done
      else throw error; // unexpected
    }, function (list) {
      list.forEach(function (file) {
        fs.unlink(path.resolve(tmp, file), step());
    }, function () {
      fs.rmdir(tmp, step());

  }, function () {

    // create a new tmp directory for our test
    fs.mkdir(tmp, 0755, step());

  }, function () {

    // give our test the tmp directory
    return { tmp: tmp };


When we register a cleanup function, the cleanup function is called upon registration. Cleanup functions are run at the start of a test to cleanup in case our last test run exited abnormally. As long as the test does not exit abnormally, the cleanup function is called again at exit.

In the harness above, we register a cleanup function that deletes files in a temporary directory, then deletes the temporary directory. If the directory doesn't exist, that's okay, we catch the ENOENT exception and return. Because the cleanup function is called when we pass it to step, we're assured a clean slate. We call fs.mkdir without checking to see if it already exists. We know that it doesn't.

Now we can use our temporary directory in a test. The test doesn't have to perform any housekeeping. We can write test after test in the same suite, each one making use of this temporary directory, because it is cleaned up after or before every run.

#!/usr/bin/env node

var fs = require('fs'), exec = require('child_process').exec;

require('./proof')(1, function (tmp, step) {
  var program = tmp + '/'

  step(function () {
    fs.writeFile(program, '#!/bin/bash\nexit 1\n', 'utf8', step());
  }, function () {
    fs.chmod(program, 0755, step());
  }, function () {
    exec(program, step());
  }, function (error, equal) {
    equal(error.code, 1, 'exit code');

In the test above, we create a bash program to to test that error codes work correctly. If no exception is thrown, the test runner will report that a test was missed.

Tests can register cleanup functions too. It is generally easier to keep them in the harnesses, but its fine to use them in tests as well.

#!/usr/bin/env node

var fs = require('fs'), exec = require('child_process').exec;

require('./proof')(1, function (tmp, step) {
  var program = __dirname + '/'

  step(function cleanup() {
    step(function () {
      fs.unlink(program, step());
    }, function (error) {
      if (error.code != 'ENOENT') throw error;
  }, function () {
    fs.writeFile(program, '#!/bin/bash\nexit 1\n', 'utf8', step());
  }, function () {
    fs.chmod(program, 0755, step());
  }, function () {
    exec(program, step());
  }, function (error, equal) {
    equal(error.code, 1, 'exit code');

Here our test creates a temporary file in the same directory as the test, instead of in a harness provided temporary directory. It registers a cleanup function that deletes the file, so that the file is deleted before and after we write to it.

A useful pattern falls out of cleanup before. You may want to skip cleanup at exit so you can inspect the file output of a test. If so, you can set the environment variable UNTIDY=1 before running an individual test. It will cleanup before the test but not after. Now you can go through an edit, test, inspect cycle and watch how the output changes.

We count on cleanup before a test to allow us to keep running our tests until they pass, without having us have to stop and cleanup cruft after each because a test is exiting abnormally. If tests are exiting normally, regardless of whether they pass or fail, they will clean up after themselves, leaving your project directory nice and tidy after each run.

Running Tests

A test is a program. You can run a test to see its output.

$ t/logic/minimal.t
ok 1 true is true
ok 2 test arithmetic

By immutable convention, tests are grouped together by directory. The tests within a directory are considered a suite of tests. Test suites are generally kept in a directory t off the root of the project.

$ find t

You can run a test with the proof test runner to get gaudy console output with colors and non-ASCII characters (approximated below).

$ proof test t/logic/minimal.t
 ✓ t/logic/minimal.t ....................................... (2/2) 0.230 Success
                                      tests (1/1) assertions (2/2) 0.230 Success

Each test you pass to the test runner is will be run by the test runner. Tests in separate suites are run in parallel.

$ proof test t/logic/minimal.t t/regex/minimal.t
 ✓ t/logic/minimal.t ....................................... (2/2) 0.230 Success
 ✓ t/regex/minimal.t ....................................... (2/2) 0.331 Success
                                      tests (2/2) assertions (4/4) 0.561 Success

Tests Run in Parallel

As above.

$ proof test t/logic/minimal.t t/regex/minimal.t t/regex/complex.t
 ✓ t/logic/minimal.t ....................................... (2/2) 0.230 Success
 ✓ t/regex/minimal.t ....................................... (2/2) 0.331 Success
 ✓ t/regex/complex.t ....................................... (2/2) 1.045 Success
                                      tests (3/3) assertions (6/6) 1.606 Success

Because each test is a program, parallelism is simply a matter of running more than one test program at once. The default mode of the proof runner is to run four test programs a time.

The runner will run a test program from each suite, for up to four programs running at once. When a suite it complete, it moves onto the next one.

Tests within suites are run one after another, in the order in which they were specified on the command line.

If you design your tests so that they can run in any order, then you can run an entire suite of tests with globbing.

$ proof test t/*/*.t
 ✓ t/logic/minimal.t ....................................... (2/2)  .230 Success
 ✓ t/regex/minimal.t ....................................... (2/2)  .331 Success
 ✓ t/regex/complex.t ....................................... (2/2) 1.045 Success
                                      tests (3/3) assertions (6/6) 1.606 Success

Generally avoid making tests depend on being run in a specific order. That way you can get parallelism easily.

Suites run in parallel. You can group your tests however you like, by feature, subsystem, stages of workflow.

Make sure they can run in parallel though. You may have a single MySQL database to use for testing. You'll have to group all your MySQL tests in a suite, you can be sure that they won't stomp on each other. If your application supports either MySQL or PostgreSQL, you could run those tests in parallel.

If every test expects to hit a MySQL database, then create a separate MySQL database for each suite. Not a big deal, really, and then you have your tests running in parallel.

Continuous Integration With Travis CI

For an example of Travis CI output, you can look at the output from Proof itself.

With a minimal .travis.yml and Proof will work with Travis CI.

language: node_js

  - 0.6

  - npm install --dev
  - git submodule init && git submodule update

However, npm install --dev will recursively install development dependencies, bringing in all of CoffeeScript, which is not necessary. Explicitly installing your development dependencies makes your Travis CI output much less verbose.

language: node_js

  - 0.6

  - npm install
  - npm install proof coffee-script streamline
  - git submodule init && git submodule update

If you are not using Streamline.js exclude streamline. If you are not using CoffeeScript exclude coffee-script. Add additional development dependencies to suit your project's needs.

Change Log

Changes for each release.

Version 0.0.32.

Thu Jul 11 01:47:18 UTC 2013

Version 0.0.31

Mon Jul 8 14:52:16 UTC 2013

Version 0.0.30

Wed Jun 19 03:23:54 UTC 2013

Version 0.0.29

Fri Jun 14 00:17:21 UTC 2013

Version 0.0.28

Tue Apr 9 23:07:50 UTC 2013

Version 0.0.27

Thu Mar 21 08:54:41 UTC 2013

Version 0.0.26

Tue Mar 19 04:57:56 UTC 2013

Version 0.0.25

Mon Mar 18 07:20:00 UTC 2013

Version 0.0.24

Sun Mar 17 06:28:06 UTC 2013

Version 0.0.23

Sat Mar 16 06:03:02 UTC 2013

Version 0.0.22

Tue Mar 12 08:00:30 UTC 2013

Version 0.0.21

Tue Mar 12 06:52:06 UTC 2013

Version 0.0.20

Tue Mar 5 03:50:01 UTC 2013

Version 0.0.19

Tue Mar 5 03:22:27 UTC 2013

Version 0.0.18

Fri Mar 1 03:45:03 UTC 2013

Version 0.0.17

Mon Feb 18 07:42:56 UTC 2013

Version 0.0.16

Sun Dec 9 17:25:16 UTC 2012

Version 0.0.15

Fri Jul 13 17:00:01 UTC 2012

Version 0.0.14

Thu Jul 12 01:50:03 UTC 2012

Version 0.0.13

Wed Jul 11 22:43:24 UTC 2012

Version 0.0.12

Sun Jul 8 05:58:51 UTC 2012

Version 0.0.11

Sun Jul 8 05:24:13 UTC 2012

Version 0.0.10

Sat Jun 30 16:41:44 UTC 2012

Version 0.0.9

Fri Jun 29 13:59:21 UTC 2012

Version 0.0.8

Thu Jun 28 21:05:46 UTC 2012

Version 0.0.7

Wed Jun 27 18:22:41 UTC 2012

Version 0.0.6

Wed Jun 27 17:08:41 UTC 2012

Version 0.0.5

Sat Jun 16 10:01:21 UTC 2012

Version 0.0.4

Sun May 13 19:43:30 UTC 2012

Version 0.0.3

Sun May 13 17:24:09 UTC 2012

Version 0.0.2

Wed May 9 03:52:57 UTC 2012