nodeunit

Nodeunit

A simple unit testing tool based on the node.js assert module.

• Simple to use
• Just export the tests from a module
• Helps you avoid common pitfalls when testing asynchronous code
• Easy to add test cases with setUp and tearDown functions if you wish
• Allows the use of mocks and stubs

Contributors

• sstephenson - coffee-script support
• and thanks to cjohansen for input and advice on implementing setUp and tearDown functions. See cjohansen's fork.

Also, check out gerad's nodeunit-dsl project, which implements a 'pretty dsl on top of nodeunit'.

Usage

Here is an example unit test module:

exports.testSomething = function(test){
    test.expect(1);
    test.ok(true, "this assertion should pass");
    test.done();
};

exports.testSomethingElse = function(test){
    test.ok(false, "this assertion should fail");
    test.done();
};

When run using the included testrunner, this will output the following:

Installation

There are two options for installing nodeunit:

1. Clone / download nodeunit from github, then:

   make && sudo make install

2. Install via npm:

   npm install nodeunit

API Documentation

Nodeunit uses the functions available in the node.js assert module:

• ok(value, [message]) - Tests if value is a true value.
• equal(actual, expected, [message]) - Tests shallow, coercive equality with the equal comparison operator ( == ).
• notEqual(actual, expected, [message]) - Tests shallow, coercive non-equality with the not equal comparison operator ( != ).
• deepEqual(actual, expected, [message]) - Tests for deep equality.
• notDeepEqual(actual, expected, [message]) - Tests for any deep inequality.
• strictEqual(actual, expected, [message]) - Tests strict equality, as determined by the strict equality operator ( === )
• notStrictEqual(actual, expected, [message]) - Tests strict non-equality, as determined by the strict not equal operator ( !== )
• throws(block, [error], [message]) - Expects block to throw an error.
• doesNotThrow(block, [error], [message]) - Expects block not to throw an error.
• ifError(value) - Tests if value is not a false value, throws if it is a true value. Useful when testing the first argument, error in callbacks.

Nodeunit also provides the following functions within tests:

• expect(amount) - Specify how many assertions are expected to run within a test. Very useful for ensuring that all your callbacks and assertions are run.
• done() - Finish the current test function, and move on to the next. ALL tests should call this!

Nodeunit aims to be simple and easy to learn. This is achieved through using existing structures (such as node.js modules) to maximum effect, and reducing the API where possible, to make it easier to digest.

Tests are simply exported from a module, but they are still run in the order they are defined.

Note: Users of old nodeunit versions may remember using ok, equals and same in the style of qunit, instead of the assert functions above. These functions still exist for backwards compatibility, and are simply aliases to their assert module counterparts.

Asynchronous Testing

When testing asynchronous code, there are a number of sharp edges to watch out for. Thankfully, nodeunit is designed to help you avoid as many of these pitfalls as possible. For the most part, testing asynchronous code in nodeunit just works.

Tests run in series

While running tests in parallel seems like a good idea for speeding up your test suite, in practice I've found it means writing much more complicated tests. Because of node's module cache, running tests in parallel means mocking and stubbing is pretty much impossible. One of the nicest things about testing in javascript is the ease of doing stubs:

var _readFile = fs.readFile;
fs.readFile = function(path, callback){
    // its a stub!
};
// test function that uses fs.readFile

// we're done
fs.readFile = _readFile;

You cannot do this when running tests in parallel. In order to keep testing as simple as possible, nodeunit avoids it. Thankfully, most unit-test suites run fast anyway.

Explicit ending of tests

When testing async code its important that tests end at the correct point, not just after a given number of assertions. Otherwise your tests can run short, ending before all assertions have completed. Its important to detect too many assertions as well as too few. Combining explicit ending of tests with an expected number of assertions helps to avoid false test passes, so be sure to use the test.expect() method at the start of your test functions, and test.done() when finished.

Groups, setUp and tearDown

Nodeunit allows the nesting of test functions:

exports.test1 = function (test) {
    ...
}

exports.group = {
    test2: function (test) {
        ...
    },
    test3: function (test) {
        ...
    }
}

This would be run as:

test1
group - test2
group - test3

Using these groups its possible to add setUp and tearDown functions to your tests. Nodeunit has a utility function called testCase which allows you to define a setUp function, which is run before each test, and a tearDown function, which is run after each test calls test.done():

var testCase = require('nodeunit').testCase;

module.exports = testCase({
    setUp: function () {
        this.foo = 'bar';
    },
    tearDown: function () {
        // clean up
    },
    test1: function (test) {
        test.equals(this.foo, 'bar');
        test.done();
    }
});

In this way, its possible to have multiple groups of tests in a module, each group with its own setUp and tearDown functions.

Running Tests

Nodeunit comes with a basic command-line test runner, which can be installed using 'sudo make install'. Example usage:

nodeunit testmodule1.js testfolder [...]

The testrunner uses color output, because I think that's more fun :) I intend to add a no-color option in future. To give you a feeling of the fun you'll be having writing tests, lets fix the example at the start of the README:

Ahhh, Doesn't that feel better?

You can also add some code to the bottom of your test modules so they can be run directly from the command-line:

if(module.id == '.'){
    var testrunner = require('nodeunit').testrunner;
    testrunner.run([__filename]);
}

NOTE: this requires nodeunit to be in your require paths. You can make nodeunit available to all your projects by copying it to ~/.node-libraries or installing it via npm.

When using the included test runner, it will exit using the failed number of assertions as the exit code. Exiting with 0 when all tests pass.

Adding nodeunit to Your Projects

If you don't want people to have to install the nodeunit command-line tool, you'll want to create a script that runs the tests for your project with the correct require paths set up. Here's an example test script, with deps, lib and test directories:

#!/usr/bin/env node

require.paths.push(__dirname);
require.paths.push(__dirname + '/deps');
require.paths.push(__dirname + '/lib');
var testrunner = require('nodeunit').testrunner;

process.chdir(__dirname);
testrunner.run(['test']);

If you're using git, you might find it useful to include nodeunit as a submodule. Using submodules makes it easy for developers to download nodeunit and run your test suite, without cluttering up your repository with the source code. To add nodeunit as a git submodule do the following:

git submodule add git://github.com/caolan/nodeunit.git deps/nodeunit

This will add nodeunit to the deps folder of your project. Now, when cloning the repository, nodeunit can be downloaded by doing the following:

git submodule init
git submodule update

Let's update the test script above with a helpful hint on how to get nodeunit, if its missing:

#!/usr/bin/env node

require.paths.push(__dirname);
require.paths.push(__dirname + '/deps');
require.paths.push(__dirname + '/lib');

try {
    var testrunner = require('nodeunit').testrunner;
}
catch(e) {
    var sys = require('sys');
    sys.puts("Cannot find nodeunit module.");
    sys.puts("You can download submodules for this project by doing:");
    sys.puts("");
    sys.puts("    git submodule init");
    sys.puts("    git submodule update");
    sys.puts("");
    process.exit();
}

process.chdir(__dirname);
testrunner.run(['test']);

Now if someone attempts to run your test suite without nodeunit installed they will be prompted to download the submodules for your project.

Writing a Test Runner

Nodeunit exports runTest(fn, options), runModule(mod, options) and runFiles(paths, options). You'll most likely want to run test suites from files, which can be done using the latter function. The options argument can contain callbacks which run during testing. Nodeunit provides the following callbacks:

• moduleStart(name) - called before a module is tested
• moduleDone(name, assertions) - called once all test functions within the module have completed (see assertions object reference below) ALL tests within the module
• testStart(name) - called before a test function is run
• testDone(name, assertions) - called once a test function has completed (by calling test.done())
• log(assertion) - called whenever an assertion is made (see assertion object reference below)
• done(assertions) - called after all tests/modules are complete

The assertion object:

• passed() - did the assertion pass?
• failed() - did the assertion fail?
• error - the AssertionError if the assertion failed
• method - the nodeunit assertion method used (ok, same, equals...)
• message - the message the assertion method was called with (optional)

The assertionList object:

• An array-like object with the following new attributes:
  • failures - the number of assertions which failed
  • duration - the time taken for the test to complete in msecs

For a reference implementation of a test runner, see lib/testrunner.js in the nodeunit project directory.

Running the nodeunit Tests

The tests for nodeunit are written using nodeunit itself as the test framework. However, the module test-base.js first does some basic tests using the assert module to ensure that test functions are actually run, and a basic level of nodeunit functionality is available.

To run the nodeunit tests do:

make test

Note: There was a bug in node v0.2.0 causing the tests to hang, upgrading to v0.2.1 fixes this.