Another testing framework for your meteor apps.
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Latest commit b6540b8 Jan 24, 2016 @apendua apendua Merge pull request #162 from dandv/patch-2
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What it's all about Circle CI

Gagarin is a mocha based testing framework designed to be used with Meteor. It can spawn multiple instances of your meteor application and run the tests by executing commands on both server and client in realtime. In other words, Gagarin allows you to automate everything you could achieve manually with meteor shell, browser console and a lot of free time. There's no magic. It just works.

Gagarin is also useful when you need more refined control over the meteor processes and test fancy things, e.g. the behavior of your app on server restarts or when you have multiple app instances writing to the same database. To our knowledge, this is currently not achievable with Velocity - the official Meteor testing framework.

Quick start

First, install the cli-tool with npm:

npm install -g gagarin

Put your tests in tests/gagarin/ directory, e.g.

// tests/gagarin/myFirstTestSuite.js

describe('My first Gagarin test suite', function () {
  var server = meteor();
  it('should just work', function () {
    return server.execute(function () { console.log('I am alive!'); });

Finally, in your project root directory run:

gagarin --verbose

We recommend running tests in verbose mode, at least before 1.0.0. Try gagarin --help if you need more options.

It is possible to use more advanced directory structures. You can, for example, place your test files in local package folders, without registering them in package.js. See Directory structure for more details.

Important notes

Gagarin is still under heavy development and a new release is published almost every week. Some parts of the API change over time and we can't guarantee backward compatibility before we reach 1.0.0. Minor version changes may contain breaking changes. Though, we put a lot of effort to reduce the risk of breaking old tests. Gagarin has it's own test suite with more than 250 test cases, which BTW are very good source of examples.

Windows support

Since version 0.4.10 gagarin can also run on windows platform. The only additional requirement is that it has to be run within the elevated prompt. This is because during the application build process we need to create a symbolic link to


which requires administrative rights. We are working hard to find a decent workaround (look here). Any help and suggestions are welcome.

Compatibility with various node versions

Gagarin should play nicely with node 0.10.x and 0.12.x. On the other hand, there are known compatibility issues with 0.11.x so we don't recommend using that particular version. It only applies to the cli-tool though. Your meteor application will always be run with the node from the development bundle corresponding to your current meteor release. Please keep this in mind if you are using any kind of continuous integration system, because it basically means that the appropriate version of meteor dev-tools will need to be downloaded before the tests can be run.

Breaking changes

Since version 0.4.0 the server object created by meteor() helper no longer has the location property. To make sure the browser starts on the proper location, you need to pass server as the first argument, so

var server = meteor();
var client = browser(server); // before 0.4.0 you would use server.location here

How is it different from Velocity?

Gagarin is external to meteor. It only takes care of spawning your meteor processes and allows you to execute chunks of source code in your app environment from within your test suite and that's it. On the other hand, Velocity will deeply integrate with your app by making your test cases an integral part of your app source code, but only in a special type of builds called mirrors. This is very clever because your tests will run as fast as they possibly can. The only drawback of using velocity is that you don't have a satisfactory control over your meteor processes. In most situations this is acceptable but there are some very specific scenarios when this is not sufficient. In those cases Gagarin is probably a good choice. Gagarin tests will run a little bit slower because the source code is sent to your app through DDP, but in most situations in which you would need Gagarin, this is totally acceptable because the bottleneck of your tests speed is usually somewhere else. Another advantage of using DDP is that the tests can be potentially executed on a deployed application which may be useful in some specific cases.

How is it different from Laika?

The truth is Gagarin originates from Laika. In some sense, one may think of it as Laika 2.0, though it's not backward compatible. The main advantages of using Gagarin rather then Laika are the following:

  • it does not depend on phantomjs
  • it does not depend on injected source code, so the test runner does not have to rebuild your app each time you run the tests
  • the communication with client is done through a real web driver API, which means that your tests can visit any web page and are not bound to your app's routes
  • it does not depend on external mongo processes; the tests runner is clever enough to find mongo executable within your meteor development bundle

Step-by-step guide

Gagarin is a simple test runner built on top of mocha. In it's essence is very similar to laika, though it's much more flexible, up-to-date and compatible with the latest Meteor versions. Currently it's implemented as a custom mocha interface, which simply extends the standard bdd ui. This may change in the future if there's a demand to support other testing frameworks.


Gagarin consists of two parts: gagarin npm module and anti:gagarin meteor package. The first one should be installed globally on your system, while the second one should be added to your meteor application. In order to work properly, the versions of the two guys must coincide.

The minimal setup

Please start by installing the cli tool:

npm install -g gagarin

If you try to run gagarin command in your meteor project directory you should receive an error message telling that there are no tests to run. Let's fix it by creating a dummy test in tests/gagarin/ directory.

// tests/gagarin/dummy.js
describe('A dummy test suite', function () {
  it('should do nothing', function () {});

This time, everything should work fine and your test should pass. Please note that prior to running the tests scenarios Gagarin builds your application as well. Should the build fail you will be notified accordingly. In case of problems, it's always good to try gagarin --verbose mode for better insight.

Gagarin will always look for your test scenarios in tests/gagarin/ directory. To alter this behavior pass a custom path as the first parameter, e.g.

gagarin path/to/my/tests

For more details see Directory structure and gagarin --help.

What about the anti:gagarin package?

If you forgot to add it manually, the gagarin cli-tool will make sure to add the right version to your project. If the dummy test passed you should notice that indeed the anti:gagarin package is listed in .meteor/packages file.

The role of the smart package is adding some backdoor functionality, similar to meteor shell, for testing purposes. But don't worry - it's only activate when GAGARIN_SETTINGS environment variable is present. For safety, double check it's not there in your production environment.

Directory structure

While we advise to place your tests in tests/gagarin to maintain compatibility with other (Velocity) testing frameworks, you're free to create a directory structure that fits your needs. Gagarin uses node-glob to find your test files based on a glob pattern.

By default, gagarin assumes you have placed your files inside tests/gagarin. By providing a glob as second argument, more advanced path structures are possible.

Example: tests under tests/gagarin



gagarin ./tests/gagarin

Example: tests directly under ./tests

  gagarin ./tests

Example: package only structure Let's say you maintain a 'package only' app, and would like to place your tests under the package they are testing. So your app lacks a global tests directory and looks somewhat similar to:


To run all tests found in local packages, you can provide a glob pattern like:

  gagarin ./packages/*/tests/*.js

Or if you have nested folders inside the tests folders:

  gagarin ./packages/*/tests/**/*.js

Example: multiple extensions Perhaps you have both .js files and .coffee files that you wish to run?

gagarin ./**/*.{js,coffee}

Example: global tests folder combined with package specific tests We can imagine you're having both global tests, and package specific tests in their own package directory. No problem, just run gagarin with a glob like:

gagarin ./**/tests/**/*.js

Run gagarin *pattern* --verbose if you need to find out witch tests files are being found by your pattern.

Some shells may expand wildcards. This will make gagarin load only the first test file matching the pattern. If you experience this problem, please wrap your pattern within "..." or '...'.

Writing simple tests

The simplest possible test suite may look like this:

describe('Example test suite', function () {
  var server = meteor();
  it('execute should work', function () {
    // return a promise
    return server.execute(function () {

In the above example meteor is a global function provided by the framework, which you can use to spawn new meteor instances.For your convenience we've also exposed expect from the good old chai.

Please note that the function passed to the server.execute routine is the only part that is executed within the server environment. The rest of the code is totally external to your application. This technique has a lot of advantages but it also have one major drawback. The functions which are passed to the server do not share their scope with the other ones. In particular, the following code

a = 0;
it('should print the value of a', function () {
  return server.execute(function () {

will throw an "undefined variable" error. Instead you should pass a as an argument

return server.execute(function (a) {
}, [ a ]);

Testing with browser

Gagarin makes it really easy to coordinate tests for client and server. For example

describe('You can also use browser in your tests', function () {
  var server = meteor();
  var client = browser(server);

  it('should work for both client and server', function () {
    return client.execute(function () {
      // some code to execute
    }).then(function () {
      return server.execute(function () {
        // some code to execute on server

This idea originated from Laika, but we decided to go for a more promise-oriented API. Basically speaking, you can use the browser function to spawn as many clients as you want. The only requirement is that you have a webdriver running somewhere. By default, gagarin will try to find webdriver at port 9515 (chromedriver default). You can customize the webdriver url by providing the corresponding option for the cli tool:

gagarin --webdriver http://localhost:9515

If you're testing locally, we recommend using chromedriver which can be downloaded from here. After unpacking the executable the only thing you need to do is to run it in the background. By default the process will listen on port 9515. This behavior can be altered by specifying the port explicitly

./chromedriver --port=1234

Other webdrivers can be used as well. If you plan to use phantomjs and GhostDriver please note that due to a BUG in GhostDriver all browser sessions will share the same cookie jar, which may be problematic in test scenarios when multiple concurrent users need to be created.

A part of webdriver API is exposed and ready to use within you client promise chain. For example:

it('should be able to use webdriver methods', function () {
  return client
    .then(function (title) {

The full list of supported methods is:


Additionally we've implemented a bunch of useful helpers, which you can use to simplify your tests.

Testing with Selenium WebDriver

We recommend using selenium 2.45.0 along with Firefox 36 or 34. Please note that webdriver is broken in Firefox 35, so don't even try to use that one. Also keep in mind that selenium is usually much slower than chromedriver so consider using larger timeouts values when you switch to Firefox.

Lets assume that you have a copy of selenium-server-standalone-*.jar available at /path/to/selenium.jar. First start a selenium "hub" with the following command:

java -jar /path/to/selenium.jar

Selenium server should be listening on port 4444 by default. Then run your Gagarin tests specifying --webdriver option

gagarin --webdriver http://localhost:4444/wd/hub

Please note the /wd/hub suffix! If you only try to connect at port 4444 the webdriver will not respond. We've been testing Gagarin with chrome (38) and firefox (34, 36). At this moment we cannot guarantee it will work with other browsers.


There are a few issues which we are aware of and we are working hard to minimize their impact on the user experience.

Mongo throwing 100 error

Sometimes, when you interrupt your tests with CTRL-C the test runner will fail to clean-up the mongo process running in the background. If you see this error, first try to find the process and kill it. If it does not help go to .gagarin/local/db and delete the mongo.lock file.

Tests fail due to timeouts

Depending on the environment and the system performance, the tests may require timeout values different from the default ones. Please keep this in mind and see gagarin --help for available customization options. In case of problems, it's generally good to run tests in --verbose mode to have a better picture of what's going on.

before all timeout

If you run your tests in --verbose mode you would notice that this is happening because sometimes webdriver fails to respond within a reasonable time window when we create a new browser session. This may also depend on your system resources. It's totally external to Gagarin, so the only thing we can do is to report this error properly.


Since we don't have a comprehensive documentation yet, please consider the following set of simple examples as a current API reference.

Scope of the a local variable

It's good to keep in mind that the code which is intended to be executed on either server or client is passed as a string. Of course it does not have an immediate access to your local variable scope. In particular, things like:

var a = 1;
it("should be able to access local variable", function () {
  return client.execute(function () {
    return a + 1;

will throw "a is undefined". Trying to set a = 1; will throw as well because the code is implicitly executed in strict mode, which does not allow introducing new variables to the global scope.

Passing arguments to client and server code

If you don't need to modify the variables within your "remote" code then probably the easiest way to overcome the problem described above is to pass local scope variables as arguments:

var a = 1;
it("should be able to access local variable", function () {
  return client.execute(function (a) {
    return a + 1;
  }, [ a ]); // array of arguments

Note that this construction will already allow you to do anything you want with your local variables, because you can always update them within then, after your client/server computation is done. However, it's not very convenient in more complicated scenarios.

Copying closure

To simplify the interaction between client and server code, we've added an affordance to reuse the declared closure in all three environments: test scope, server and client. To this end, you need to explicitly provide a list of variables to be synced as well as an accessor function:

var a = 1, b = 2, c = 0;
// this is a hack :)
closure(['a', 'b', 'c'], function (key, value) {
  return eval(key + (arguments.length > 1 ? '=' + JSON.stringify(value) : ''));

Now this code should work without problems:

it("should be able to access local variables", function () {
  return client.execute(function (a) {
    c = a + b;
  }).then(function () {

The only reserved variable name for closures is $, which you probably would not like to use for other reasons.

Asynchronous test cases

On both server and client you can also use asynchronous scripts:

it("should be able to do work asynchronously", function () {
  return server.promise(function (resolve) {
    setTimeout(function () {
    }, 1000);
  }).then(function (value) {

The second argument to the promise is reject, so if you want to throw asynchronously:

it("should be able throw asynchronously", function () {
  return server.promise(function (resolve, reject) {
    setTimeout(function () {
     reject(new Error("this is some fake error"));
    }, 1000);
  }).expectError(function (err) {
    expect(err.message).to.contain("fake error");

If you want to pass additional variables to promise method, do it like this:

it("should be able to pass arguments", function () {
  return server.promise(function (resolve, reject, arg1, arg2) {
    setTimeout(function () {
     resolve(arg1 + arg2);
    }, 1000);
  }, [ 1, 2 ]).then(function (value) {

Waiting for conditions

There's also a useful helper to wait for conditions. Again, it works on both server and client:

before(function () {
  return client.execute(function () {
    Items.insert({_id: 'someFakeId'});

it("should be able to wait on server", function () {
  return server.wait(1000, 'until data is propagated to the server', function () {
    return Items.findOne({_id: 'someFakeId'});
  }).then(function (value) {

For contributors

To test the package locally make sure that a webdriver is listening on port 9515, then simply run the tests with the following command

npm test

or just

./test.js [options]

in the project root directory. Additionally you can use

./test.js --help

to display information about all possible options. For example, to use a different webdriver location, you can specify it with

./test.js --webdriver http://localhost:4444/wd/hub

For testing purposes it's sometimes useful to install a version of the npm package from a specific branch.

npm install -g anticoders/gagarin#develop

If you're developing Gagarin locally please remember that anti:gagarin package is an integral part of the testing framework and it has to be consistent with the gagarin node module. The easiest way to achieve this is to put a symbolic link inside the packages directory within your project root, i.e.

path/to/your/project/packages/anti:gagarin -> path/to/repos/gagarin


MIT licensed

Copyright (C) 2015 Tomasz Lenarcik,