zulip/docs/testing.md

Testing and writing tests

Running tests

To run the full Zulip test suite, do this:

./tools/test-all

Zulip tests must be run inside a Zulip development environment; if you're using Vagrant, you will need to enter the Vagrant environment before running the tests:

vagrant ssh
cd /srv/zulip

This runs the linter (tools/lint-all) plus all of our test suites; they can all be run separately (just read tools/test-all to see them). You can also run individual tests which can save you a lot of time debugging a test failure, e.g.:

./tools/lint-all # Runs all the linters in parallel
./tools/test-backend zerver.tests.test_bugdown.BugdownTest.test_inline_youtube
./tools/test-js-with-casper 09-navigation.js
./tools/test-js-with-node # Runs all node tests but is very fast

Schema and initial data changes

If you change the database schema or change the initial test data, you have to regenerate the pristine test database by running tools/do-destroy-rebuild-test-database.

Wiping the test databases

You should first try running: tools/do-destroy-rebuild-test-database

If that fails you should try to do:

sudo -u postgres psql
> DROP DATABASE zulip_test;
> DROP DATABASE zulip_test_template;

and then run tools/do-destroy-rebuild-test-database

Recreating the postgres cluster

warning

This is irreversible, so do it with care, and never do this anywhere in production.

If your postgres cluster (collection of databases) gets totally trashed permissions-wise, and you can't otherwise repair it, you can recreate it. On Ubuntu:

sudo pg_dropcluster --stop 9.1 main
sudo pg_createcluster --locale=en_US.utf8 --start 9.1 main

Backend Django tests

These live in zerver/tests/tests.py and zerver/tests/test_*.py. Run them with tools/test-backend.

Web frontend black-box casperjs tests

These live in frontend_tests/casper_tests/. This is a "black box" test; we load the frontend in a real (headless) browser, from a real dev server, and simulate UI interactions like sending messages, narrowing, etc.

Since this is interacting with a real dev server, it can catch backend bugs as well.

You can run this with ./tools/test-js-with-casper or as ./tools/test-js-with-casper 06-settings.js to run a single test file from frontend_tests/casper_tests/.

Debugging Casper.JS

Casper.js (via PhantomJS) has support for remote debugging. However, it is not perfect. Here are some steps for using it and gotchas you might want to know.

To turn on remote debugging, pass --remote-debug to the ./frontend_tests/run-casper script. This will run the tests with port 7777 open for remote debugging. You can now connect to localhost:7777 in a Webkit browser. Somewhat recent versions of Chrome or Safari might be required.

• When connecting to the remote debugger, you will see a list of pages, probably 2. One page called about:blank is the headless page in which the CasperJS test itself is actually running in. This is where your test code is.
• The other page, probably localhost:9981, is the Zulip page that the test is testing---that is, the page running our app that our test is exercising.

Since the tests are now running, you can open the about:blank page, switch to the Scripts tab, and open the running 0x-foo.js test. If you set a breakpoint and it is hit, the inspector will pause and you can do your normal JS debugging. You can also put breakpoints in the Zulip webpage itself if you wish to inspect the state of the Zulip frontend.

You can also check the screenshots of failed tests at /tmp/casper-failure*.png.

If you need to use print debugging in casper, you can do using casper.log; see http://docs.casperjs.org/en/latest/logging.html for details.

An additional debugging technique is to enable verbose mode in the Casper tests; you can do this by adding to the top of the relevant test file the following:

var casper = require('casper').create({
   verbose: true,
   logLevel: "debug"
});

This can sometimes give insight into exactly what's happening.

Web frontend unit tests

As an alternative to the black-box whole-app testing, you can unit test individual JavaScript files that use the module pattern. For example, to test the foobar.js file, you would first add the following to the bottom of foobar.js:

if (typeof module !== 'undefined') {
    module.exports = foobar;
}

This makes foobar.js follow the CommonJS module pattern, so it can be required in Node.js, which runs our tests.

Now create frontend_tests/node_tests/foobar.js. At the top, require the Node.js assert module, and the module you're testing, like so:

var assert = require('assert');
var foobar = require('js/foobar.js');

(If the module you're testing depends on other modules, or modifies global state, you need to also read the next section.)

Define and call some tests using the assert module. Note that for "equal" asserts, the actual value comes first, the expected value second.

(function test_somefeature() {
    assert.strictEqual(foobar.somefeature('baz'), 'quux');
    assert.throws(foobar.somefeature('Invalid Input'));
}());

The test runner (index.js) automatically runs all .js files in the frontend_tests/node directory.

Coverage reports

You can automatically generate coverage reports for the JavaScript unit tests. To do so, install istanbul:

sudo npm install -g istanbul

And run test-js-with-node with the 'cover' parameter:

tools/test-js-with-node cover

Then open coverage/lcov-report/js/index.html in your browser. Modules we don't test at all aren't listed in the report, so this tends to overstate how good our overall coverage is, but it's accurate for individual files. You can also click a filename to see the specific statements and branches not tested. 100% branch coverage isn't necessarily possible, but getting to at least 80% branch coverage is a good goal.

Writing tests

Writing Casper tests

Probably the easiest way to learn how to write Casper tests is to study some of the existing test files. There are a few tips that can be useful for writing Casper tests in addition to the debugging notes below:

• Run just the file containing your new tests as described above to have a fast debugging cycle.

• With frontend tests in general, it's very important to write your code to wait for the right events. Before essentially every action you take on the page, you'll want to use waitForSelector, waitUntilVisible, or a similar function to make sure the page or elemant is ready before you interact with it. For instance, if you want to click a button that you can select via #btn-submit, and then check that it causes success-elt to appear, you'll want to write something like:

  casper.waitForSelector("#btn-submit", function () {
     casper.click('#btn-submit')
     casper.test.assertExists("#success-elt");
   });
  

  This will ensure that the element is present before the interaction is attempted. The various wait functions supported in Casper are documented in the Casper here: http://docs.casperjs.org/en/latest/modules/casper.html#waitforselector and the various assert statements available are documented here: http://docs.casperjs.org/en/latest/modules/tester.html#the-tester-prototype

• Casper uses CSS3 selectors; you can often save time by testing and debugging your selectors on the relevant page of the Zulip development app in the Chrome javascript console by using e.g. $$("#settings-dropdown").

• The test suite uses a smaller set of default user accounts and other data initialized in the database than the development environment; to see what differs check out the section related to options["test_suite"] in zilencer/management/commands/populate_db.py.

• Casper effectively runs your test file in two phases -- first it runs the code in the test file, which for most test files will just collect a series of steps (each being a casper.then or casper.wait... call). Then, usually at the end of the test file, you'll have a casper.run call which actually runs that series of steps. This means that if you write code in your test file outside a casper.then or casper.wait... method, it will actually run before all the Casper test steps that are declared in the file, which can lead to confusing failures where the new code you write in between two casper.then blocks actually runs before either of them. See this for more details about how Casper works: http://docs.casperjs.org/en/latest/faq.html#how-does-then-and-the-step-stack-work

Handling dependencies in unit tests

The following scheme helps avoid tests leaking globals between each other.

First, if you can avoid globals, do it, and the code that is directly under test can simply be handled like this:

var search = require('js/search_suggestion.js');

For deeper dependencies, you want to categorize each module as follows:

• Exercise the module's real code for deeper, more realistic testing?
• Stub out the module's interface for more control, speed, and isolation?
• Do some combination of the above?

For all the modules where you want to run actual code, add a statement like the following to the top of your test file:

add_dependencies({
    _: 'third/underscore/underscore.js',
    util: 'js/util.js',
    Dict: 'js/dict.js',
    Handlebars: 'handlebars',
    Filter: 'js/filter.js',
    typeahead_helper: 'js/typeahead_helper.js',
    stream_data: 'js/stream_data.js',
    narrow: 'js/narrow.js'
});

For modules that you want to completely stub out, please use a pattern like this:

set_global('page_params', {
    email: 'bob@zulip.com'
});

// then maybe further down
global.page_params.email = 'alice@zulip.com';

Finally, there's the hybrid situation, where you want to borrow some of a module's real functionality but stub out other pieces. Obviously, this is a pretty strong smell that the other module might be lacking in cohesion, but that code might be outside your jurisdiction. The pattern here is this:

// Use real versions of parse/unparse
var narrow = require('js/narrow.js');
set_global('narrow', {
    parse: narrow.parse,
    unparse: narrow.unparse
});

// But later, I want to stub the stream without having to call super-expensive
// real code like narrow.activate().
global.narrow.stream = function () {
    return 'office';
};

Manual testing (local app + web browser)

Clearing the manual testing database

You can use:

./tools/do-destroy-rebuild-database

to drop the database on your development environment and repopulate your it with the Shakespeare characters and some test messages between them. This is run automatically as part of the development environment setup process, but is occasionally useful when you want to return to a clean state for testing.

JavaScript manual testing

debug.js has some tools for profiling Javascript code, including:

• `print_elapsed_time`: Wrap a function with it to print the time that function takes to the javascript console.
• `IterationProfiler`: Profile part of looping constructs (like a for loop or $.each). You mark sections of the iteration body and the IterationProfiler will sum the costs of those sections over all iterations.

Chrome has a very good debugger and inspector in its developer tools. Firebug for Firefox is also pretty good. They both have profilers, but Chrome's is a sampling profiler while Firebug's is an instrumenting profiler. Using them both can be helpful because they provide different information.

Python 3 Compatibility

Zulip is working on supporting Python 3, and all new code in Zulip should be Python 2+3 compatible. We have converted most of the codebase to be compatible with Python 3 using a suite of 2to3 conversion tools and some manual work. In order to avoid regressions in that compatibility as we continue to develop new features in zulip, we have a special tool, tools/check-py3, which checks all code for Python 3 syntactic compatibility by running a subset of the automated migration tools and checking if they trigger any changes. tools/check-py3 is run automatically in Zulip's Travis CI tests to avoid any regressions, but is not included in test-all since it is quite slow.

To run tooks/check-py3, you need to install the modernize and future python packages (which are included in requirements/py3k.txt, which itself is included in requirements/dev.txt, so you probably already have these packages installed).

To run check-py3 on just the python files in a particular directory, you can change the current working directory (e.g. cd zerver/) and run check-py3 from there.