Unit Testing

Unit testing means testing components of a program in isolation from each other to make sure every part works on its own before using it with others. Extensive testing helps avoid new updates causing unexpected side effects as well as alleviates general code rot (a more comprehensive wikipedia article on unit testing can be found here).

A typical unit test set calls some function or method with a given input, looks at the result and makes sure that this result looks as expected. Rather than having lots of stand-alone test programs, Evennia makes use of a central test runner. This is a program that gathers all available tests all over the Evennia source code (called test suites) and runs them all in one go. Errors and tracebacks are reported.

By default Evennia only tests itself. But you can also add your own tests to your game code and have Evennia run those for you.

Running the Evennia test suite

To run the full Evennia test suite, go to your game folder and issue the command

evennia test evennia

This will run all the evennia tests using the default settings. You could also run only a subset of all tests by specifying a subpackage of the library:

evennia test evennia.commands.default

A temporary database will be instantiated to manage the tests. If everything works out you will see how many tests were run and how long it took. If something went wrong you will get error messages. If you contribute to Evennia, this is a useful sanity check to see you haven’t introduced an unexpected bug.

Running custom game-dir unit tests

If you have implemented your own tests for your game you can run them from your game dir with

evennia test --settings settings.py .

The period (.) means to run all tests found in the current directory and all subdirectories. You could also specify, say, typeclasses or world if you wanted to just run tests in those subdirs.

An important thing to note is that those tests will all be run using the default Evennia settings. To run the tests with your own settings file you must use the --settings option:

evennia test --settings settings.py .

The --settings option of Evennia takes a file name in the mygame/server/conf folder. It is normally used to swap settings files for testing and development. In combination with test, it forces Evennia to use this settings file over the default one.

You can also test specific things by giving their path

evennia test --settings settings.py world.tests.YourTest

Writing new unit tests

Evennia’s test suite makes use of Django unit test system, which in turn relies on Python’s unittest module.

To make the test runner find the tests, they must be put in a module named test*.py (so test.py, tests.py etc). Such a test module will be found wherever it is in the package. It can be a good idea to look at some of Evennia’s tests.py modules to see how they look.

Inside the module you need to put a class inheriting (at any distance) from unittest.TestCase. Each method on that class that starts with test_ will be run separately as a unit test. There are two special, optional methods setUp and tearDown that will (if you define them) run before every test. This can be useful for setting up and deleting things.

To actually test things, you use special assert... methods on the class. Most common on is assertEqual, which makes sure a result is what you expect it to be.

Here’s an example of the principle. Let’s assume you put this in mygame/world/tests.py and want to test a function in mygame/world/myfunctions.py

    # in a module tests.py somewhere i your game dir
    import unittest

    from evennia import create_object
    # the function we want to test
    from .myfunctions import myfunc

    class TestObj(unittest.TestCase):
       "This tests a function myfunc."

       def setUp(self):
           """done before every of the test_ * methods below"""
           self.obj = create_object("mytestobject")
       def tearDown(self):
           """done after every test_* method below """
       def test_return_value(self):
           """test method. Makes sure return value is as expected."""
           actual_return = myfunc(self.obj)
           expected_return = "This is the good object 'mytestobject'."
           # test
           self.assertEqual(expected_return, actual_return)
       def test_alternative_call(self):
           """test method. Calls with a keyword argument."""
           actual_return = myfunc(self.obj, bad=True)
           expected_return = "This is the baaad object 'mytestobject'."
           # test
           self.assertEqual(expected_return, actual_return)

To test this, run

evennia test --settings settings.py .

to run the entire test module

evennia test --settings setings.py world.tests

or a specific class:

evennia test --settings settings.py world.tests.TestObj 

You can also run a specific test:

evennia test --settings settings.py world.tests.TestObj.test_alternative_call

You might also want to read the Python documentation for the unittest module.

Using the Evennia testing classes

Evennia offers many custom testing classes that helps with testing Evennia features. They are all found in evennia.utils.test_resources. Note that these classes implement the setUp and tearDown already, so if you want to add stuff in them yourself you should remember to use e.g. super().setUp() in your code.

Classes for testing your game dir

These all use whatever setting you pass to them and works well for testing code in your game dir.

  • EvenniaTest - this sets up a full object environment for your test. All the created entities can be accesses as properties on the class:

    • .account - A fake Account named “TestAccount”.

    • .account2 - Another account named “TestAccount2”

    • char1 - A Character linked to .account, named Char. This has ‘Developer’ permissions but is not a superuser.

    • .char2 - Another character linked to account, named Char2. This has base permissions (player).

    • .obj1 - A regular Object named “Obj”.

    • .obj2 - Another object named “Obj2”.

    • .room1 - A Room named “Room”. Both characters and both objects are located inside this room. It has a description of “room_desc”.

    • .room2 - Another room named “Room2”. It is empty and has no set description.

    • .exit - An exit named “out” that leads from .room1 to .room2.

    • .script - A Script named “Script”. It’s an inert script without a timing component.

    • .session - A fake Session that mimics a player connecting to the game. It is used by .account1 and has a sessid of 1.

  • EvenniaCommandTest - has the same environment like EvenniaTest but also adds a special .call() method specifically for testing Evennia Commands. It allows you to compare what the command actually returns to the player with what you expect. Read the call api doc for more info.

  • EvenniaTestCase - This is identical to the regular Python TestCase class, it’s just there for naming symmetry with BaseEvenniaTestCase below.

Here’s an example of using EvenniaTest

# in a test module

from evennia.utils.test_resources import EvenniaTest

class TestObject(EvenniaTest):
    """Remember that the testing class creates char1 and char2 inside room1 ..."""
    def test_object_search_character(self):
        """Check that char1 can search for char2 by name"""
        self.assertEqual(self.char1.search(self.char2.key), self.char2)
    def test_location_search(self):
        """Check so that char1 can find the current location by name"""
        self.assertEqual(self.char1.search(self.char1.location.key), self.char1.location)
        # ...

This example tests a custom command.

    from evennia.commands.default.tests import EvenniaCommandTest
from commands import command as mycommand

class TestSet(EvenniaCommandTest):
    "tests the look command by simple call, using Char2 as a target"

    def test_mycmd_char(self):
        self.call(mycommand.CmdMyLook(), "Char2", "Char2(#7)")

    def test_mycmd_room(self):
        "tests the look command by simple call, with target as room"
        self.call(mycommand.CmdMyLook(), "Room",
                  "Room(#1)\nroom_desc\nExits: out(#3)\n"
                  "You see: Obj(#4), Obj2(#5), Char2(#7)")

When using .call, you don’t need to specify the entire string; you can just give the beginning of it and if it matches, that’s enough. Use \n to denote line breaks and (this is a special for the .call helper), || to indicate multiple uses of .msg() in the Command. The .call helper has a lot of arguments for mimicing different ways of calling a Command, so make sure to read the API docs for .call().

Classes for testing Evennia core

These are used for testing Evennia itself. They provide the same resources as the classes above but enforce Evennias default settings found in evennia/settings_default.py, ignoring any settings changes in your game dir.

  • BaseEvenniaTest - all the default objects above but with enforced default settings

  • BaseEvenniaCommandTest - for testing Commands, but with enforced default settings

  • BaseEvenniaTestCase - no default objects, only enforced default settings

There are also two special ‘mixin’ classes. These are uses in the classes above, but may also be useful if you want to mix your own testing classes:

  • EvenniaTestMixin - A class mixin that creates all test environment objects.

  • EvenniaCommandMixin - A class mixin that adds the .call() Command-tester helper.

If you want to help out writing unittests for Evennia, take a look at Evennia’s coveralls.io page. There you see which modules have any form of test coverage and which does not. All help is appreciated!

Unit testing contribs with custom models

A special case is if you were to create a contribution to go to the evennia/contrib folder that uses its own database models. The problem with this is that Evennia (and Django) will only recognize models in settings.INSTALLED_APPS. If a user wants to use your contrib, they will be required to add your models to their settings file. But since contribs are optional you cannot add the model to Evennia’s central settings_default.py file - this would always create your optional models regardless of if the user wants them. But at the same time a contribution is a part of the Evennia distribution and its unit tests should be run with all other Evennia tests using evennia test evennia.

The way to do this is to only temporarily add your models to the INSTALLED_APPS directory when the test runs. here is an example of how to do it.

Note that this solution, derived from this stackexchange answer is currently untested! Please report your findings.

# a file contrib/mycontrib/tests.py

from django.conf import settings
import django
from evennia.utils.test_resources import BaseEvenniaTest

        "default": {
            "ENGINE": "django.db.backends.sqlite3"

class TestMyModel(BaseEvenniaTest):
    def setUp(self):
        if not settings.configured:

        from django.core.management import call_command
        from django.db.models import loading
        loading.cache.loaded = False
        call_command('syncdb', verbosity=0)

    def tearDown(self):

        from django.core.management import call_command
        from django.db.models import loading
        loading.cache.loaded = False
        call_command('syncdb', verbosity=0)

    # test cases below ...

    def test_case(self):
# test case here

A note on making the test runner faster

If you have custom models with a large number of migrations, creating the test database can take a very long time. If you don’t require migrations to run for your tests, you can disable them with the django-test-without-migrations package. To install it, simply:

$ pip install django-test-without-migrations

Then add it to your INSTALLED_APPS in your server.conf.settings.py:

    # ...

After doing so, you can then run tests without migrations by adding the --nomigrations argument:

evennia test --settings settings.py --nomigrations .