{"id":993,"date":"2022-02-20T20:48:13","date_gmt":"2022-02-20T20:48:13","guid":{"rendered":"https:\/\/zerotobyte.com\/?p=993"},"modified":"2022-02-20T20:48:14","modified_gmt":"2022-02-20T20:48:14","slug":"django-unit-test-explained-with-examples-part-1","status":"publish","type":"post","link":"https:\/\/zerotobyte.com\/django-unit-test-explained-with-examples-part-1\/","title":{"rendered":"Django Unit Test – Explained with Examples – Part 1"},"content":{"rendered":"\n

As the web application grows and more complex features are implemented, testing becomes inevitable. Testing can usually be done in many ways – the more the better<\/strong>. This includes manual tests performed by a human tester, unit tests, performance tests, integrations tests, etc.\u00a0 In this article, we will focus merely on how to write and run a Django unit test<\/strong>. <\/p>\n\n\n\n

If you wish to go straight to practical examples, skip to another post where I laid out an extensive set of Django unit test examples.<\/p>\n\n\n\n

What are unit tests?<\/h2>\n\n\n\n

In programming, unit tests<\/a> are a type of automated tests implemented by a programmer. Each unit test has the purpose of validating a behavior happening in a specific section (also called unit) or component of an app.<\/strong> Usually, unit tests are meant to only cover smaller chunks of code, leaving more complex scenarios to integration tests. These tests are meant to be run every time new changes are introduced, giving you clear signs if something broke in the process and needs to be fixed.<\/p>\n\n\n\n

Writing unit tests guarantees fewer complications in the future when you\u2019ll be shifting focus to other features. The more app\u2019s behavior you test, the less you\u2019ll have to worry when introducing new changes.\u00a0<\/p>\n\n\n\n

All of this is well-known in the software development industry, where practices like Test-Driven Development (TDD)<\/a> are widely adopted in agile teams. For example, TDD is a practice that focuses on writing unit tests even before implementing the actual code. This practice ensures that tests first fail, and then pass after writing the correct implementation.<\/p>\n\n\n\n

Django unit test – How to write and run tests?<\/h2>\n\n\n\n

For testing purposes, Django comes with a test framework that is built on top of the unittest<\/strong> module from Python\u2019s standard library. This module allows you to simulate and test all kinds of behaviors, such as receiving requests, validating permissions, submitting forms, querying the database, etc.<\/strong> <\/p>\n\n\n\n

NOTE<\/strong> - Django does not<\/strong> use your production database for testing. Also, you don\u2019t need to manually create a test database for the purpose of testing. Django will automatically create a temporary database and name it by adding the test_<\/strong> prefix to the NAME<\/strong> value from the DATABASES<\/strong> in settings.py<\/strong>.<\/pre>\n\n\n\n
Writing unit tests<\/h3>\n\n\n\n
To define a test case, create a file or set of files that will contain tests. Inside a test file, you can define multiple cases that need to be tested. Usually, each test case, which we can also call a Django unit test, contains multiple test methods that validate a specific behavior related to that case. To create an individual test case you have to derive a custom class from one of the Django test base classes<\/strong> (SimpleTestCase<\/code>, TransactionTestCase<\/code>, TestCase<\/code>, LiveServerTestCase<\/code>).<\/p>\n\n\n\n
One of the most commonly used base classes for testing is the django.test.TestCase<\/code> class. Test methods inside this class are run independently<\/strong>, but you can also define common behavior that should happen before and after running tests inside the setUpTestData<\/code>, setUp<\/code> and tearDown<\/code> methods.<\/p>\n\n\n\n
Validation inside the test methods is usually done with the help of Assert methods<\/a>. These methods are used to compare expected and obtained results. <\/p>\n\n\n\n
Let\u2019s take a look at the example of a simple test case defined inside the tests.py<\/code> file.<\/p>\n\n\n\n
from django.test import TestCase\n\nclass MyTestCase(TestCase):\n    @classmethod\n    def setUpTestData(cls):\n        # This method is run only once, before any other test.\n        # It's purpose is to set data needed on a class-level.\n        print('setUpTestData')\n\n    def setUp(self):\n        # This method is run before each test.\n        print('setUp')\n\n    def tearDown(self):\n        # This method is run after each test.\n        print('tearDown')\n\n    def test_my_first_method(self):\n        # This method should perform a test.\n        print('test_my_first_method')\n        self.assertTrue(True)\n\n    def test_my_second_method(self):\n        # This method should perform a test.\n        print('test_my_second_method')\n        self.assertFalse(True)<\/pre>\n\n\n\n
In the above example, we can notice a few important things.<\/p>\n\n\n\n
We created a MyTestCase<\/code> class that was derived from Django’s TestCase<\/code> class. Therefore, we got access to three additional methods:<\/p>\n\n\n\n