Related objects, which can expose test flakiness around ordering (as the testĬonditional logic in tests - this is sometimes done to share some set-up Mock.patch (instead of ) is a smell of this problem.Ĭareless factory usage - beware of factories creating lots of unnecessary Of a unit being tested, not those further down the call chain. Mocking indirect collaborators - it's best to mock the direct collaborators Nested mocks - this indicates your unit under test know intimate detailsĪbout its collaborators (that it shouldn't know). Lots of mocks - this indicates your unit under test has to many It's tricky to configure Pytest fixtures and so it's best to inject a factoryįunction/class that can be called with configuration arguments. Using Pytest fixtures Shared fixturesįixtures defined in a conftest.py module can be used in several ways:Īpply to a single test by adding the fixture name as an argument.Īpply to every test in a class by decorating to every test in a module class by defining a module-level pytestmark Use -s to prevent output capturing - this is required for ipdb breakpoints Running tests Capturing outputĭefault is for pytest to capture but show output if the test fails. # Run command at a fixed point in time, specifying any relevant env vars. # tests/functional/test_command.py import main import time_machine def test_some_command( runner): Don't provide any values though - ensure tests specific # values relevant to them. # Provide a dictionary of environment variables so that configuration # parsing works. # tests/functional/conftest.py import pytest from click. Forĭjango model widgets, this is the PKs of the selected models: To fill in a multi-checkbox widget, assign a list of the values to select. Pass status="*" so 4XX or 5XX responses don't raise an exception. It provides a readable API for clicking on buttons and Exercise the system usingĪn external call (like a HTTP request) and only mock calls to externalĮnsure all relevant settings are explicitly defined in the test set-up. Strive to make the test as end-to-end as possible. Sleep well at night knowing that all your units are plumbed together correctly.įollow these patterns when writing functional tests:Įxplicitly comment each phase of a test to explain what is going on. That's ok - the value they provide is regression protection. High quality functional testsįunctional tests will necessarily be slow and fail with less-than-helpful error a session-scoped fixture for creating py.path.local temporaryĮnd-to-end tests that trigger the system by an external interface such as a HTTP a session-scoped fixture for creating pathlib.Path temporaryĪ function-scoped fixture for creating py.path.local temporary Pytest provides a few other fixtures for creating temporary files and folders: call_command( "import_csv_file", csv_file) # Call the management command passing the CSV filepath as an argument. # Create temporary CSV file csv_file = tmp_path / "temp.csv" with csv_file. management import call_command def test_csv_import( tmp_path): Note assert_has_calls shouldn't be used to check all calls to the spy as it assert_called_with (only checks the last call to the spy).That can be used to verify how a spy was called: Objects from Python's unittest.mock library provide several assert_called_with( x = 100)Īs you can see, the use of dependency injection in the first example leads to return_value = client # Here the client object is constructed from within the use case by calling # a `get_client` factory function. # Create spy and ensure factory function returns it. object( usecase, "get_client") def test_client_called_correctly( get_client): vendor import acme from foobar import usecase mock. When passing stubs as arguments to the target, preferįrom unittest import mock from foobar. You can specify its behaviour in advance. Stubbing involves replacing an argument or collaborator with your own version so Spys: where the mock calls are inspected after theĮquivalently you can think of mocks as either being actors (stubs) or critics Stubs: where the behaviour of the mock object is specified before the act This is useful for writing concise tests that pass a complex object as an input. # Named with trailing underscore as we can't use 'from' from_ = "Person" # Named with underscore as we can't use a hyphen is_nice = False class Meta: Creating Django model fixturesįor Django models, the basic pattern withĬlass AwkwardDict( factory. Tools and patterns for setting up the world how you want it (and cleaning upĪfterwards). Extracting information about how spy was called.Stubbing function calls that raise an exception.Value=factory.SelfAttribute('.project.This document is a reference for common testing patterns in a Django/Python I have the following ModelFactory: class ProjectDataModelFactory(DjangoModelFactory):
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