Python FASTAPI Testing - Revision history

Iwiseman: /* Replacing Dependencies */

2026-06-04T20:44:28Z

Replacing Dependencies

← Older revision		Revision as of 20:44, 4 June 2026
Line 138:		Line 138:

	This ensures every test receives the fake dependency instead of the real one.		This ensures every test receives the fake dependency instead of the real one.
			=Fixtures and Yield=
			If you use fixtures with yield pytest re-implements yield and adds a try, finally around the yield to ensure the takedown occurs.
			<syntaxhighlight lang="py">
			import pytest

			state = {"cleaned": False}

			@pytest.fixture
			def f():
			print("SETUP")
			# Implemented by pytest
			# try:
			yield
			# finally
			print("TEARDOWN")
			state["cleaned"] = True

			def test_fail(f):
			print("TEST BODY")
			raise RuntimeError("boom")
			</syntaxhighlight>

2026-06-04T01:40:17Z

Fixtures

@@ Line 77: / Line 77: @@
 <br>
 The second sets the class property encryptor for module user_management.password_manager to the result of get_encryptor(EncryptorNames.ARGON2).
 =Replacing Dependencies=

2026-06-04T01:07:23Z

Fixtures

← Older revision		Revision as of 01:07, 4 June 2026
Line 77:		Line 77:
	<br>		<br>
	The second sets the class property encryptor for module user_management.password_manager to the result of get_encryptor(EncryptorNames.ARGON2).		The second sets the class property encryptor for module user_management.password_manager to the result of get_encryptor(EncryptorNames.ARGON2).
			=Replacing Dependencies=

			FastAPI allows you to replace dependencies during testing.
			This is done using a special dictionary on the FastAPI app:

			<syntaxhighlight lang="py">
			app.dependency_overrides[original_dependency] = replacement_dependency
			</syntaxhighlight>

			FastAPI checks this dictionary at request time.
			If an override exists, FastAPI calls the replacement instead of the real dependency.

			This lets you “fake” authentication, database access, or any other dependency.

			Example:

			<syntaxhighlight lang="py">
			@pytest.fixture(autouse=True)
			def override_thing_dependency():
			def fake_thing():
			class FakeThing:
			def skip_thing_function(self):
			pass
			return FakeThing()

			# Replace the real dependency with our fake version
			app.dependency_overrides[thing_injected] = fake_thing

			# After the test, restore the original dependency
			yield
			app.dependency_overrides.pop(thing_injected, None)
			</syntaxhighlight>

			This ensures every test receives the fake dependency instead of the real one.

2026-06-03T23:31:04Z

Fixtures

← Older revision		Revision as of 23:31, 3 June 2026
Line 74:		Line 74:
	monkeypatch.setattr(user_management.password_manager, "encryptor", get_encryptor(EncryptorNames.ARGON2))		monkeypatch.setattr(user_management.password_manager, "encryptor", get_encryptor(EncryptorNames.ARGON2))
	</syntaxhighlight>		</syntaxhighlight>
			The first sets variable authentication_encryptor in the module settings to the Enum EncryptorNames.ARGON2.value<br>
			<br>
			The second sets the class property encryptor for module user_management.password_manager to the result of get_encryptor(EncryptorNames.ARGON2).

2026-06-03T23:26:01Z

Comparison to Jest

@@ Line 1: / Line 1: @@
 =Introduction=
 This page is to capture how to go about testing with FAST API
 =Comparison to Jest=
 Here is a table to help compare terminology
@@ Line 32: / Line 64: @@
 | Fixtures returning objects
 |}
 =Fixtures=
 These are things you create to set up a test. The autouse means you do not need to pass the fixture to the tests.

2026-06-03T23:12:33Z

Comparison to Jest

← Older revision		Revision as of 23:12, 3 June 2026
Line 32:		Line 32:
	\| Fixtures returning objects		\| Fixtures returning objects
	\|}		\|}
			=Fixtures=
			These are things you create to set up a test. The autouse means you do not need to pass the fixture to the tests.
			<syntaxhighlight lang="py">
			# Force argon2 for testing purposes
			@pytest.fixture(autouse=True)
			def force_argon2(monkeypatch: pytest.MonkeyPatch):
			monkeypatch.setattr(settings, "authentication_encryptor", EncryptorNames.ARGON2.value)
			monkeypatch.setattr(user_management.password_manager, "encryptor", get_encryptor(EncryptorNames.ARGON2))
			</syntaxhighlight>

2026-06-03T22:59:50Z

Introduction

← Older revision		Revision as of 22:59, 3 June 2026
Line 1:		Line 1:
	=Introduction=		=Introduction=
	This page is to capture how to go about testing with FAST API		This page is to capture how to go about testing with FAST API
			=Comparison to Jest=
			Here is a table to help compare terminology
			{\| class="wikitable"
			! Concept
			! Jest
			! pytest
			\|-
			\| Test setup
			\| <code>beforeEach</code>, <code>beforeAll</code>
			\| Fixtures (function, module, session scope)
			\|-
			\| Test teardown
			\| <code>afterEach</code>, <code>afterAll</code>
			\| Fixture finalizers / yield fixtures
			\|-
			\| Dependency injection
			\| Manual mocks, passing objects
			\| Fixture injection by name
			\|-
			\| Auto‑applied setup
			\| Global <code>beforeEach</code> in setup files
			\| <code>@pytest.fixture(autouse=True)</code>
			\|-
			\| Mocking
			\| <code>jest.mock</code>, <code>jest.spyOn</code>
			\| <code>monkeypatch.setattr</code>, <code>unittest.mock.patch</code>
			\|-
			\| Test data factories
			\| Helper functions
			\| Fixtures returning objects
			\|}

2026-06-03T22:55:01Z

Created page with "=Introduction= This page is to capture how to go about testing with FAST API"

New page

=Introduction=
This page is to capture how to go about testing with FAST API