pytest and unittest are two commonly used testing frameworks in Python, both of which can be used to write and execute test cases, but they are different in many ways. This article will discuss these differences from different perspectives to help you better understand pytest and unittest.
1. Principle
pytest is a test framework based on Python's assert statement and Python's introspection feature. Its principle is to test Python functions based on decorators.
unittest is a test framework based on the Java-based JUnit test framework. Its principle is object-oriented design, and test cases need to be encapsulated in test classes for testing.
2. Support functions
Pytest support functions:
1) Multiple assertion styles, such as assert, assertion, expect and should;
2) Use standard output to output test results;
3) Customize plug-ins to extend the functions of the test framework, such as supporting test reports, test coverage, performance testing, etc.;
4) Use fixtures to manage dependencies of test cases;
5) Support the use of pytest-xdist plug-ins for distributed testing;
unittest support functions:
1) Test suites and test devices, such as using setUp() and tearDown() methods to initialize and clean up the test environment;
2) Support multiple assertion methods, such as assertEqual, assertNotEqual, assertTrue, assertFalse;
3) Use TestResult and TestSuite to manage the execution order of test results and test cases;
4) Support unittest.mock to simulate and replace test objects;
5) Support coverage.py for test coverage analysis;
6) Support generating test reports in HTML format;
3. Use case composition
pytest uses Python functions to write test cases. The name of the test case starts with test_, and the parameters of the test case are managed by fixtures.
unittest uses Python classes to write test cases. The name of the test case starts with test, and the test case needs to inherit the unittest.TestCase class.
4. Running mode
pytest supports running test cases from command line, text file or Python module, and will automatically collect test case execution when the test is running.
unittest needs to encapsulate the test case in the test class, and run the test case through the command line or the test runner. When the test is running, it needs to manually specify the test class or test method for execution. It supports the use of python -m unittest to execute the test case.
5. Extensibility
pytest can flexibly customize plug-ins to extend the functions of the test framework, and can easily integrate with other Python libraries and tools, such as using with Selenium, Requests, BeautifulSoup and other libraries for end-to-end testing, API testing, web testing, etc.
unittest can also extend the function of the test framework by customizing the test runner and test device, but compared with pytest, the flexibility is lower. The scalability of unittest is mainly reflected in the support of using libraries such as mock and coverage.py for test extension .
6. Parameterized
pytest supports the use of fixtures to manage the parameters of test cases, and supports the use of @pytest.mark.parametrize for parameterized tests.
unittest supports the use of the setUp() method to initialize test cases, and supports the use of TestCase.subTest for parameterized testing, but it is more troublesome than pytest.
7. Test report
pytest supports the use of pytest-html plug-in or pytest-xdist plug-in to generate test reports, which can generate test reports in HTML format, including test results, test cases, test coverage and other information, which can be easily analyzed and Check.
unittest supports using libraries such as coverage.py and unittest-xml-reporting to generate test reports, but it is not as convenient as pytest to generate test reports.
8. Ease of use
Compared with unittest, pytest is easier to use. Its test cases can be written using simple Python functions. It supports 3 operation modes, and it is relatively simple to write and execute.
unittest needs to encapsulate the test case in the test class, and the test class or test method needs to be manually specified for execution when the test is running. unittest is more stable and mature than pytest, but less scalable.
9. Applicable scenarios
pytest is suitable for projects that require unit testing, integration testing, and end-to-end testing, especially for projects with a large number of test cases.
unittest is suitable for projects that require unit testing and integration testing, especially for relatively simple test cases.
Both pytest and unittest are commonly used testing frameworks in Python, and they each have their own advantages and applicable scenarios. If you are not familiar with the Python testing framework, it is recommended to start with unittest first, and then gradually understand pytest after you are familiar with it.