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tech_docs/python/pytest.md

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+`pytest` is an essential Python library for developers focused on testing their code. It provides a powerful yet simple framework for writing and running tests, supporting unit tests, functional tests, and more complex test scenarios. `pytest` stands out for its ease of use, detailed assertions, fixtures for setup and teardown, and support for parameterized testing, among other features. Here's a concise reference guide for common use cases with `pytest`:
+
+
+# `pytest` Reference Guide
+
+## Installation
+```
+pip install pytest
+```
+
+## Basic Usage
+
+### Writing Your First Test
+Tests are Python functions that start with `test_`. Place your test functions in files named `test_*.py` or `*_test.py`.
+
+```python
+# content of test_sample.py
+def func(x):
+    return x + 1
+
+def test_answer():
+    assert func(3) == 4
+```
+
+### Running Tests
+Navigate to the directory containing your test file and run:
+```
+pytest
+```
+`pytest` will discover and run all tests following its naming conventions.
+
+## Assertions
+`pytest` uses standard Python `assert` for verifying expectations and values in tests, providing detailed output on assertion failures.
+
+```python
+def test_check_equal():
+    assert func(4) == 5
+```
+
+## Fixtures
+Fixtures provide a powerful mechanism for setup and teardown operations, creating test data, and configuring the test environment.
+
+```python
+import pytest
+
+@pytest.fixture
+def input_value():
+    return 38
+
+def test_divisible_by_2(input_value):
+    assert input_value % 2 == 0
+```
+
+## Parameterized Tests
+Parameterize tests to run the same test function with different inputs.
+
+```python
+@pytest.mark.parametrize("test_input,expected", [(1, 2), (2, 3), (3, 4)])
+def test_eval(test_input, expected):
+    assert func(test_input) == expected
+```
+
+## Handling Exceptions
+Test that a certain exception is raised using the `pytest.raises` context manager.
+
+```python
+def test_exception():
+    with pytest.raises(ValueError):
+        raise ValueError
+```
+
+## Skipping Tests
+Skip a test function or expect it to fail.
+
+```python
+@pytest.mark.skip(reason="not implemented yet")
+def test_to_skip():
+    pass
+
+@pytest.mark.xfail
+def test_might_fail():
+    pass
+```
+
+## Using Plugins and Integrations
+`pytest` supports numerous plugins for integration with other tools and extending its functionality, such as `pytest-django` for Django projects, `pytest-asyncio` for testing asyncio code, and many more.
+
+## Configuration
+Use a `pytest.ini`, `tox.ini`, or `pyproject.toml` file to configure `pytest` behavior, like custom markers, test paths, and plugin configurations.
+
+## Advanced Usage
+`pytest` offers a broad spectrum of advanced features, including but not limited to test fixtures scopes, using mocks, and integrating with continuous integration (CI) tools.
+
+## Continuous Integration
+`pytest` can easily integrate with CI tools like Jenkins, GitHub Actions, or GitLab CI, running your test suite on every push or pull request automatically.
+
+`pytest` simplifies and accelerates the testing process, encouraging best practices in test writing and execution. Its extensive documentation and active community make it a go-to choice for Python developers looking to ensure their code meets the highest standards of quality.
+
+
+`pytest` is favored in the Python community for its rich ecosystem, simplicity, and ability to handle not just simple unit tests but also complex functional testing for applications and libraries.