deprecated_test.py

Overview

The [deprecated_test.py](/projects/286/67361) file contains a suite of automated tests focused on verifying the behavior of deprecated features, warnings, and APIs within the pytest framework and its related plugins. The primary goal of this file is to ensure that deprecated constructs in pytest, such as old plugin hooks, fixture usage patterns, and path handling, properly emit warnings or errors when used, thus guiding developers towards updated best practices.

This testing module helps maintain backward compatibility while encouraging migration away from deprecated features, supporting a smoother transition between pytest versions.

Detailed Explanations

Imports and Setup

• Standard libraries: pathlib.Path, re, sys

• Pytest internals and utilities: _pytest.deprecated, _pytest.compat.legacy_path, _pytest.pytester.Pytester

• pytest itself, including warning classes like PytestDeprecationWarning

Tests and Their Purpose

test_external_plugins_integrated(pytester: Pytester, plugin) -> None

• Purpose: Verifies that deprecated external plugins listed in deprecated.DEPRECATED_EXTERNAL_PLUGINS still integrate but emit a PytestConfigWarning.

• Parameters:

  • pytester: Pytest's test helper fixture for creating temporary test environments.

  • plugin: The name of each deprecated external plugin.

• Behavior:

  • Inserts the test directory in the system path.

  • Creates an empty Python file named after the plugin.

  • Parses the config with the plugin enabled, expecting a configuration warning.

• Usage Example:

def test_external_plugins_example(pytester: Pytester):
    # Example plugin name from the deprecated list
    plugin = "deprecated_plugin_name"
    pytester.syspathinsert()
    pytester.makepyfile(**{plugin: ""})
    with pytest.warns(pytest.PytestConfigWarning):
        pytester.parseconfig("-p", plugin)

test_hookspec_via_function_attributes_are_deprecated()

• Purpose: Ensures that defining hook specifications using function attributes (instead of decorators) triggers a PytestDeprecationWarning.

• Implementation Details:

  • Defines a class with a hook method decorated by setting a .historic attribute.

  • Adds the hookspecs to a PytestPluginManager instance.

  • Checks that a deprecation warning references the exact code line and file.

• Key Points:

  • Encourages using @pytest.hookspec(historic=False) decorator instead.

test_hookimpl_via_function_attributes_are_deprecated()

• Purpose: Validates that marking hook implementations with function attributes (e.g., .tryfirst = True) emits a deprecation warning.

• Implementation Details:

  • Defines a plugin class with a hook method, using attribute-based marker.

  • Registers the plugin on PytestPluginManager.

  • Asserts the warning is raised and points to the proper source code location.

• Encouraged Usage:

  • Use @pytest.hookimpl(tryfirst=True) instead of function attribute assignment.

test_yield_fixture_is_deprecated()

• Purpose: Confirms that using @pytest.yield_fixture raises a DeprecationWarning.

• Implementation Details:

  • Defines a simple yield fixture inside a warning context.

• Note: Modern pytest favors @pytest.fixture with yield instead of @yield_fixture.

test_private_is_deprecated()

• Purpose: Tests that instantiating a private pytest class or function without the _ispytest flag triggers a deprecation warning.

• Details:

  • Defines a class PrivateInit with a special _ispytest parameter checked by deprecated.check_ispytest.

  • Warning is raised if _ispytest is omitted or False.

• Usage:

  • Internal pytest code should pass _ispytest=True to suppress warnings.

  • External code should expect warnings when accessing private APIs.

test_hookproxy_warnings_for_pathlib(tmp_path, hooktype, request)

• Purpose: Tests that using deprecated py.path.local arguments in hook calls emits deprecation warnings, especially when mixing with pathlib.Path.

• Parameters:

  • tmp_path: pytest temporary path fixture.

  • hooktype: Either "hook" or "ihook" to test two hook proxy types.

  • request: pytest fixture that provides access to test context.

• Behavior:

  • Calls the hook pytest_ignore_collect with both deprecated path and new collection_path arguments.

  • Asserts warning is triggered and points to the correct source line.

  • Checks that mismatched path arguments raise a ValueError.

test_hookimpl_warnings_for_pathlib()

• Purpose: Checks that registering plugins with deprecated py.path.local arguments on hookimpl methods raise PytestRemovedIn9Warning.

• Details:

  • Defines a plugin class with multiple hookimpl methods expecting path arguments.

  • Registers the plugin to a PytestPluginManager.

  • Expects one warning per deprecated hookimpl method.

test_node_ctor_fspath_argument_is_deprecated(pytester: Pytester)

• Purpose: Verifies that passing fspath: py.path.local argument to node constructors (like pytest.File) emits a deprecation warning.

• Details:

  • Creates a subclass of pytest.File with a stub collect method.

  • Calls from_parent with a deprecated fspath argument.

  • Checks that a deprecation warning referencing the class name and argument is raised.

Tests for Fixture and Mark Warnings

These tests ensure that applying pytest marks (like `@pytest.mark.parametrize` or `@pytest.mark.usefixtures`) to fixtures or vice versa warns users because marks on fixtures currently have no effect, which may confuse users.

• test_fixture_disallow_on_marked_functions()

• test_fixture_disallow_marks_on_fixtures()

• test_fixture_disallowed_between_marks()

Each test:

• Defines a function with a combination of fixture and mark decorators in various orders.

• Asserts that PytestRemovedIn9Warning warnings are emitted.

• Checks the number of warnings and that they point to this test file.

Important Implementation Details and Algorithms

• The tests heavily utilize pytest.warns context managers to capture and assert specific deprecation warnings.

• Some tests introspect warnings to check source line numbers and filenames to ensure warnings point to correct user code locations.

• The legacy_path utility is used to simulate deprecated py.path.local instances.

• Several tests use parametrization and fixtures (pytester, tmp_path, request) to modularize and reuse test setups.

• The file does not define reusable classes or functions but rather a collection of test functions each targeting a specific deprecated feature or API.

Interactions within the System

• The tests depend on internal pytest modules such as _pytest.deprecated and _pytest.compat to identify deprecated APIs.

• They interact with Pytester to create isolated test environments for plugin and node testing.

• They verify behavior of PytestPluginManager for plugin registration and hook specification handling.

• The file helps ensure pytest core and plugin ecosystem maintain consistent deprecation policies.

• The tests indirectly affect development and maintenance workflows by validating that deprecation warnings are properly emitted, guiding developers away from outdated practices.

Visual Diagram: Class and Test Function Structure

flowchart TD
    A[test_external_plugins_integrated]
    B[test_hookspec_via_function_attributes_are_deprecated]
    C[test_hookimpl_via_function_attributes_are_deprecated]
    D[test_yield_fixture_is_deprecated]
    E[test_private_is_deprecated]
    F[test_hookproxy_warnings_for_pathlib]
    G[test_hookimpl_warnings_for_pathlib]
    H[test_node_ctor_fspath_argument_is_deprecated]
    I[test_fixture_disallow_on_marked_functions]
    J[test_fixture_disallow_marks_on_fixtures]
    K[test_fixture_disallowed_between_marks]

    subgraph Deprecated Features Tests
        A
        B
        C
        D
        E
        F
        G
        H
        I
        J
        K
    end

Summary

[deprecated_test.py](/projects/286/67361) is a critical test module within the pytest codebase that enforces correct deprecation behaviors. By systematically testing various deprecated APIs and usage patterns, it helps maintain the integrity and forward compatibility of pytest. This file's tests serve as both verification and documentation of deprecated features, ensuring developers receive clear guidance and warnings when using outdated constructs.

Additional Notes

• This file is mainly intended for pytest core developers and maintainers.

• It covers deprecated plugin loading, hook specification and implementation, fixture and mark usage, and path argument handling.

• No new features or production code is implemented here; it is purely a test suite for deprecation behaviors.

If you need further details on any specific test or pytest internals referenced here, please ask!