Understanding python.analysis.inlayHints.pytestParameters in Pylance

June 23, 2026 ยท View on GitHub

Pylance is a fast, feature-rich language server extension for Python in Visual Studio Code, powered by the Pyright static type checker. It provides type checking, completions, navigation, and inlay hints that help you understand your code at a glance.

The python.analysis.inlayHints.pytestParameters setting controls whether Pylance displays inferred types for pytest fixture parameters in test functions.

What python.analysis.inlayHints.pytestParameters does

When enabled, Pylance shows the inferred type of each pytest fixture parameter directly in the test function signature. This helps you understand what type each fixture provides without navigating to its definition.

The default value is false.

"python.analysis.inlayHints.pytestParameters": false

Example

Consider the following code:

import pytest

@pytest.fixture
def my_fixture():
    return "some data"

def test_something(my_fixture):
    assert my_fixture == "some data"

Without inlay hints, it is not immediately clear what type my_fixture holds. With python.analysis.inlayHints.pytestParameters set to true, Pylance displays:

def test_something(my_fixture: str):
    assert my_fixture == "some data"

The hint (: str) appears inline, showing the inferred fixture type at a glance.

Example with a complex fixture

import pytest

@pytest.fixture
def db_connection():
    return create_db_connection()

def test_query(db_connection):
    result = db_connection.execute("SELECT * FROM users")
    assert result is not None

With the setting enabled, Pylance displays the inferred type:

def test_query(db_connection: DatabaseConnection):
    result = db_connection.execute("SELECT * FROM users")
    assert result is not None

Accepted values

  • true: Enables inlay hints for pytest fixture parameters.
  • false (default): Disables inlay hints for pytest fixture parameters.

How to change the setting

To adjust this setting in Visual Studio Code:

  • Open Settings and search for python.analysis.inlayHints.pytestParameters.
  • Check or uncheck the box.

Alternatively, edit your settings.json file directly:

  • Open Command Palette, type Preferences: Open Settings (JSON), and select it.

  • Add or update the following line:

    "python.analysis.inlayHints.pytestParameters": true

Prerequisites

For pytest parameter inlay hints to work, the following must be true:

  • python.analysis.enablePytestSupport must be set to true (the default). This enables Pylance's pytest-specific features, including fixture resolution.
  • Fixtures must be defined using the @pytest.fixture decorator.
  • Test files should follow standard pytest naming conventions (test_*.py or *_test.py), and shared fixtures should be placed in conftest.py.

Limitations

  • Inferred types: Pylance infers types based on fixture return values. If a fixture returns a complex or dynamically typed value, the inferred type may be Any or less precise.
  • Performance: In large codebases with many fixtures, generating these hints requires additional analysis. If you notice slowdowns, consider disabling the feature.

Frequently asked questions

Q: Inlay hints are not showing for pytest parameters. What should I check?

A: Verify the following:

  • python.analysis.enablePytestSupport is set to true.
  • Your fixtures use the @pytest.fixture decorator.
  • Your test files follow standard pytest naming conventions (test_*.py or *_test.py).
  • Shared fixtures are in conftest.py.
  • You are using the latest version of Pylance.

Q: Will enabling this feature affect performance?

A: Enabling pytest parameter inlay hints may have a slight impact on performance in large codebases, as Pylance needs to analyze fixtures to determine their types. If you experience slowdowns, you can disable the feature.

Q: Do inlay hints modify my source code?

A: No. Inlay hints are visual annotations in the editor. They do not alter your source files.

For more information on Pylance settings and customization, refer to the Pylance Settings and Customization documentation.

This document was generated with the assistance of AI and has been reviewed by humans for accuracy and completeness.