pytest-print

Common errors

• fixture 'printer' not found

  cause The `pytest-print` plugin is not installed in the active Python environment or pytest is not discovering plugins correctly.
  fix Ensure `pytest-print` is installed via `pip install pytest-print` in the same environment where `pytest` is being run. Verify `pytest` itself is correctly installed and accessible.

• My `print()` statements aren't showing up during tests, but `printer()` output does.

  cause pytest captures standard output and error by default. The `printer` and `pprint` fixtures explicitly bypass this capture, which is their intended behavior.
  fix If you want standard `print()` statements to appear during test execution, run `pytest` with the `-s` flag (e.g., `pytest -s`). Alternatively, use the `printer` fixture for all direct terminal output you wish to always see.

Warnings

• breaking pytest-print v1.2.0 dropped support for Python 3.8 and 3.9. Subsequent versions, including 1.2.2, require Python >=3.10.
  Fix: Upgrade your Python environment to 3.10 or newer, or pin pytest-print to a version less than 1.2.0 if you must use older Python versions (e.g., `pytest-print<1.2.0` for Python 3.9).
• gotcha The `printer` and `pprint` fixtures bypass pytest's standard stdout/stderr capture mechanisms to ensure output is always visible in the terminal. This can be confusing if you expect all `print()` statements to behave similarly.
  Fix: Use `printer()` or `pprint()` when you specifically need output to appear immediately on the terminal regardless of pytest's capture settings. For regular `print()` statements, either run pytest with `-s` (or `--capture=no`), or expect them to be captured and displayed only on test failure or with specific `--show-capture` options.
• breaking Version 1.2.1 included internal modernizations for Python 3.10+ and public pytest APIs. While not typically affecting end-user tests directly, this may subtly break compatibility for advanced users or other plugins relying on specific internal behaviors of `pytest-print` prior to this version.
  Fix: Ensure your testing environment is on Python 3.10+ and that any custom integrations or plugins are tested against `pytest-print` 1.2.1 or newer. Consult `pytest`'s public API for best practices.

Install

• pip install pytest-print Install pytest-print

Imports

• printer
  wrong:

  from pytest_print import printer

  correct:

  def test_example(printer):

  The 'printer' fixture is automatically discovered by pytest and injected into test functions; no explicit import statement is typically needed in test files.
• pprint
  wrong:

  from pytest_print import pprint

  correct:

  def test_example(pprint):

  The 'pprint' fixture is automatically discovered by pytest and injected into test functions for pretty-printing data.
• printer_factory
  wrong:

  from pytest_print import printer_factory

  correct:

  def test_example(printer_factory):

  The 'printer_factory' fixture provides a callable to create custom printer instances.

Quickstart

Demonstrates the use of the `printer` and `pprint` fixtures to output messages directly to the terminal during a pytest run, bypassing standard capture. Note the recommendation to use `-s` for `print()` output to appear.

import pytest

def test_printer_fixture(printer):
    # The 'printer' fixture writes directly to the terminal, bypassing pytest's stdout capture.
    printer("Hello from pytest-print! This message should always appear.")
    print("This is a standard print. It will be captured unless pytest is run with -s.")

def test_pprint_fixture(pprint):
    data = {'name': 'Alice', 'age': 30, 'cities': ['New York', 'London']}
    pprint(data)
    pprint([1, 2, 3, {'a': 'b', 'c': 'd'}])

# To run this test:
# 1. Save as a Python file (e.g., test_my_app.py)
# 2. Run from your terminal in the same directory: pytest -v -s test_my_app.py