ipytest 0.9.0b1

Unit tests in IPython notebooks.

ipytest - Unit tests in IPython notebooks

Usage | Global state | Changes | Related packages | Reference | Development | License

Sometimes quick experiments in IPython grow large and you find yourself wanting unit tests. This module aims to make testing code in IPython notebooks easy. At its core, it offers a way to run pytest tests inside the notebook environment. It is also designed to make the transfer of the tests into proper python modules easy.

Installation: pip install ipytest

Features:

• support for pytest inside notebooks (with all bells and whistles)
• tight integration with IPython via magics and automatic code transforms

Usage

For usage see the example notebook or the documentation for the core API below.

The suggested way to import ipytest is:

import ipytest
ipytest.autoconfig()

Afterwards test in the current cell can be executed as in:

%%run_pytest[clean] -qq

def test_example():
    assert [1, 2, 3] == [1, 2, 3]

This command will first delete any previously defined tests, execute the cell and then run pytest. See the reference for a detailed list of available functionality.

Global state

There are two sources of global state when using pytest inside the notebook:

1. pytest will find any test function ever defined. This behavior can lead to unexpected results when test functions are renamed, as their previous definition is still available inside the kernel. ipytest ships the clean_test function to delete such instances. Also the %%run_pytest[clean] magic clears any previously defined tests.
2. Python's module system caches imports and therefore acts as a global state. To test the most recent version of any module, the module needs to be reloaded. ipytest offers the reload function. The autoreload extension of IPython may also help here. To test local packages, it is advisable to install them as development packages, e.g., pip install -e ..

Changes

Note: development is tracked on the develop branch.

• development:
  • Add Pytest>=5.4 to the requirements
  • Remove legacy functionality, mostly plain unittest integration
  • The tempfile_fallback also kicks in, if a filename was configured, but the file does not exist
  • Add register_module option to register the notebook with the module system of Python. This way --doctest-modules works as expected
• 0.8.1: release with sdist for conda-forge
• 0.8.0:
  • Add the autoconfig helper to simplfy setup with reasonable defaults
  • Stop using deprecated pytest API
• 0.7.1:
  • fix assertion rewriting for pytest>=5.0.0
• 0.7.0:
  • add option to run tests in separate threads. This change allows to test async code with the pytest_asyncio plugin
  • add a proper signature to ipytest.config(...) and show the current settings as a repr.
• 0.6.0: officially remove python 2 support. While ipytest was marked to work on python 2 and python 3, this statement was not tested and most likely not true. This change only documents the current state.
• 0.5.0:
  • Fix assertion rewriting via magics in ipython>=7
  • Add support to raise a RuntimeError on test errors (set ipytest.config.raise_on_error = True)
  • Add support to set base arguments (set ipytest.config.addopts = [])
  • Add config setting to enable magics (set ipytest.config.magics = True).
  • Add config setting to create a temporary file to work without the notebook filename (set ipytest.config.tempfile_fallback = True).
  • Allow to set multiple config values at the same time by calling the config object (ipytest.config(...)).
  • Add ipytest.running_as_test() to detect whether a notebook is executed as a test.
• 0.4.0: add support for automatic AST transforms, deprecate non pytest API.
• 0.3.0: change default pattern for clean_tests to match pytest discovery
• 0.2.2: add support for assert rewriting with current pytest versions
• 0.2.1: add ipython magics to simplify test execution
• 0.2.0: support for using pytest inside notebooks
• 0.1.0: support for running unittest.FunctionTestCase, unittest.TestCases, and doctests.

Related packages

ipytest is designed to enable running tests within an interactive notebook session. There are also other packages that aim to use notebooks as tests themselves, for example by comparing the output of running all cells to the output of previous runs. These packages include:

• nbval is actively maintained. It is also used in the integration tests of ipytest.
• pytest-ipynb seems to be no longer maintained as the latest commit was on March 2016. .
• ...

Please create an issue, if I missed a packaged or mischaracterized any package.

Reference

ipytest.autoconfig

ipytest.autoconfig(rewrite_asserts=<default>, magics=<default>, tempfile_fallback=<default>, clean=<default>, addopts=<default>, raise_on_error=<default>, run_in_thread=<default>, register_module=<default>)

Configure ipytest with reasonable defaults.

Specifically, it sets:

• rewrite_asserts: True
• magics: True
• tempfile_fallback: True
• clean: '[Tt]est*'
• addopts: ('-q',)
• raise_on_error: False
• run_in_thread: False

See ipytest.config for details.

%%run_pytest ...

IPython magic that first executes the cell, then executes ipytest.run(). Any arguments passed on the magic line be passed on to pytest. To register the magics, run ipytest.config.magics = True first.

For example:

%%run_pytest -qq


def test_example():
    ...

%%run_pytest[clean] ...

Same as the %%run_pytest, but cleans any previously found tests, i.e., only tests defined in the current cell are executed. To register the magics, run ipytest.config.magics = True first.

ipytest.config

Configure ipytest. The following settings are suported:

• ipytest.config.rewrite_asserts (default: False): enable ipython AST transforms globally to rewrite asserts.
• ipytest.config.magics (default: False): if set to True register the ipytest magics.
• ipytest.config.clean (default: [Tt]est*): the pattern used to clean variables.
• ipytest.config.addopts (default: ()): pytest command line arguments to prepend to every pytest invocation. For example setting ipytest.config.addopts= ['-qq'] will execute pytest with the least verbosity.
• ipytest.config.raise_on_error (default: False): if True, unsuccessful invocations will raise a RuntimeError.
• ipytest.config.tempfile_fallback (default: False): if True, a temporary file is created as a fallback when no valid filename can be determined.
• ipytest.config.run_in_thread (default: False): if True, pytest will be run a separate thread. This way of running is required when testing async code with pytest_asyncio since it starts a separate event loop.
• ipytest.register_module (default: False): if True, ipytest will register the notebook with Python module system. This way the module can be imported. Some pytest plugins require importing the module. An eample is the doctest module. It is strongly recommeneded to only use register_module=True with the tempfile_fallback, since otherwise real modules may be shadowed.

To set multiple arguments at once, the config object can also be called, as in:

ipytest.config(rewrite_asserts=True, raise_on_error=True)

ipytest.exit_code

The return code of the last pytest invocation.

ipytest.run

ipytest.run(*args, module=None, filename=None, plugins=(), return_exit_code=False)

Execute all tests in the passed module (defaults to main) with pytest.

Parameters

• args (any): additional commandline options passed to pytest
• module (any): the module containing the tests. If not given, main will be used.
• filename (any): the filename of the file containing the tests. It has to be a real file, e.g., a notebook name, since itts existence will be checked by pytest. If not given, the file attribute of the passed module will be used.
• plugins (any): additional plugins passed to pytest.

ipytest.clean_tests

ipytest.clean_tests(pattern=None, items=None)

Delete tests with names matching the given pattern.

In IPython the results of all evaluations are kept in global variables unless explicitly deleted. This behavior implies that when tests are renamed the previous definitions will still be found if not deleted. This method aims to simply this process.

An effecitve pattern is to start with the cell containing tests with a call to clean_tests, then defined all test cases, and finally call run_tests. This way renaming tests works as expected.

Arguments:

• pattern: a glob pattern used to match the tests to delete.
• • items: the globals object containing the tests. If None is given, the: globals object is determined from the call stack.

ipytest.reload

ipytest.reload(*mods)

Reload all modules passed as strings.

This function may be useful, when mixing code in external modules and notebooks.

Usage:

reload("ipytest._util", "ipytest")

ipytest.running_as_test

ipytest.running_as_test()

Check whether the notebook is executed as a test.

This function may be useful, when running notebooks as integration tests to ensure the runtime is not exceedingly long.

Usage:

model.fit(x, y, epochs=500 if not ipytest.running_as_test() else 1)

%%rewrite_asserts

Rewrite any asserts in the current cell using pytest without running the tests. To get best results run the tests with run. To register the magics, run ipytest.config.magics = True first.

For example::

%%rewrite_asserts

def test_example():
    ...

Development

To execute the unit tests of ipytest run

pipenv sync --dev
pipenv run test

Before commit execute pipenv run precommit to update the documentation, format the code, and run tests.

To create a new release execute:

pipenv run release

License

The MIT License (MIT)
Copyright (c) 2015 - 2020 Christopher Prohm

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
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and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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