yourbase 5.2.0

Skip tests based on tracing data

YourBase Python Test Acceleration

Tests are important. For large monoliths, they're also a major source of drag on velocity.

YourBase is a tool that traces your tests to determine which functions each test depends on in order to create a dependency graph. It can later use the dependency graph to determine which tests don't need to run because their code paths have not changed. These tests are skipped automatically.

No configuration, setup, or babysitting required. All you need is

pip install yourbase

YourBase works with Python 2.7+ and Python 3.5+; using pytest or unittest.

Access

By using YourBase, you agree to our terms of service.

YourBase will work for free locally for 30 days. Please consider purchasing a license if you like it -- those who do generally get more back than they spend.

A license also lets YourBase work in your CI, and synchronize its dependency graph among an arbitrary number of machines (without leaving your network).

First run

After installing yourbase, if you are using unittest you must put

import unittest
import yourbase

yourbase.attach(unittest)

in a file that runs before your tests (e.g. tests/__init__.py). Do not do this step if you are using pytest.

Run your tests with the same command you typically use. You should see some output from YourBase similar to

[YB] Starting Python acceleration

The first run will be cold. During a cold run, YourBase will build a dependency graph base on the tests that are executed. The graph contains relationships between individual tests and the functions they call. If you just want to see YourBase in action and your tests are going to take a while, you can run a subset of tests. The dependency graph for the subset will be used correctly even if you later run all tests.

After the run finishes, running again will skip all tests. Modifying a dependency will run only tests whose code paths touched the changed code. You're YourBased! 🚀

Forcing specific tests to run

You can tell YourBase to never skip specific tests with decorators:

# pytest
import pytest

@pytest.mark.do_not_accelerate
def test_function():
   # ...

# unittest
import yourbase.plugins.unittest as yourbase

@yourbase.do_not_accelerate
class TestClass(unittest.TestCase):
   def test_function():
      # ...

The test or group will never be skipped due to unchanged dependencies. If you are using test cohorting (below), it may still be skipped if it is not assigned to the running shard.

We do not yet support this feature for unittest.

How do I know YourBase won't incorrectly skip important tests?

YourBase test selection includes an "observation mode" which allows you to test drive test selection without actually skipping any tests. "Observation mode" provides feedback to help you establish trust between your test suite and the test selection plugin.

In “observation mode” all [command-line specified] examples will be run, but YourBase will monitor if the test selection would have skipped any examples that ultimately failed. At the end, it will print out the names of any tests that would have been incorrectly skipped.

To enable observation mode, set YOURBASE_OBSERVATION_MODE=true in the environment, and run your specs.

# Pytest example
$ YOURBASE_OBSERVATION_MODE=true pytest tests/

Synchronizing dependency graphs

By default, YourBase's dependency graph is stored locally on the machine where it was created and will not leave the machine without further configuration. While local test acceleration is great for your individual needs, the true power comes in sharing graphs with individuals, teams, and CI environments.

The dependency graph data includes:

• test names
• file names
• class and function names
• relationships between of the above
• a small amount of metadata like commit hash, build time, and Python version

To share dependency graphs, YourBase utilizes an S3 bucket as a collaboration point.

AWS S3 bucket configuration

All machines should set

YOURBASE_REMOTE_CACHE=s3://<bucketname>[/key/prefix]

where <bucketname> is an S3 bucket that each machine has Get/Put/List access to. Dependency graphs generated for passing builds from clean working trees will be synchronized to this location, then used for future runs if a local cache is not present.

It is safe to share one bucket between multiple repositories, even if across multiple languages.

YourBase uses the system AWS credentials by default. This can be configured via environment variables or AWS CLI configuration files.

# To use system AWS credentials via environment variables, ensure your
# credentials are exported in your environment.
export AWS_ACCESS_KEY_ID=changeme
export AWS_SECRET_ACCESS_KEY=changeme

If you're setting the system AWS credentials to bogus values for your tests or CI, you can set these YourBase-specific environment variables instead:

# To set YourBase specific AWS credentials, export the following:
export YOURBASE_AWS_ACCESS_KEY_ID=changeme
export YOURBASE_AWS_SECRET_ACCESS_KEY=changeme

If these are set, we'll use them instead of the system credentials.

Your code base will never be uploaded to the bucket. Neither your code nor your dependency graphs will touch YourBase servers.

Test parallelization

YourBase has first-party support for acceleration-friendly parallelization:

1. Set YOURBASE_COHORT_COUNT to the number of shards
2. Set YOURBASE_ACTIVE_COHORT to the shard ID (in the range [1, YOURBASE_COHORT_COUNT])

YourBase uses consistent hashing to split your tests across shards so they do not get "reshuffled" when other tests are added or removed. This will give parallelized tests the full benefits of acceleration.

CircleCI users do not have to set the above environment variables as YourBase will inherit them automatically. However you must remove any CircleCI test splitting or globbing, as YourBase will automatically choose which tests to run "just in time".

Compatibility

Poetry

YourBase is compatible with the packaging and dependency management tool Poetry. Once the YourBase package is installed, simply use Poetry as normally.

For example:

# Install the YourBase package
poetry add yourbase

# Execute tests
poetry run pytest

Known issues

Incorrectly skipped tests

If you are using unittest and define your own setUp/tearDown functions, be sure they call super before performing other actions:

class MyTestClass:
   def setUp(self):
      super(self.__class__, self).setUp()
      # ...

   def tearDown(self):
      super(self.__class__, self).tearDown()
      # ...

If you are not defining your own setUp and tearDown functions, you do not need to do this.

Errors

If you run into errors about the _sqlite3 module not being found, first run

# Debian-based
sudo apt-get install libsqlite3-dev
# macOS
brew install sqlite3

then rebuild and reinstall the Python version you are using. If you use pyenv, this will look something like

pyenv install --force <PYTHON_VERSION>

# If that doesn't work, try
PYTHON_CONFIGURE_OPTS="--enable-loadable-sqlite-extensions" pyenv install --force <PYTHON_VERSION>

Conflicts

Coverage.py's dynamic_context option

YourBase has a tracing conflict with one particular config setting in your .coveragerc:

[run]
dynamic_context = test_function

If this specific key is set to this specific value, YourBase will "miss" some functions when tracing tests, causing its subsequent runs to skip tests that should not be skipped.

You can work around this by either unsetting the option, or by enabling YourBase's experimental line-granularity tracing, which does not conflict with this setting:

export YOURBASE_TRACING_TYPE=line

Although this circumvents the issue, this tracing type is in early stages and is less stable than function-granularity tracing (the default).

If you do not have this specific setting set in your .coveragerc or in Coverage.py's command line arguments, you do not have to worry about this issue.

Proxy objects

Python objects that opaquely wrap other objects by overriding Python builtins like __name__ and __class__ can cause tracing issues in YourBase that may manifest as errors from within those proxy objects. If you experience these issues, you can set

export YOURBASE_TIMID=true

to use a slower tracing algorithm that will avoid these errors. Tracing overhead is dramatically increased using this flag, so we don't recommend setting this if you are not experiencing issues.

Plugin pytest-xdist

The YourBase Test Selection and pytest-xdist plugins have similar goals, reducing the overall test execution time of tests but take different approaches to solving the problem. As such, there are conflicts when both plugins are enabled. When using the YourBase Test Selection plugin, please uninstall pytest-xdist or execute pytest-xdist with NUMCPUS=0.

Changelog

• 5.2.0 (2021-05-28)
  • Adds observation mode
  • Adds optional anonymized telemetry
• 5.1.6 (2021-05-26)
  • Improves documentation
  • Improves log output
  • Fixes a bug where blank/absent/unreadable file paths for Python code would cause an error when traced
  • Fixes a bug where a remote dependency graph could be found and selected, but not used
  • In pytest, tests not run due to cohorting are now deselected (changed from selected but skipped)
  • Improved error handling in the face of pytest-xdist
  • Fixes a bug where a pytest run that selected 0 tests would be interpreted as failed
  • Fixes a bug where attaching to unittest hooks then using pytest to run a unittest.TestCase test would error
  • Standardizes terminology to "dependency graph" over "tracing data"
• 5.1.5 (2021-05-18)
  • When debug mode is on, debug output is now sent to both stdout and file (changed from just file)
• 5.1.4 (2021-05-18)
  • Fixes a bug with unittest support that could cause blank tracing data
  • Fixes a bug with unittest support that could cause tracing data to be written even for failed tests
• 5.1.3 (2021-05-18)
  • Fixes an error condition if pytest isn't installed
• 5.1.2 (2021-05-17)
  • Fixes CircleCI sharded environments from not being inherited by YourBase correctly
• 5.1.1 (2021-05-17)
  • Adds first-party support for test parallelization
• 5.0.10 (2021-05-13)
  • Fixes a compatibility issue with Celery
  • Fixes a compatibility issue with "proxy objects" causing tests to error
  • Improves error messages related to Git availability
• 5.0.9 (2021-05-11)
  • Fixes an issue processing certain styles of PEP 263 tags (e.g. # -*- coding: utf-8 -*-)
  • Adds some friendlier error messages and/or fallbacks caused by Git issues
• 5.0.7 (2021-05-06)
  • Fixes a JSON decoding issue present in Python 3.5
  • Fixes a breaking bug when YourBase is enabled alongside tests that use moto mocks