V2: new tox multi-dimensional, platform-specific configuration¶
Note
This is a draft document sketching a to-be-done implementation. It does not fully specify each change yet but should give a good idea of where things are heading. For feedback, mail the testing-in-python mailing list or open a pull request on https://github.com/tox-dev/tox/blob/master/doc/config-v2.txt
Abstract: Adding multi-dimensional configuration, platform-specification and multiple installers to tox.ini.
Target audience: Developers using or wanting to use tox for testing their python projects.
Issues with current tox (1.4) configuration¶
Tox is used as a tool for creating and managing virtualenv environments and running tests in them. As of tox-1.4 there are some issues frequently coming up with its configuration language:
- there is no way to instruct tox to parametrize testenv specifications
other than to list all combinations by specifying a
[testenv:...]
section for each combination. Examples of real life situations arising from this: - there is no way to have platform specific settings other than to define specific testenvs and invoke tox with a platform-specific testenv list.
- there is no way to specify the platforms against which a project shall successfully run.
- tox always uses pip for installing packages currently. This has
several issues:
- no way to check if installing via easy_install works
- no installs of packages with compiled c-extensions (win32 standard)
Goals, resolving those issues¶
This document discusses a possible solution for each of these issues, namely these goals:
- allow to more easily define and run dependency/interpreter variants with testenvs
- allow platform-specific settings
- allow to specify platforms against which tests should run
- allow to run installer-variants (easy_install or pip, xxx)
- try to mimick/re-use bash-style syntax to ease learning curve.
Example: Generating and selecting variants¶
Suppose you want to test your package against python2.6, python2.7 and on the
windows and linux platforms. Today you would have to
write down 2*2 = 4 [testenv:*]
sections and then instruct
tox to run a specific list of environments on each platform.
With tox-1.X you can directlys specify combinations:
# combination syntax gives 2 * 2 = 4 testenv names
#
envlist = {py26,py27}-{win,linux}
[testenv]
deps = pytest
platform =
win: windows
linux: linux
basepython =
py26: python2.6
py27: python2.7
commands = pytest
Let’s go through this step by step:
envlist = {py26,py27}-{windows,linux}
This is bash-style syntax and will create 2*2=4
environment names
like this:
py26-windows
py26-linux
py27-windows
py27-linux
Our [testenv]
uses a new templating style for the platform
definition:
platform=
windows: windows
linux: linux
These two conditional settings will lead to either windows
or
linux
as the platform string. When the test environment is run,
its platform string needs to be contained in the string returned
from platform.platform()
. Otherwise the environment will be skipped.
The next configuration item in the testenv
section deals with
the python interpreter:
basepython =
py26: python2.6
py27: python2.7
This defines a python executable, depending on if py26
or py27
appears in the environment name.
The last config item is simply the invocation of the test runner:
commands = pytest
Nothing special here :)
Note
Tox provides good defaults for platform and basepython settings, so the above ini-file can be further reduced:
[tox]
envlist = {py26,py27}-{win,linux}
[testenv]
deps = pytest
commands = pytest
Voila, this multi-dimensional tox.ini
configuration
defines 2*2=4 environments.
The new “platform” setting¶
A testenv can define a new platform
setting. If its value
is not contained in the string obtained from calling
sys.platform
the environment will be skipped.
Expanding the envlist
setting¶
The new envlist
setting allows to use {}
bash-style
expressions. XXX explanation or pointer to bash-docs
Templating based on environments names¶
For a given environment name, all lines in a testenv section which
start with “NAME: ...” will be checked for being part in the environment
name. If they are part of it, the remainder will be the new line.
If they are not part of it, the whole line will be left out.
Parts of an environment name are obtained by -
-splitting it.
Variant specification with [variant:VARNAME]
Showing all expanded sections¶
To help with understanding how the variants will produce section values, you can ask tox to show their expansion with a new option:
$ tox -l [XXX output ommitted for now]
Making sure your packages installs with easy_install¶
The new “installer” testenv setting allows to specify the tool for installation in a given test environment:
[testenv]
installer =
easy: easy_install
pip: pip
If you want to have your package installed with both easy_install and pip, you can list them in your envlist likes this:
[tox]
envlist = py[26,27,32]-django[13,14]-[easy,pip]
If no installer is specified, pip
will be used.
Use more bash-style syntax¶
tox leverages bash-style syntax if you specify mintoxversion = 1.4:
- $VARNAME or ${...} syntax instead of the older {} substitution.
- XXX go through config.txt and see how it would need to be changed
Transforming the examples: django-rest¶
The original django-rest-framework tox.ini file has 159 lines and a lot of repetition, the new one would +have 20 lines and almost no repetition:
[tox]
envlist = {py25,py26,py27}-{django12,django13}{,-example}
[testenv]
deps=
coverage==3.4
unittest-xml-reporting==1.2
Pyyaml==3.10
django12: django==1.2.4
django13: django==1.3.1
# some more deps for running examples
example: wsgiref==0.1.2
example: Pygments==1.4
example: httplib2==0.6.0
example: Markdown==2.0.3
commands =
!example: python setup.py test
example: python examples/runtests.py
Note that {,-example}
in the envlist denotes two values, an empty
one and a example
one. The empty value means that there are no specific
settings and thus no need to define a variant name.
Transforming the examples: django-treebeard¶
Another tox.ini has 233 lines and runs tests against multiple Postgres and Mysql engines. It also performs backend-specific test commands, passing different command line options to the test script. With the new tox-1.X we not only can do the same with 32 non-repetive configuration lines but we also produce 36 specific testenvs with specific dependencies and test commands:
[tox]
envlist =
{py24,py25,py26,py27}-{django11,django12,django13}-{nodb,pg,mysql}, docs
[testenv:docs]
changedir = docs
deps =
Sphinx
Django
commands =
make clean
make html
[testenv]
deps=
coverage
pysqlite
django11: django==1.1.4
django12: django==1.2.7
django13: django==1.3.1
django14: django==1.4
nodb: pysqlite
pg: psycopg2
mysql: MySQL-python
commands =
nodb: {envpython} runtests.py {posargs}
pg: {envpython} runtests.py {posargs} \
--DATABASE_ENGINE=postgresql_psycopg2 \
--DATABASE_USER=postgres {posargs}
mysql: {envpython} runtests.py --DATABASE_ENGINE=mysql \
--DATABASE_USER=root {posargs}