11. Development

This section only needs to be read by developers of the pywbem package. People that want to make a fix or develop some extension, and people that want to test the project are also considered developers for the purpose of this section.

11.1. Repository

The repository for pywbem is on GitHub:


11.2. Setting up the development environment

You may use any supported OS platform as the development environment for pywbem. On native Windows, you need to use a Windows command prompt in administrator mode.

  1. It is recommended that you set up a virtual Python environment. Have the virtual Python environment active for all remaining steps.

  2. Make sure the following commands are available:

  3. Clone the Git repo of this project and switch to its working directory:

    $ git clone git@github.com:pywbem/pywbem.git
    $ cd pywbem
  4. Install the prerequsites for pywbem development. This will install Python packages into the active Python environment, and OS-level packages:

    $ make develop
  5. This project uses Make to do things in the currently active Python environment. The command:

    $ make

    displays a list of valid Make targets and a short description of what each target does. See the next sections for details.

11.3. Building the documentation

The ReadTheDocs (RTD) site is used to publish the documentation for the pywbem package at https://pywbem.readthedocs.io/

This page is automatically updated whenever the Git repo for this package changes the branch from which this documentation is built.

In order to build the documentation locally from the Git work directory, execute:

$ make builddoc

The top-level document to open with a web browser will be build_doc/html/docs/index.html.

11.4. Testing

All of the following make commands run the tests in the currently active Python environment, and need to be invoked in the Git repo work directory.

By default, the tests use the pywbem and pywbem_mock modules from the respective directories in the Git repo work directory. Pywbem 0.14.5 introduced a way to test installed versions of the pywbem package. For details, see Testing installed versions of pywbem.

The tests directory has the following subdirectory structure:

 +-- unittest            Unit tests
 |    +-- utils               Utility functions used by unit tests
 |    +-- pywbem              Unit tests for the pywbem package
 |    +-- pywbem_mock         Unit tests for the pywbem_mock package
 |    +-- unittest_utils      Unit tests for tests/unittest/utils
 |    +-- functiontest        Unit tests for tests/functiontest
 |    +-- end2endtest_utils   Unit tests for tests/end2endtest/utils
 |    +-- servers             Unit tests for tests/servers
 +-- functiontest        Function tests
 +-- end2endtest         End2end tests
 |    +-- utils               Utility functions used by end2end tests
 +-- manualtest          Manual tests
 +-- server_definitions  WBEM server definition file used by some tests and module
 |                         for accessing it
 +-- profiles            Simple definitions of management profiles used by some tests
 +-- schema              The CIM schema MOF files used by some MOF tests
 +-- dtd                 The CIM DTD file used by some CIM-XML validation tests

There are multiple types of tests in pywbem:

  1. Unit tests and function tests

    These tests do not require any WBEM server to be available, and the tests validate their results automatically.

    The distinction between unit tests and function tests as used in pywbem is that function tests exercise the entire pywbem client component or entire pywbem scripts, while unit tests exercise single modules.

    They are run by executing:

    $ make test

    Test execution can be modified by a number of environment variables, as documented in the make help (execute make help).

    An alternative that does not depend on the makefile and thus can be executed from the source distribution archive, is:

    $ ./setup.py test

    Options for pytest can be passed using the --pytest-options option.

  2. End2end tests

    These tests are run against one or more WBEM servers, and the tests validate their results automatically.

    They are run by preparing a server definition file:


    from the provided example, and by executing:

    $ make end2endtest

    Again, test execution can be modified by a number of environment variables, as documented in the make help (execute make help).

    An alternative that does not depend on the makefile, is:

    $ ./setup.py end2endtest

    Options for pytest can be passed using the --pytest-options option.

  3. Manual tests

    There are several Python scripts and shell scripts that can be run manually. The results need to be validated manually.

    These scripts are in the directory:


    and are executed by simply invoking them from within the main directory of the repository, e.g.:


    Some of the scripts support a –help option that informs about their usage.

    The run_cim_operations.py script needs a particular MOF file loaded in the repository of the WBEM server that is used for the test. This can be done using the MOF compiler of pywbem:

    $ mof_compiler -s <target_url> tests/unittest/pywbem/test.mof

To run the unit and function tests in all supported Python environments, the Tox tool can be used. It creates the necessary virtual Python environments and executes make test (i.e. the unit and function tests) in each of them.

For running Tox, it does not matter which Python environment is currently active, as long as the Python tox package is installed in it:

$ tox                              # Run tests on all supported Python versions
$ tox -e py27                      # Run tests on Python 2.7

11.5. Testing from the source archives on Pypi or GitHub

The wheel distribution archives on Pypi (e.g. pywbem-1.0.0-py2.py3-none-any.whl) contain only the files needed to run pywbem, but not the files needed to test it.

The source distribution archives on Pypi and GitHub (e.g. pywbem-1.0.0.tar.gz) contain all files that are needed to run and to test pywbem.

This allows testing pywbem without having to check out the entire repository, and is convenient for testing e.g. when packaging pywbem into OS-level packages.

When installing these source distribution archives, the files needed for running pywbem are installed into the active Python environment, but not the test files.

The following commands download the source distribution archive on Pypi for a particular version of pywbem into the current directory and unpack it:

$ pip download --no-deps --no-binary :all: pywbem==1.0.0
$ tar -xf pywbem-1.0.0.tar.gz
$ cd pywbem-1.0.0
$ ls -1
-rw-r--r--   1 maiera  staff    468 Jun 29 22:31 INSTALL.md
-rw-r--r--   1 maiera  staff  26436 May 26 06:45 LICENSE.txt
-rw-r--r--   1 maiera  staff    367 Jul  3 07:54 MANIFEST.in
-rw-r--r--   1 maiera  staff   3451 Jul  3 07:55 PKG-INFO
-rw-r--r--   1 maiera  staff   7665 Jul  2 23:20 README.rst
-rw-r--r--   1 maiera  staff   1624 Jul  2 23:20 README_PYPI.rst
-rwxr-xr-x   1 maiera  staff   2881 Jun 29 22:31 build_moftab.py
-rwxr-xr-x   1 maiera  staff  13850 Jun 29 22:31 mof_compiler
-rw-r--r--   1 maiera  staff    105 May 26 06:45 mof_compiler.bat
drwxr-xr-x  29 maiera  staff    928 Jul  3 07:55 pywbem
drwxr-xr-x   8 maiera  staff    256 Jul  3 07:55 pywbem.egg-info
drwxr-xr-x  18 maiera  staff    576 Jul  3 07:55 pywbem_mock
-rw-r--r--   1 maiera  staff   1067 Jun 29 22:31 requirements.txt
-rw-r--r--   1 maiera  staff     38 Jul  3 07:55 setup.cfg
-rwxr-xr-x   1 maiera  staff   7555 Jul  3 07:24 setup.py
-rw-r--r--   1 maiera  staff   2337 Jul  2 23:20 test-requirements.txt
drwxr-xr-x  15 maiera  staff    480 Jul  3 07:55 tests

Pywbem, its dependent packages, and packages needed for testing pywbem can be installed with the package extra named “test”:

$ pip install .[test]

When testing pywbem installations in Linux distributions that include pywbem as an OS-level package, the corresponding OS-level packages would instead be installed for these dependent Python packages. The test-requirements.txt file shows which dependent Python packages are needed for testing pywbem.

Finally, the tests can be run using the setup.py script:

$ ./setup.py test
$ ./setup.py leaktest
$ ./setup.py end2endtest

These commands are listed in the help of the setup.py script:

$ ./setup.py --help-commands
. . .
Extra commands:
  . . .
  test              pywbem: Run unit and function tests using pytest
  leaktest          pywbem: Run leak tests using pytest
  end2endtest       pywbem: Run end2end tests using pytest
  . . .

The additional options supported by these commands are shown in their help:

$ ./setup.py test --help
. . .
Options for 'test' command:
  --pytest-options  additional options for pytest, as one argument
. . .

Note: The test command of setup.py is not the deprecated built-in command (see https://github.com/pypa/setuptools/issues/1684), but has been implemented in setup.py in such a way that it only runs the tests but does not install anything upfront. The leaktest and end2endtest commands have been implemented in the same way. Therefore, this approach can be used for testing pywbem installations from OS-level packages in Linux distributions that include pywbem.

11.6. Testing installed versions of pywbem

By default, the tests use the pywbem and pywbem_mock modules from the respective directories in the Git repo work directory.

Pywbem 0.14.5 introduced a way to test installed versions of the pywbem package. This is useful for example for testing a version of pywbem that has been packaged as an OS-level package. Typically, such a version would be installed into the system Python.

Some words of caution:

  • Testing an installed version of pywbem with test cases from a pywbem repo of a different version can result in failing test cases for several reasons:

    • If a new version of pywbem has added functionality, its test cases are also extended accordingly. Running such newer test cases against an older installed version of pywbem may fail simply because the installed version does not yet have the added functionality.

    • Fixes in pywbem or in the test cases may change behavior in a subtle way that causes test cases to fail.

    • Unit test cases are particularly vulnerable to version mismatches because they test at the module level, including module interfaces that are internal to pywbem and thus can legally change incompatibly between versions.

  • If the version of the installed pywbem is before 0.14.5, some test cases that compile MOF will be skipped to avoid permission denied errors when ply attempts to re-generate its parsing table files in the pywbem installation directory in case of ply version mismatches. Starting with pywbem 0.14.5, it has tolerance against ply version mismatches.

In order to not clutter up the system Python with Python packages needed for running the pywbem tests, the following steps use a virtual Python environment that uses the packages of the system Python. That way, the installed version of pywbem becomes available to the virtual Python environment from the system Python, while any additional packages that are needed but not yet available that way, will be installed into the virtual Python environment.

Follow these steps to run pywbem tests against a version of pywbem that is installed into the system Python:

  1. Verify that the following commands are available when the system Python is active:

    $ virtualenv --version   # Python virtualenv package
    $ pip --version
  2. Create and activate a virtual Python environment of the intended Python version, that is based on the system Python:

    $ virtualenv --system-site-packages --no-setuptools --no-pip --no-wheel .virtualenv/test
    $ source .virtualenv/test/bin/activate

    The pywbem project is set up so that Git ignores the .virtualenv directory, so use that directory name for ease of Git handling.

  3. Verify that in that virtual Python environment, pywbem comes from the intended installation:

    $ pip show pywbem
  4. Ensure a fresh start of the make process. This should be done whenever switching between the installed version of pywbem and the local directories:

    $ make clobber
  5. Run the pywbem tests with environment variable TEST_INSTALLED being set:

    $ TEST_INSTALLED=1 make test

    This will assume that the pywbem package and any prerequisite Python packages and OS-level packages are already installed.

    This will also move the current directory (i.e. the repo working directory) to the end of the module search path, so that the installed version of pywbem is used when importing it into the test scripts.

    Setting TEST_INSTALLED=DEBUG causes some debug messages to be printed that allow verifying from where the pywbem and pywbem_mock modules are loaded.

    This also works for the pywbem end2end tests:

    $ TEST_INSTALLED=1 make end2end

Note that tox does not support creating its virtual Python environments based on the system Python, so at this point, tox cannot be used for this approach.

11.7. Updating the DMTF MOF Test Schema

Pywbem uses DMTF CIM Schemas in its CI testing. The schema used is stored in the form received from the DMTF in the directory tests/schema and is expanded and compiled as part of the unit tests.

Since the DMTF regularly updates the schema, the pywbem project tries to stay up-to-date with the current schema. At the same time, earlier schemas can be used for testing also by changing the definitions for the dmtf schema to be tested.

The schema used for testing can be modified by modifying the test file:


11.8. Developing PyWBEM Ipython Documentation Notebooks

The pywbem developers are using ipython notebooks to demonstrate the use of pywbem. Today we generally have one notebook per operation or group of operations including definition of the operation, references back to the pywbem documentation, and one or more examples (hopefully examples that will actually execute against a wbem server)

These can easily be extended or supplemented using a local ipython or jupyter server by:

1. Install ipython or Jupyter software using pip or pip3. The notebook server may be installed as root or within a python virtual environment. For example:

$ sudo pip install ipython
$ sudo pip3 install ipython
$ sudo pip install jupyter

The notebook server may be installed as root or within a python virtual environment.

2. Start the local ipython/jupyter notebook server in the notebook directory (pywbem/docs/notebooks) referencing that directory in the command line call:

$ ipython notebook docs/notebooks
$ jupyter notebook docs/notebooks

This will start the local ipython/juypter notebook server and on the first page displayed in your web browser all existing pywbem ipython notebooks will be available for editing. New ones can be created using the commands on that ipython server web page.

New and changed notebooks must go through the same contribution process as other components of pywbem to be integrated into the github repository.

11.9. Contributing

Third party contributions to this project are welcome!

In order to contribute, create a Git pull request, considering this:

  • Test is required.

  • Each commit should only contain one “logical” change.

  • A “logical” change should be put into one commit, and not split over multiple commits.

  • Large new features should be split into stages.

  • The commit message should not only summarize what you have done, but explain why the change is useful.

  • The commit message must follow the format explained below.

What comprises a “logical” change is subject to sound judgement. Sometimes, it makes sense to produce a set of commits for a feature (even if not large). For example, a first commit may introduce a (presumably) compatible API change without exploitation of that feature. With only this commit applied, it should be demonstrable that everything is still working as before. The next commit may be the exploitation of the feature in other components.

For further discussion of good and bad practices regarding commits, see:

11.10. Core Development Team

Anyone can contribute to pywbem via pull requests as described in the previous section.

The pywbem project has a core development team that holds regular web conferences and that is using Slack for offline communication, on the Slack workspace: https://pywbem.slack.com.

The web conference and the Slack workspace are by invitation, and if you want to participate in the core team, please open an issue to let us know.