Testing - unit tests

The Ceph GitHub repository has two types of tests: unit tests (also called make check tests) and integration tests. Strictly speaking, the make check tests are not “unit tests”, but rather tests that can be run easily on a single build machine after compiling Ceph from source, whereas integration tests require package installation and multi-machine clusters to run.

What does “make check” mean?

After compiling Ceph, the code can be run through a battery of tests. For historical reasons, this is often referred to as make check even though the actual command used to run the tests is now ctest. To be included in this group of tests, a test must:

  • bind ports that do not conflict with other tests

  • not require root access

  • not require more than one machine to run

  • complete within a few minutes

For the sake of simplicity, this class of tests is referred to as “make check tests” or “unit tests”. This is meant to distinguish these tests from the more complex “integration tests” that are run via the teuthology framework.

While it is possible to run ctest directly, it can be tricky to correctly set up your environment for it. Fortunately, there is a script that makes it easy to run the unit tests on your code. This script can be run from the top-level directory of the Ceph source tree by invoking:


You will need a minimum of 8GB of RAM and 32GB of free drive space for this command to complete successfully on x86_64 architectures; other architectures may have different requirements. Depending on your hardware, it can take from twenty minutes to three hours to complete.

How unit tests are declared

Unit tests are declared in the CMakeLists.txt file, which is found in the ./src directory. The add_ceph_test and add_ceph_unittest CMake functions are used to declare unit tests. add_ceph_test and add_ceph_unittest are themselves defined in ./cmake/modules/AddCephTest.cmake.

Some unit tests are scripts and other unit tests are binaries that are compiled during the build process.

  • add_ceph_test function - used to declare unit test scripts

  • add_ceph_unittest function - used for unit test binaries

Unit testing of CLI tools

Some of the CLI tools are tested using special files ending with the extension .t and stored under ./src/test/cli. These tests are run using a tool called cram via a shell script called ./src/test/run-cli-tests. cram tests that are not suitable for make check can also be run by teuthology using the cram task.

Tox-based testing of Python modules

Some of the Python modules in Ceph use tox to run their unit tests.

Most of these Python modules can be found in the directory ./src/pybind/.

Currently (December 2020) the following modules use tox:

  • Cephadm (./src/cephadm/tox.ini)

  • Ceph Manager Python API (./src/pybind/mgr)

    • ./src/pybind/mgr/tox.ini

    • ./src/pybind/mgr/dashboard/tox.ini

    • ./src/pybind/tox.ini

  • Dashboard (./src/pybind/mgr/dashboard)

  • Python common (./src/python-common/tox.ini)

  • CephFS (./src/tools/cephfs/tox.ini)

  • ceph-volume

    • ./src/ceph-volume/tox.ini

    • ./src/ceph-volume/plugin/zfs/tox.ini

    • ./src/ceph-volume/ceph_volume/tests/functional/batch/tox.ini

    • ./src/ceph-volume/ceph_volume/tests/functional/simple/tox.ini

    • ./src/ceph-volume/ceph_volume/tests/functional/lvm/tox.ini

Configuring Tox environments and tasks

Most tox configurations support multiple environments and tasks.

The list of environments and tasks that are supported is in the tox.ini file, under envlist. For example, here are the first three lines of ./src/cephadm/tox.ini:

envlist = py3, mypy

In this example, the Python 3 and mypy environments are specified.

The list of environments can be retrieved with the following command:

tox --list


tox -l

Running Tox

To run tox, just execute tox in the directory containing tox.ini. If you do not specify any environments (for example, -e $env1,$env2), then tox will run all environments. Jenkins will run tox by executing ./src/script/run_tox.sh.

Here are some examples from Ceph Dashboard that show how to specify different environments and run options:

## Run Python 2+3 tests+lint commands:
$ tox -e py27,py3,lint,check

## Run Python 3 tests+lint commands:
$ tox -e py3,lint,check

## To run it as Jenkins would:
$ ../../../script/run_tox.sh --tox-env py3,lint,check

Manager core unit tests

Currently only doctests inside mgr_util.py are run.

To add more files to be tested inside the core of the manager, open the tox.ini file and add the files to be tested at the end of the line that includes mgr_util.py.

Unit test caveats

  1. Unlike the various Ceph daemons and ceph-fuse, the unit tests are linked against the default memory allocator (glibc) unless they are explicitly linked against something else. This enables tools such as valgrind to be used in the tests.

  2. Google Test unit testing library hides the client output from the shell. In order to debug the client after setting the desired debug level (e.g ceph config set client debug_rbd 20), the debug log file can be found at build/out/client.admin.<pid>.log. This can also be handy when examining teuthology failed unit test jobs, the job’s debug level can be set at the relevant yaml file.