conan-center-index

Test Packages

This is the main way that ConanCenter is able to validate the contents of a package are valid. It is required to provide a test_package/ sub-directory with every recipe. These are expected to work regardless of the options or settings used as this is what consumer will encounter when doing a conan create themselves. It’s possible to have ConanCenter run conan test on more then one test folder by using the test_ prefix.

Contents

* [Files and Structure](#files-and-structure)
* [CMake targets](#cmake-targets)
* [Testing more generators with `test_<something>`](#testing-more-generators-with-test_something)
* [Testing CMake variables from FindModules](#testing-cmake-variables-from-findmodules)
* [How it works](#how-it-works)
* [Minimalist Source Code](#minimalist-source-code)<!-- endToc -->

Files and Structure

See the recipe files and structures for a visual.

All ConanCenterIndex recipe should have a two test_folders One for the current CMake generator in test_package/.

Please refer to the Package Templates for the current practices about which files and what their content should be.

CMake targets

When using CMake to test a package, the information should be consumed using the CMakeDeps generator.

This typically will look like a CMakeLists.txt which contain lines similar to

find_package(fmt REQUIRED CONFIG)
# ...
target_link_libraries(test_ranges PRIVATE fmt::fmt)

Refer to the package template for more examples.

In ConanCenterIndex, we try to accurately represent the names of the targets and the information provided by CMake’s modules and config files that some libraries provide. If CMake or the library itself don’t enforce any target name, the default ones provided by Conan should be recommended. The minimal project in the test_package folder should serve as an example of the best way to consume the package, and targets are preferred over raw variables.

This rule applies for the global target and for components ones. The following snippet should serve as example:

We encourage contributors to check that not only the global target works properly, but also the ones for the components. It can be done creating and linking different libraries and/or executables.

Testing more generators with test_<something>

The CI will explore all the folders and run the tests for the ones matching test_*/conanfile.py pattern. You can find the output of all of them together in the testing logs.

Sometimes it is useful to test the package using different build systems (CMake, Autotools,…). Instead of adding complex logic to one test_package/conanfile.py file, it is better to add another test_<something>/conanfile.py file with a minimal example for that build system. That way the examples will be short and easy to understand and maintain. In some other situations it could be useful to test different Conan generators (e.g. CMakeDeps) using different folders and conanfile.py files.

When using more than one test_<something> folder, create a different project for each of them to keep the content of the conanfile.py and the project files as simple as possible, without the need of extra logic to handle different scenarios.

.
+-- recipes
|   +-- library_name/
|       +-- config.yml
|       +-- all/
|           +-- ...
|           +-- test_package/
|               +-- ...
|           +-- test_cmakedeps/
|               +-- conanfile.py
|               +-- CMakeLists.txt
|               +-- test_package.cpp

Testing CMake variables from FindModules

Recipes which provide Find Modules are strongly encouraged to module the file name, targets and or variables.

We will provide better docs in the near future, for now here are a few references:

• Convo: https://github.com/conan-io/conan-center-index/pull/13511
• early example: https://github.com/conan-io/conan-center-index/tree/master/recipes/libxml2/all/test_cmake_module_package
• Best reference: https://github.com/conan-io/conan-center-index/blob/master/recipes/expat/all/test_package_module/CMakeLists.txt#L9

How it works

The build service will explore all the folders and run the tests for the ones matching test_*/conanfile.py pattern. You can find the output of all of them together in the testing logs. Only the end of the logs are posted even if an earlier “test folder” may have failed.

Note: If, for any reason, it is useful to write a test that should only be checked using Conan v1, you can do so by using the pattern test_v1_*/conanfile.py for the folder. Please, have a look to linter notes to know how to prevent the linter from checking these files.

Remember that the test_<package> recipes should test the package configuration that has just been generated for the host context, otherwise it will fail in cross-building scenarios; before running executables, recipes should check conan.tools.build.can_run

Minimalist Source Code

The contents of test_package.c or test_package.cpp should be as minimal as possible, including a few headers at most with simple instantiation of objects to ensure linkage and dependencies are correct. Any build system can be used to test the package, but CMake or Meson are usually preferred.

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