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-rw-r--r-- | doc/en/writing_plugins.rst | 50 |
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diff --git a/doc/en/writing_plugins.rst b/doc/en/writing_plugins.rst index 5f429c219..8660746bd 100644 --- a/doc/en/writing_plugins.rst +++ b/doc/en/writing_plugins.rst @@ -677,6 +677,56 @@ Example: print(config.hook) +.. _`addoptionhooks`: + + +Using hooks in pytest_addoption +------------------------------- + +Occasionally, it is necessary to change the way in which command line options +are defined by one plugin based on hooks in another plugin. For example, +a plugin may expose a command line option for which another plugin needs +to define the default value. The pluginmanager can be used to install and +use hooks to accomplish this. The plugin would define and add the hooks +and use pytest_addoption as follows: + +.. code-block:: python + + # contents of hooks.py + + # Use firstresult=True because we only want one plugin to define this + # default value + @hookspec(firstresult=True) + def pytest_config_file_default_value(): + """ Return the default value for the config file command line option. """ + + + # contents of myplugin.py + + + def pytest_addhooks(pluginmanager): + """ This example assumes the hooks are grouped in the 'hooks' module. """ + from . import hook + + pluginmanager.add_hookspecs(hook) + + + def pytest_addoption(parser, pluginmanager): + default_value = pluginmanager.hook.pytest_config_file_default_value() + parser.addoption( + "--config-file", + help="Config file to use, defaults to %(default)s", + default=default_value, + ) + +The conftest.py that is using myplugin would simply define the hook as follows: + +.. code-block:: python + + def pytest_config_file_default_value(): + return "config.yaml" + + Optionally using hooks from 3rd party plugins --------------------------------------------- |