17.4.6 Emacs Packages

Emacs packages should preferably use the Emacs build system (see emacs-build-system), for uniformity and the benefits provided by its build phases, such as the auto-generation of the autoloads file and the byte compilation of the sources. Because there is no standardized way to run a test suite for Emacs packages, tests are disabled by default. When a test suite is available, it should be enabled by setting the #:tests? argument to #true. By default, the command to run the test is make check, but any command can be specified via the #:test-command argument. The #:test-command argument expects a list containing a command and its arguments, to be invoked during the check phase.

The Elisp dependencies of Emacs packages are typically provided as propagated-inputs when required at run time. As for other packages, build or test dependencies should be specified as native-inputs.

Emacs packages sometimes depend on resources directories that should be installed along the Elisp files. The #:include argument can be used for that purpose, by specifying a list of regexps to match. The best practice when using the #:include argument is to extend rather than override its default value (accessible via the %default-include variable). As an example, a yasnippet extension package typically include a snippets directory, which could be copied to the installation directory using:

#:include (cons "^snippets/" %default-include))

When encountering problems, it is wise to check for the presence of the Package-Requires extension header in the package main source file, and whether any dependencies and their versions listed therein are satisfied.