LilyPond Contributor's Guide: 9.3 Compiling regression tests

## 9.3 Compiling regression tests

Developers may wish to see the output of the complete regression test suite for the current version of the source repository between releases. Current source code is available; see Working with source code. Then you will need to build the LilyPond binary; see Compiling LilyPond.

Uninstalling the previous LilyPond version is not necessary, nor is running `make install`, since the tests will automatically be compiled with the LilyPond binary you have just built in your source directory.

From this point, the regtests are compiled with:

>     make test

If you have a multi-core machine you may want to use the ‘`-j`’ option and CPU_COUT variable, as described in Saving time with `CPU_COUNT`. For a quad-core processor the complete command would be:

>     make -j5 CPU_COUNT=5 test

The regtest output will then be available in ‘`input/regression/out-test`’. ‘`input/regression/out-test/collated-examples.html`’ contains a listing of all the regression tests that were run, but none of the images are included. Individual images are also available in this directory.

The primary use of ‘`make test`’ is to verify that the regression tests all run without error. The regression test page that is part of the documentation is created only when the documentation is built, as described in Generating documentation. Note that building the documentation requires more installed components than building the source code, as described in Requirements for building documentation.

#### LilyPond — Contributor’s Guide