Developer Guide

This developer guide aims to get you started with developing LNT. At the moment, a lot of detailed info is missing, but hopefully this will get you started.


See Quickstart Guide for setting up an installation. Use the “develop” option when running ~/lnt/

Running LNT’s Regression Tests

LNT has a growing body of regression tests that makes it easier to improve LNT without accidentally breaking existing functionality. Just like when developing most other LLVM sub-projects, you should consider adding regression tests for every feature you add or every bug you fix. The regression tests must pass at all times, therefore you should run the regression tests as part of your development work-flow, just like you do when developing on other LLVM sub-projects.

The LNT regression tests make use of lit and other tools like FileCheck. At the moment, probably the easiest way to get them installed is to compile LLVM and use the binaries that are generated there. Assuming you’ve build LLVM into $LLVMBUILD, and installed lnt in $LNTINSTALL you can run the regression tests using the following command:

PATH=$LLVMBUILD/bin:$LNTINSTALL/bin:$PATH llvm-lit -sv ./tests

If you don’t like temporary files being created in your LNT source directory, you can run the tests in a different directory too:

mkdir ../run_lnt_tests
cd ../run_lnt_tests
PATH=$LLVMBUILD/bin:$LNTINSTALL/bin:$PATH llvm-lit -sv ../lnt/tests

For simple changes, adding a regression test and making sure all regression tests pass, is often a good enough testing approach. For some changes, the existing regression tests aren’t good enough at the moment, and manual testing will be needed.

Optional Tests

Some tests require additional tools to be installed and are not enabled by default. You can enable them by passing additional flags to lit:

Enable postgres database support testing. This requires at least postgres version 9.2 and the initdb and postgres binaries in your path. Note that you do not need to setup an actual server, the tests will create temporary instances on demand.
Enable mysql database support testing. This requires MySQL-python to be installed and expects the mysqld and mysqladmin binaries in your path. Note that you do not need to setup an actual server, the tests will create temporary instances on demand.
Check generated html pages for errors using tidy-html5. This requires pytidylib and tidy-html5 to be installed.
Enable reporting, assuming the coverage module has been installed and in the virtualenv has been modified appropriately.


PATH=$LLVMBUILD/bin:$LNTINSTALL/bin:$PATH llvm-lit -sv -Dpostgres=1 -Dmysql=1 -Dtidylib=1 ../lnt/tests