# Detailed Notes on Drake’s Unit Tests¶

## Introduction¶

Unit tests are essential for software maintainability. They demonstrate the correctness of existing code and prevent future changes from breaking the past functionality (i.e., regressions). They are the only way for developers to inform Drake’s Continuous Integration (CI) service how the software is supposed to behave.

## Unit Testing Frameworks¶

### C++ Code¶

Please use the Google Test Framework. It is already available as a required external in Drake’s super-build level.

### MATLAB Code¶

Please write an example and add it as a test in the directory’s CMakeLists.txt using drake_add_matlab_test(). ctest will consider the test failed if it times out or calls error.

## Enabling Long Running Unit Tests¶

Drake disables a number of long-running unit tests by default. To reduce continuous integration turnaround time, these tests run on the build servers post-submit, but not pre-submit. To enable these tests locally, execute:

cd drake-distro/build/drake
cmake -DLONG_RUNNING_TESTS=ON .


The last command above saves your new build option in [drake build artifacts directory]/CMakeCache.txt.

Before the long-running unit tests can be executed, you need to re-build Drake. make users should run:

cd drake-distro/build/drake
make clean
make


ninja users should run:

cd drake-distro/build/drake
ninja clean
ninja


Note that even after enabling long-running unit tests, certain tests may still be disabled due to required dependencies not being available. The following Github issue is tracking the documentation of unit tests dependencies: https://github.com/RobotLocomotion/drake/issues/2733.

## Running Every Unit Test¶

To run every enabled unit test, execute:

cd drake-distro/build/drake
ctest -VV


## Finding a Specific Unit Test¶

To find a specific unit test you can print a list of all enabled unit tests by executing the following commands:

cd drake-distro/build/drake
ctest -N


If you have a clue about a particular unit test’s name, you can pipe the output of the ctest -N command to grep. One way to learn the name of a unit test is to look at the CMakeLists.txt that adds the unit test to the build system.

## Running a Specific Test¶

Once you know the unit tests’ name, you can run it by executing:

cd drake-distro/build/drake
ctest -VV -C [build mode] -R [test name]


where: [build mode] is the build mode, e.g., Debug, RelWithDebInfo, or Release, and [test name] is the name of the test exactly as printed by ctest -N including, if any, the entire path to the test as printed on the screen.

## Example: Find And Run A Unit Test Named cascade_system¶

Find test:

cd drake-distro/build/drake
ctest -N | grep -i cascade


Run the test:

ctest -VV -C RelWithDebInfo -R cascade_system_test


## Enabling Assertions¶

To enable Drake’s assertions without switching to Debug mode, define DRAKE_ENABLE_ASSERTS for the C++ pre-processor when you configure the build, for example:

cd drake-distro/build
cmake .. -G Ninja -DCMAKE_CXX_FLAGS:STRING=-DDRAKE_ENABLE_ASSERTS
ninja


We recommend turning on assertions in all of your builds during development.