5.2.2. Regression test

The regression test executes a series of test cases which intend to fully describe OpenFAST and its module’s capabilities.

Jump to Running the regression test with CTest, Regression test example, or Windows with Visual Studio regression test for instructions on running the regression tests locally.

Each locally computed result is compared to a static set of baseline results. To account for system, hardware, and compiler differences, the regression test attempts to match the current machine and compiler type to the appropriate solution set from these combinations:

  • macOS with GNU compiler (default)
  • Red Hat Enterprise Linux with Intel compiler
  • Windows with Intel compiler

The compiler versions, specific math libraries, and hardware used to generate these baseline solutions are documented in the r-test repository documentation. Currently, the regression test supports only double precision solutions, so it is required to build OpenFAST in double precision for testing. All baseline solutions are generated with a double precision build.

The regression test system can be executed with CMake and CTest or manually with an included Python driver. Both systems provide similar functionality with respect to testing, but CTest integration provides access to multithreading, automation, and test reporting via CDash. Both modes of execution require some configuration as outlined below.

In both modes of execution a subdirectory is created in the build directory called reg_tests where all of the input files for the test cases are copied and all of the locally generated outputs are stored.

Ultimately, both CTest and the manual execution program call a series of Python scripts and libraries in reg_tests and reg_tests/lib. One such script is lib/pass_fail.py which reads the output files and computes a norm on each channel reported. If the maximum norm is greater than a preset tolerance, that particular test is reported as failed. The failure criteria is outlined in pseudocode below.

difference = abs(testData-baselineData)
for i in nChannels
   if channelRange < 1 {
      norm[i] = MaxNorm( difference[:,i] )
   } else {
      norm[i] = MaxNorm( difference[:,i] ) / channelRange

if max(norm) < tolerance:
  success Dependencies

  • Python 3+
  • Numpy
  • CMake and CTest (Optional)
  • matplotlib (Optional) Manual driver configuration

The regression test can be executed manually with the included driver openfast/reg_tests/manualRegressionTest.py. This program reads a case list file at openfast/reg_tests/r-test/glue-codes/openfast/CaseList.md. Cases can be removed or ignored with a #. This driver program includes multiple optional flags which can be obtained by executing with the help option: openfast/reg_tests/manualRegressionTest.py -h

For the NREL 5MW turbine test cases, an external ServoDyn controller must be compiled and included in the appropriate directory or all NREL 5MW cases will fail without starting. More information is available in the documentation for the r-test repository. CTest configuration

CTest is included with CMake and is mostly a set of preconfigured targets and commands. To use the CTest driver for the regression test, CMake must be run with one of two CMakeLists.txt‘s:

  • openfast/CMakeList.txt
  • openfast/reg_tests/CMakeLists.txt

CMake variables can be configured in the CMake GUI or through the command line interface with ccmake.

The regression test specific CMake variables are


IT IS IMPORTANT to verify that NREL 5MW turbine external controllers are compiled and placed in the correct location. More information is available in the documentation for the r-test repository, but be aware that these three DISCON controllers must exist


This can be accomplished manually with the CMake projects included with the DISCON source codes at openfast/reg_tests/r-test/glue-codes/openfast/5MW_Baseline/ServoDyn/ or during CMake configuration by setting the CMAKE_INSTALL_PREFIX CMake variable. If using this method, the install prefix variable should point to an existing and appropriate location for CMake to place the compiled binaries. This is important because the NREL 5MW turbine external controller CMake projects are preconfigured to install themselves in the appropriate location in the build directory. Then, it is important to execute make install rather than simply make. If CMAKE_INSTALL_PREFIX is not appropriately configured, the install step may fail or openfast binaries may be placed in some inappropriate default location.

After CMake configuration, the automated regression test can be executed by running either of the commands make test or ctest from the build directory. If the entire OpenFAST package is to be built, CMake will configure CTest to find the new binary at openfast/build/glue-codes/openfast/openfast. However, if the intention is to build only the test suite, the OpenFAST binary should be specified in the CMake configuration under the CTEST_OPENFAST_EXECUTABLE flag. There is also a corresponding CTEST_[MODULE]_NAME flag for each module included in the regression test. Running the regression test with CTest

When driven by CTest, the regression test can be executed by running various forms of the command ctest from the build directory. The basic commands are

  • ctest - Run the entire regression test
  • ctest -N - Disable actual execution of tests; this is helpful in formulating a particular ctest command
  • ctest -V - Run the entire regression test with verbose output
  • ctest -R [TestName] - Run a test by name where TestName is a regex to search
  • ctest -j [N] - Run all tests with N tests executing in parallel

Each regression test case contains a series of labels associating all of the modules used. The labeling can be seen in the test instantiation in reg_tests/CTestList.cmake or with the command

  • ctest --print-labels - Print all available test labels

Labels can be called directly with

  • ctest -L [Label]

These flags can be compounded making useful variations of ctest such as

  • ctest -V -L aerodyn14 - Runs all cases that use AeroDyn14 with verbose output
  • ctest -j 16 -L aerodyn14 - Runs all cases that use AeroDyn14 in 16 concurrent processes
  • ctest -V -R 5MW_DLL_Potential_WTurb - Runs the case with name “5MW_DLL_Potential_WTurb”
  • ctest -N -L beamdyn - Lists all tests with the “beamdyn” label
  • ctest -N -R bd --print-labels - Lists the labels included in all tests matching the regex “bd”

The automated regression test writes new files only into the build directory. Specifically, all locally generated solutions are located in the corresponding glue-code or module within openfast/build/reg_tests. The baseline solutions contained in openfast/reg_tests/r-test are strictly read not modified by the automated process. Regression test example

  • Build OpenFAST and the test suite
git clone --recursive https://github.com/openfast/openfast.git
# The default git branch is 'master'. If necessary, switch to your target branch:
# git checkout dev
mkdir build install && cd build
# Configure CMake with openfast/CMakeLists.txt
make install
  • Build only the test suite if an openfast binary already exists
git clone --recursive https://github.com/openfast/openfast.git
# The default git branch is 'master'. If necessary, switch to your target branch:
# git checkout dev
mkdir build install && cd build
# Configure CMake with openfast/reg_tests/CMakeLists.txt
cmake ../reg_tests
make install

Follow the link above for a detailed procedure. It is summarized below though excluding the procedure to build OpenFAST itself.

git clone --recursive https://github.com/openfast/openfast.git
cd openfast

## Build the ServoDyn external controller libraries
# Open the Visual Studio Solution (DISCON.sln) located in 'openfast\vs-build\DISCON'
# Choose Release and x64 for the Solutions Configuration and Solutions Platform
# Build Solution

## Execute the OpenFAST regression Tests
# Open a command prompt which is configured for Python (like Anaconda)
cd openfast\reg_tests
python manualRegressionTest.py ..\build\bin\openfast_x64.exe Windows Intel 1e-5