Unit Test Suite Overview

Table of Contents

• Module Test Pages
• Quick Start
• Aggregate CMake Targets
• MPI Test Registration
• Naming Conventions
  • C++ (CTest)
  • Python (pytest)
• Golden Values and Regression
• POSIX <tt>index()</tt> Ambiguity
• Rebuilding Before Testing

DNDSR uses doctest for C++ unit tests and pytest (with pytest-mpi) for Python tests. MPI-aware C++ tests are registered with CTest at multiple process counts to verify parallel correctness.

Module Test Pages

Module	Page	C++ tests	Python tests	Assertions
DNDS (core)	DNDS Core Unit Tests	7 executables	2 pytest files (~10 tests)	~400
Geom	Geom Module Unit Tests	5 executables	1 pytest file (1 test)	—
CFV	CFV Module Unit Tests	3 executables	2 pytest files (32 tests)	~340
Euler	Euler Module Unit Tests	4 executables	—	~310
Solver	Solver Module Unit Tests	4 executables	—	~65

Quick Start

# 1. Configure with tests enabled
cmake -B build -DDNDS_BUILD_TESTS=ON
 
# 2. Build all test executables
cmake --build build -t all_unit_tests -j8
 
# 3. Run the full C++ test suite
ctest --test-dir build --output-on-failure
 
# 4. Run Python tests (requires pybind11 shared libraries)
cmake --build build -t dnds_pybind11 geom_pybind11 cfv_pybind11 eulerP_pybind11 -j32
cmake --install build --component py
source venv/bin/activate
PYTHONPATH=python pytest test/ -v

Aggregate CMake Targets

Target	Contents
dnds_unit_tests	All DNDS core test executables
geom_unit_tests	All Geom test executables
cfv_unit_tests	All CFV test executables
euler_unit_tests	All Euler test executables
solver_unit_tests	All Solver test executables
all_unit_tests	All of the above

All test executables are EXCLUDE_FROM_ALL and must be built explicitly.

MPI Test Registration

MPI-aware tests are registered at multiple process counts. The CTest name encodes the count:

Module	Process counts	Timeout
DNDS	np = 1, 2, 4, 8	120-240 s
Geom	np = 1, 2, 4, 8	120-240 s
CFV	np = 1, 2, 4	120-180 s
Euler	np = 1, 2, 4	600 s

Serial tests have a single CTest entry with a 60-120 s timeout.

Naming Conventions

C++ (CTest)

<module>_<test_name>             # serial
<module>_<test_name>_np<N>       # MPI at N ranks

Examples: cfv_limiters, euler_evaluator_pipeline_np4, solver_ode.

Python (pytest)

test/<Module>/test_<name>.py::TestClass::test_method

Examples: test/CFV/test_fv_correctness.py::TestCellVolumes::test_wall_mesh_cell_volumes.

Golden Values and Regression

Many tests compare computed results against pre-captured golden values with a relative tolerance (typically 1e-6 to 1e-8). Golden values are deterministic because:

• Iterative VR uses Jacobi iteration (not SOR) to avoid partition-dependent update ordering.
• Euler pipeline tests use Jacobi update (not LU-SGS) for the same reason.
• Metis partitioning uses a fixed seed (metisSeed = 42).

When a golden value has not yet been captured, the sentinel 1e300 (or 0.0 in older tests) is stored. In this mode the test only prints the value and checks it is finite and non-negative — no regression assertion.

POSIX <tt>index()</tt> Ambiguity

Because doctest includes <cstring>, which transitively pulls in the POSIX index() function from <strings.h>, the bare name index is ambiguous when using namespace DNDS; is active. All C++ test files qualify the DNDS type aliases as DNDS::index, DNDS::real, and DNDS::rowsize in variable declarations.

Rebuilding Before Testing

Before running Python tests, always rebuild and reinstall the pybind11 shared libraries:

cmake --build build -t dnds_pybind11 geom_pybind11 cfv_pybind11 eulerP_pybind11 -j32
cmake --install build --component py

If C++ source changed since the last build, stale .so files produce misleading crashes (segfaults, aborts, wrong results) that look like code bugs.