What code is tested here?

PLUMED is an open-source, community-developed library that provides a wide range of different methods, which include:

These techniques can be used in combination with a large toolbox of collective variables that describe complex processes in physics, chemistry, material science, and biology.

PLUMED works together with some of the most popular MD engines, such as ACEMD, Amber, DL_POLY, GROMACS, LAMMPS, NAMD, OpenMM, ABIN, CP2K, i-PI, PINY-MD, and Quantum Espresso. In addition, PLUMED can be used to augment the capabilities of analysis tools such as VMD, HTMD, OpenPathSampling, and as a standalone utility to analyze pre-calculated MD trajectories.

Check it out here!