# Tests¶

## Unit tests¶

Unit testing is done with pytest. Run the tests in the freegs directory with:

pytest


## Convergence test¶

The test-convergence.py script solves for the same plasma as the 01-freeboundary.py example, with four poloidal field coils and an X-point. The change in results as the resolution is doubled is plotted as a function of grid resolution. This is therefore not testing convergence to a known solution, but is a check that the code converges to value, and indication of its convergence rate. Results are shown below, using the von Hagenow free boundary, and 4th-order solver for the poloidal flux .

This indicates that in general convergence is between 2nd and 4th-order. The plasma volume is currently calculated by integrating over the poloidal cross-section, and could be improved by converting this to a surface integral.