I have made the test and I didn't encounter the error you reported. Could you please check that the file you uploaded to the resource folder, i.e. SquarePathMetric.py, contains the definition of the python class SquarePathMetric?
It should start like this:
from math import sqrt
from math import exp
from math import acos
"""Class used to handle the metric of the square path benchmark."""
Class used to represent one side of the square.
It handles the performance of the robot for this segment.
# Map between pairs of quarters and the vertex in between.
# This is used to detect when the robot has reached the
# next segment.
QUARTERS2VERTEX = [
[None, 1, 0, 0],
[1, None, 2, 1],
[2, 2, None, 3],
[0, 3, 3, None]
initialized = False
Note that you should remove this definition from the benchmark_evaluation transfer function too.