The tests in this directory test Gamera using the
pytest framework.

The pytest framework must be installed from 

    https://pytest.org/

This package is not required for the proper functioning
of Gamera, only to run the tests. You can run all tests
with

    pytest --tb=no

Alternatively, you can run an individual unit test, say 
test_graph.py, with

    pytest --tb=no test_graph.py

In case of failures you can obtain more information
by omitting the option "--tb=no".
