Breaking up into Smaller Tests

Exercise 3 - propose unit tests

In groups come up with some possible unit tests for any of the code files in the problem.

Some example solutions (there are many more)

'etha'

• A known graph is initialised with a given distance matrix
• Check that the output of etha is equal to the value of 1/delta where delta is calculated independently

'average'

• A known graph is initialised with a given distance matrix
• Check that the average values calculated by the function is equal to a pre-calculated value
• Check what happens if a graph is created with a mix of integer and float

'init'

• check that a graph is created correctly for a given input
• check that the functions operate correctly?

A unit test for 'average'

Create 'test_antgraph.py':

from antgraph import AntGraph

Python nose library includes tests for equality, inequality, boolean values, thrown exceptions etc.

from nose.tools import assert_equal
    import numpy as np

def test_ones_distance_etha():
	distances = [[1 for col in range(3)] for row in range(3)]
            graph = AntGraph(3, distances)
            assert_equals(graph.etha(0,1), 1)

    def test_general_distance_etha():
            distances = [[0, 5, 4], [5, 0, 2],[4, 2, 0]]
            graph = AntGraph(3, distances)
	np.testing.assert_allclose(0.2, graph.etha(0,1), rtol=0, atol=0.01)

Running tests:

nosetests automatically finds, runs and reports on tests.

nosetests test_antgraph.py

. denotes successful test function calls.

Uses 'reflection' to find out the test functions - test_ function, module and file prefixes.

Note - these are very simple tests for something that could get quite complicated, it is good to start with some simple cases and build up.

Exercise - implement unit tests for the Travelling Salesman Problem Code

Choose a part of the travelling salesman problem - write some unit tests.

Start by writing out on paper what you are going to do.

Sanity Check it with someone.

Try writing the tests

- don't worry if things go wrong 
- stay calm, try to work through it, ask someone (or more likely tell someone what is going on and you'll figure it out yourself)