Testing¶

First meeting¶

After this meeting students should:

Understand how assertion statements work
Understand how to write unit tests using assert statements
Understand how to write tests for documentation

Testing software¶

Discuss how we will write automated tests for the tsp library we wrote in the first section.

Writing the unit tests¶

Write the following in a test_tsp.py file:

import numpy as np
import matplotlib.pyplot as plt

import tsp

def test_get_tour_with_no_seed():
    number_of_stops = 4
    tour = tsp.get_tour(number_of_stops=number_of_stops)
    assert np.array_equal(tour, np.array([0, 1, 2, 3, 0]))

def test_get_tour_with_seed_0():
    number_of_stops = 4
    seed = 0
    tour = tsp.get_tour(number_of_stops=number_of_stops, seed=seed)
    assert np.array_equal(tour, np.array([0, 3, 2, 1, 0])), f"Obtained output is {tour}"

def test_get_tour_with_seed_1():
    number_of_stops = 4
    seed = 1
    tour = tsp.get_tour(number_of_stops=number_of_stops, seed=seed)
    assert np.array_equal(tour, np.array([0, 1, 3, 2, 0])), f"Obtained output is {tour}"


def test_swap_cities():
    tour = [0, 1, 3, 2, 4, 0]
    steps = (4, 1)
    new_tour = tsp.swap_cities(tour=tour, steps=steps)
    assert new_tour == [0, 4, 2, 3, 1, 0], f"Obtained output is {new_tour}"


def test_get_cost():
    distance_matrix = np.array(((0, 5, 2, 9), (5, 0, 3, 1), (2, 3, 0, 7), (9, 1, 7, 0)))
    tour = [0, 1, 2, 3, 0]
    cost = tsp.get_cost(tour=tour, distance_matrix=distance_matrix)
    assert cost == 24


def test_run_2_opt_algorithm_with_seed_0():
    distance_matrix = np.array(((0, 5, 2, 9), (5, 0, 3, 1), (2, 3, 0, 7), (9, 1, 7, 0)))
    number_of_stops = 4
    seed = 0
    iterations = 50
    tour = tsp.run_2_opt_algorithm(number_of_stops=number_of_stops,
            distance_matrix=distance_matrix, seed=seed, iterations=iterations)
    assert tour == [0, 2, 3, 1, 0], f"Obtained output is {tour}"

def test_run_2_opt_algorithm_with_seed_1():
    distance_matrix = np.array(((0, 5, 2, 9), (5, 0, 3, 1), (2, 3, 0, 7), (9, 1, 7, 0)))
    number_of_stops = 4
    seed = 1
    iterations = 50
    tour = tsp.run_2_opt_algorithm(number_of_stops=number_of_stops,
            distance_matrix=distance_matrix, seed=seed, iterations=iterations)
    assert tour == [0, 2, 1, 3, 0], f"Obtained output is {tour}"

def test_plot_tour():
    x = np.array([2, 3])
    y = np.array([2, 3])
    tour = np.array([0, 1, 0])
    plot = tsp.plot_tour(x=x, y=y, tour=tour)
    assert plot is None

test_get_tour_with_no_seed()
test_get_tour_with_seed_0()
test_get_tour_with_seed_1()
test_swap_cities()
test_get_cost()
test_run_2_opt_algorithm_with_seed_0()
test_run_2_opt_algorithm_with_seed_1()
test_plot_tour()

Run the above tests by running:

$ python test_tsp.py

Depending on time now discuss refactoring some of the code. For example:

Modify swap_cities to be called swap_steps as this name is more generic.
Possibly modify swap_cities/swap_steps so that it can handle numpy array outputs.

At each step modify the source code and then modify the tests.

Discuss importance of tests as a debugging tool.

Testing the documentation¶

Modify the documentation in the README.md file to use doctests:

# TSP

A library for solving instances of the travelling sales agent problem

## Tutorial

In this tutorial we will see how to use `tsp` to solve instances of the
[Travelling Salesman Problem](https://en.wikipedia.org/wiki/Travelling_salesman_problem)

Assuming we have the following distance matrix:

```python
>>> import numpy as np
>>> distance_matrix = np.array(((0, 5, 2, 9), (5, 0, 3, 1), (2, 3, 0, 7), (9, 1, 7, 0)))

```

We can obtain a tour using the following:

```python
>>> import tsp  # doctest: +SKIP
>>> tour = tsp.run_2_opt_algorithm(number_of_stops=4, distance_matrix=distance_matrix, iterations=1000, seed=0)  # doctest: +SKIP
>>> tour  # doctest: +SKIP
[0, 3, 1, 2, 0]

```

The `tsp` library includes further functionality which you can read in the
How To guides.

Note that the doctests are skipped when checked for this documentation.

Run the doc tests by typing:

$ python -m doctest README.md

Discussion around 3 pillars of software development¶

Specifically look at diagram in further information section: https://vknight.org/pfm/building-tools/07-testing/why/main.html#how-are-modularisation-documentation-and-testing-related

After class email¶

Send the following email after class:

Hi all,

A recording of today's class is available at <>.

In this class I went over automated testing.

In class we wrote unit and doctests for the Travelling Salesagent Problem.
You can find a different example (studying snakes and ladders) here:
https://vknight.org/pfm/building-tools/07-testing/tutorial/main.html

Please get in touch if I can assist with anything,
Vince