Python Koans

This is an adapted and simplified version of the Python Koans repo you can find at:

https://github.com/gregmalcolm/python_koans

Python Koans is an interactive tutorial for learning the Python programming language by making tests pass.

Most tests are fixed by filling the missing parts of assert functions. Eg:

self.assertEqual(__, 1+2)

which can be fixed by replacing the __ part with the appropriate code:

self.assertEqual(3, 1+2)

Occasionally you will encounter some failing tests that are already filled out. In these cases you will need to finish implementing some code to progress. For example, there is an exercise for writing some code that will tell you if a triangle is equilateral, isosceles or scalene.

As well as being a great way to learn some Python, it is also a good way to get a taste of Test Driven Development (TDD).

Getting Started

To test your koans just run:

python3 contemplate_koans.py

or run the script provided:

./run.sh

The first run you will see apparently a test failed:

AssertionError: False is not True

It also tells you exactly where the problem is, it's an assert on line 12 of .\koans\about_asserts.py. This one is easy, just change False to True to make the test pass.

Sooner or later you will likely encounter tests where you are not sure what the expected value should be. For example:

class Dog:
    pass

def test_objects_are_objects(self):
    fido = self.Dog()
    self.assertEqual(__, isinstance(fido, object))

This is where the Python Command Line can come in handy. In this case I can fire up the command line, recreate the scenario and run queries:

Getting the Most From the Koans

Quoting the Ruby Koans instructions:

"In test-driven development the mantra has always been, red, green,
refactor. Write a failing test and run it (red), make the test pass
(green), then refactor it (that is look at the code and see if you
can make it any better). In this case you will need to run the koan
and see it fail (red), make the test pass (green), then take a
moment and reflect upon the test to see what it is teaching you
and improve the code to better communicate its intent (refactor)."