Getting started with pytest is quite easy. Let's write a test with a simple assert, then show the various ways to run this test.

Create a Player class

Let's create a simple Player class that we can use to write our first test. It will have three variables, two of type str and one of type int:

class Player:
    first_name: str
    last_name: str
    jersey: int

Write and run your first test

We can now get PyCharm to create a basic test for us from that code. Put your caret over it and then use Navigate to Test ⌘⇧T (macOS) / Ctrl+Shift+T (Windows/Linux):

Check that PyCharm is putting your test in your tests folder and change it if you need to then click OK:

PyCharm has now created a basic test for us which includes the line assert False, meaning that it should fail:

def test_player():
    assert False

You can run your tests in PyCharm in a variety of ways, let's start with the gutter icons:

As we expect the test fails. You can see this in the Run tool window:

Change the line to read assert True instead of assert False and then try running it again. This time we will run it with our keyboard shortcuts ⌃R (macOS) / Shift+F10 (Windows/Linux):

This Python pytest file has one function, test_player. In pytest, tests are discovered by default in filenames starting with test_ and functions/methods with that same prefix.

Test our constructor

Lacrosse teams have, of course, players. We are first implementing a Player class and writing tests as we implement features. This is known as "test-driven development" (TDD).

We aren't asserting anything about the instance. Simply: the import works, it's callable, and can be called. Let's change that to check our construction. Change your code to:

def test_construction():
    assert Player()

Remember that PyCharm can help you generate the import of Player as you type. You don't need to stop your flow, go to the top, and write the import. Instead, type Pla and use Ctrl+Space+Space to autocomplete and add the import line at the top, in the correctly-sorted location, combined with any existing import of the module.

Let's run everything in the file (currently one test) by right-clicking in the editor and choosing Run Python tests in test.... Our test passes again: