How to do a class or test function with pytest?

Question

Be a Python program, for example, the calculation of Fibonnaci:

def fibR(n):
 if n==1 or n==2:
  return 1
 return fib(n-1)+fib(n-2)
print (fibR(5))

How to do a test class/function using pytest, for example?

Answer 1

def fibR(n):
 if n==1 or n==2:
  return 1
 return fibR(n-1)+fibR(n-2)

In the same directory:test_fib.py:

import pytest
from fib import fibR

def test_fib_1_equals_1():
    assert fibR(1) == 1

def test_fib_2_equals_1():
    assert fibR(2) == 1

def test_fib_6_equals_8():
    assert fibR(6) == 8

Reply from @Tagc of the English version of stackoverflow.