Python Pytest example

1. Fifo dode to test: file is fifo.py

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"""
Fifo class
"""
class Fifo:
    def __init__(self):
        """ the fifo queue """
        self.qu = []


    def push(self, val):
        """ push onto stack """
        self.qu.append(val)


    def pop(self):
        """ Pops the last pushed on stack """
        if len(self.qu):
            val = self.qu.pop()
            return val
        else:
            return None


    def shift(self):
        """ removed the first from queue """
        if len(self.qu):
            val = self.qu[0]
            self.qu.remove(val)
            return val
        else:
            return None


    def unshift(self, val):
        """ add to front of queue """
        self.qu.insert(0, val)


    def count(self):
        return len(self.qu)

    def bump(nn):
        """ example class function, no self """
        return nn + 1

2. Pytest test functions: file = test_fifo.py

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"""
pip install pytest
"""

from fifo import Fifo

def test_stack():
    fifo = Fifo()
    assert fifo.count() == 0

    fifo.push(1)
    fifo.push(2)
    fifo.push(3)
    fifo.push(4)
    fifo.push(5)
    assert fifo.count() == 5

    val = fifo.pop()
    assert fifo.count() == 4
    assert val == 5


def test_fifo():
    fifo = Fifo()
    assert fifo.count() == 0

    fifo.push(1)
    fifo.push(2)
    fifo.push(3)
    fifo.push(4)
    fifo.push(5)
    assert fifo.count() == 5

    val = fifo.shift()
    assert fifo.count() == 4
    assert val == 1

    val = fifo.shift()
    assert fifo.count() == 3
    assert val == 2


def test_reverse_fifo():
    fifo = Fifo()
    assert fifo.count() == 0

    fifo.unshift(1)
    fifo.unshift(2)
    fifo.unshift(3)
    assert fifo.count() == 3

    val = fifo.pop()
    assert fifo.count() == 2
    assert val == 1

    val = fifo.pop()
    assert fifo.count() == 1
    assert val == 2

    val = fifo.pop()
    assert fifo.count() == 0
    assert val == 3

    val = fifo.pop()
    assert fifo.count() == 0
    assert val == None


def test_class_function():
    assert Fifo.bump(2) == 3

3. Run

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pytest test_fifo.py

=======================test session starts ===========================
platform darwin -- Python 3.6.1, pytest-3.2.1, py-1.4.34, pluggy-0.4.0
rootdir: /Users/phil/titan/python, inifile:
collected 4 items                                                                                   

test_fifo.py ....

=======================4 passed in 0.02 seconds ======================