Learn what a test is and how to run the first one of your own with the pytest library! You will get used to the pytest testing framework and the command-line interface. You will also learn how to process specific contexts, like "failed tests" and "skipping the test" with pytest markers.

Introduction to Testing in Python

The first test suite

pytest.raises

Invoking pytest from CLI

Run the test!

Run with the keyword

Applying test markers

Markers use cases

Failed tests with xfail

Conditional skipping

Creating Tests with pytest

Learn what a fixture is and how to simplify your code by using it in tests. You will get familiar with the fixture @pytest.fixture decorator and the fixture tools. You will analyze your code to see the "fixture part" in it. Finally, learn how to use teardowns to prevent software failures.

Introduction to fixtures

Getting familiar with fixtures

Data preparation

Run with a fixture

Chain Fixtures Requests

Chain this out

List with a custom length

Fixtures autouse

autouse statements

Auto add numbers

Fixtures Teardowns

Data with teardown

Read data with teardown

Pytest Fixtures

Learn what the basic testing types are and their features. Learn about test cases and how they help to implement tests. You will get more skilled with creating test functions and running pytest from CLI in IDE exercises. Finally, you will be able to differentiate the different testing types and create tests for each of them.

Unit testing with pytest

Unit testing terms

Cover more test cases

Factorial of number

Run factorial

Feature testing with pytest

Feature or unit testing

Aggregate with sum

Integration testing with pytest

Integration test or not

Read the file

Performance testing with pytest

What is performance testing?

Finding an element

Speed of loops

Basic Testing Types

In this final chapter, you will meet the unittest framework. First, you will learn basic assertion methods, then its CLI interface, and how to use fixtures. Finally, you will put everything together in the practical examples of data pipelines.

Kennismaken met Unittest

Faculteit met unittest

Priem of niet

CLI-interface

import unittest

def func_factorial(number):
    if number < 0:
        raise ValueError('Factorial is not defined for negative values')
    factorial = 1
    while number > 1:
        factorial = factorial * number
        number = number - 1
    return factorial

class TestFactorial(unittest.TestCase):
    def test_positives(self):
        self.assertEqual(func_factorial(5), 120)

    def test_zero(self):
        self.assertEqual(func_factorial(0), 1)

    def test_negatives(self):
        with self.assertRaises(ValueError):
            func_factorial(-1)


Voer factorial uit met unittest

import unittest

def err_func_factorial(number):
    if number < 0:
        raise ValueError('Factorial is not defined for negative values')
    factorial = 1
    while number > 2:
        factorial = factorial * number
        number = number - 1
    return factorial

class TestFactorial(unittest.TestCase):
    def test_err_func_1(self):
        self.assertEqual(err_func_factorial(3), 6)
    def test_err_func_2(self):
        self.assertEqual(err_func_factorial(4), 24)


import unittest

def err_func_factorial(number):
    if number < 0:
        raise ValueError('Factorial is not defined for negative values')
    factorial = 1
    while number > 1:
        factorial = factorial * number
        number = number - 1
    return factorial

class TestFactorial(unittest.TestCase):
    def test_err_func_1(self):
        self.assertEqual(err_func_factorial(3), 6)
    def test_err_func_2(self):
        self.assertEqual(err_func_factorial(4), 24)


Foutieve faculteit

- Run this command to run the testing script with the verbose flag:
  python3 -m unittest -v err_factorial_unittest.py
  
- Run this command to run the testing script with the fail fast flag:
  python3 -m unittest -f err_factorial_unittest.py
  
- Run this command to run the testing script with the keyword flag:
  python3 -m unittest -k "err_func_1" err_factorial_unittest.py


Unittest-opties

Fixtures in unittest

import unittest

class TestWord(unittest.TestCase):
    # Fixture setup method
    def setUp(self):
        # Initialize the word banana here
        self.word = ____

    # Test method
    def test_the_word(self):
        # Add the tests here
        ____
        ____
        ____
    
    # Fixture teardown method
    def tearDown(self):
        # Delete the word variable here
        ____


import unittest

class TestWord(unittest.TestCase):
    # Fixture setup method
    def setUp(self):
        # Initialize the word banana here
        self.word = 'banana'

    # Test method
    def test_the_word(self):
        # Add the tests here
        self.assertIn('b', self.word)
        self.assertNotIn('B', self.word)
        self.assertNotIn('y', self.word)
    
    # Fixture teardown method
    def tearDown(self):
        # Delete the word variable here
        del self.word


Test de stringvariabele

import unittest

def check_palindrome(string):
    reversed_string = string[::-1]
    return string == reversed_string

def create_data():
    return ['level', 'step', 'peep', 'toot']

class TestPalindrome(unittest.TestCase):
    def setUp(self):
        # Initialize data here
        ____
    
    def test_func(self):
        expected_result = [True, False, True, True]
        data_checked = list(map(check_palindrome, self.data))
        # Verify the checked data here
        ____

    def tearDown(self):
        # Clear the data here
        ____


import unittest

def check_palindrome(string):
    reversed_string = string[::-1]
    return string == reversed_string

def create_data():
    return ['level', 'step', 'peep', 'toot']

class TestPalindrome(unittest.TestCase):
    def setUp(self):
        # Initialize data here
        self.data = create_data()
    
    def test_func(self):
        expected_result = [True, False, True, True]
        data_checked = list(map(check_palindrome, self.data))
        # Verify the checked data here
        self.assertEqual(data_checked, expected_result)

    def tearDown(self):
        # Clear the data here
        self.data.clear()


Palindroomcontrole

Praktische voorbeelden

import pytest
import pandas as pd

DF_PATH = "/usr/local/share/salaries.csv"
@pytest.fixture
def read_df():
    return pd.read_csv(DF_PATH)

def get_grouped(df):
    return df.groupby('work_year').agg({'salary': 'describe'})['salary']

def test_read_df(read_df):
    # Check the type of the dataframe
    ____
    # Check that read_df contains rows
    ____

def test_grouped(read_df):
    df = read_df
    salary_by_year = get_grouped(df)
    # Check the nulls here
    ____


import pytest
import pandas as pd

DF_PATH = "/usr/local/share/salaries.csv"
@pytest.fixture
def read_df():
    return pd.read_csv(DF_PATH)

def get_grouped(df):
    return df.groupby('work_year').agg({'salary': 'describe'})['salary']

def test_read_df(read_df):
    # Check the type of the dataframe
    assert isinstance(read_df, pd.DataFrame)
    # Check that df contains rows
    assert read_df.shape[0] > 0

def test_grouped(read_df):
    df = read_df
    salary_by_year = get_grouped(df)
    # Check the nulls here
    assert salary_by_year.isna().sum().sum() == 0


Integratie- en unittests

import pytest
import pandas as pd

DF_PATH = "/usr/local/share/salaries.csv"
@pytest.fixture
def read_df():
    return pd.read_csv(DF_PATH)

def get_grouped(df):
    return df.groupby('work_year').agg({'salary': 'describe'})['salary']

def test_feature_2022(read_df):
    salary_by_year = get_grouped(read_df)
    salary_2022 = salary_by_year.loc[2022, '50%']
    # Check the median type here
    ____
    # Check the median is greater than zero
    ____

# Use benchmark here
def test_reading_speed(____):
    ____


import pytest
import pandas as pd

DF_PATH = "/usr/local/share/salaries.csv"
@pytest.fixture
def read_df():
    return pd.read_csv(DF_PATH)

def get_grouped(df):
    return df.groupby('work_year').agg({'salary': 'describe'})['salary']

def test_feature_2022(read_df):
    salary_by_year = get_grouped(read_df)
    salary_2022 = salary_by_year.loc[2022, '50%']
    # Check the median type here
    assert isinstance(salary_2022, float)
    # Check the median is greater than zero
    assert 0 < salary_2022

# Use benchmark here
def test_reading_speed(benchmark):
    benchmark(pd.read_csv, DF_PATH)


Feature- en prestatietests

import unittest
import pandas as pd
DF_PATH = 'https://assets.datacamp.com/production/repositories/6253/datasets/f015ac99df614ada3ef5e011c168054ca369d23b/energy_truncated.csv'

def get_data():
    return pd.read_csv(DF_PATH)

def min_country(df):
    return df['VALUE'].idxmin()

class TestDF(unittest.TestCase):
    def setUp(self):
        self.df = get_data()
        self.df.drop('previousYearToDate', axis=1, inplace=True)
        self.df = self.df.groupby('COUNTRY')\
            .agg({'VALUE': 'sum'})

    def test_NAs(self):
        # Check the number of nulls
        ____

    def test_argmax(self):
        # Check that min_country returns a string
        ____

    def tearDown(self):
        self.df.drop(self.df.index, inplace=True)


import unittest
import pandas as pd
DF_PATH = 'https://assets.datacamp.com/production/repositories/6253/datasets/f015ac99df614ada3ef5e011c168054ca369d23b/energy_truncated.csv'

def get_data():
    return pd.read_csv(DF_PATH)

def min_country(df):
    return df['VALUE'].idxmin()

class TestDF(unittest.TestCase):
    def setUp(self):
        self.df = get_data()
        self.df.drop('previousYearToDate', axis=1, inplace=True)
        self.df = self.df.groupby('COUNTRY')\
            .agg({'VALUE': 'sum'})

    def test_NAs(self):
        # Check the number of nulls
        self.assertEqual(self.df.isna().sum().sum(), 0)

    def test_argmax(self):
        # Check that min_country returns a string
        self.assertIsInstance(min_country(self.df), str)

    def tearDown(self):
        self.df.drop(self.df.index, inplace=True)


Energie-pijplijn

Gefeliciteerd!

Writing tests with unittest

DS_salaries

Energy

Games

Veel mensen schrijven code. Sommigen krijgen het werkend en winstgevend. Maar zelfs de slimste programmeurs maken weleens een fout die miljoenen kan kosten. Hoe verklein je de kans op zo’n fiasco? Hoe zorg je dat je een programma maakt dat precies doet wat jij wilt? Het eenvoudige antwoord is: schrijf tests!

Tijdens deze reis leer je de basis van tests schrijven in Python. Je maakt kennis met vier typen softwaretestmethoden. Je schrijft je eigen tests om te controleren of een programma of datapijplijn werkt zoals verwacht voordat het naar productie gaat. Of het nu gaat om een onverwachte null, een typefout in je gegevensset of verwisselde tekens in een formule: met tests kun je die gevallen vinden en voorkomen.

Na afloop van de cursus ken je de verschillende testmethoden en kun je de meest geschikte kiezen voor een specifieke context. Je kunt deze tests ook ontwerpen en in Python implementeren met de libraries pytest en unittest.

<h2>Waarom testen?</h2>Veel mensen schrijven code. Sommigen van hen maken het succesvol en winstgevend. Maar soms maken zelfs de slimste programmeurs fouten die miljoenen dollars kunnen kosten. Hoe kun je de kans op zo'n ramp verkleinen? Hoe zorg je ervoor dat je een programma maakt dat precies doet wat je wilt? Het simpele antwoord is: schrijf tests!<br><br><h2>Python-testen: de basis</h2>Tijdens deze reis leer je de basis van het maken van tests in Python. Je zult vier soorten methoden voor het testen van software tegenkomen. Je gaat je eigen tests maken om te checken of het programma of een datapijplijn werkt zoals het hoort voordat het in productie gaat. Of het nu gaat om een onverwachte nul, een typefout in je dataset of verwisselde tekens in de vergelijking. Je kunt die gevallen opsporen met de tests, en dat zul je ook doen.<br><br><h2>Testen met pytest en unittest</h2>Na afloop van de cursus weet je welke soorten testmethoden er zijn en kun je de meest geschikte kiezen voor een bepaalde situatie. Je kunt die tests ook ontwerpen en in Python uitvoeren met behulp van de bibliotheken `pytest` en `unittest`.

Writing Functions in Python

Software Engineering Principles in Python

Beheers Python-test: Leer methoden, maak controles en zorg voor foutloze code met pytest en unittest.

Foutieve faculteit

Introductie tot testen in Python

Praktische interactieve oefening