Software Testing

Available on: http://pokoli.github.io/software-testing

Who am I?

Sergi Almacellas Abellana

(Python ♥) Programmer
Open source enthusiast
Automation Maniac

Bug Fixing Costs

TDD & BDD to the rescue!!

Test Driven Development

Write Test Case Ensure Test Fails Implement Functionality Ensure Test Pass Refractor Ensure Test Pass

TDD Example

def sum(a, b):
    return a + b

self.assertEqual(sum(1, 2), 3)

self.assertIsInstance(sum(1, 2), int)
self.assertNotIsInstance(sum(1.0, 2), int)

self.assertRaises(TypeError, sum('1', 2))
self.assertRaises(TypeError, sum())

But how to tests external services?

import requests
from datetime import date
url = 'http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml'

class CurrencyConverter(object):

    def get_ratios_xml(date):
        return resquests.get(url)

    def update_ratios():
        self.parse_data(self.get_ratios_xml(date.today()))

    def get_eur_to_usd(self, amount):
        if not self.ratios:
            self.update_ratios()
        return self.ratios['usd'] * amount

Mockups to the rescue!!!

from mock import patch

converter = CurrencyConverter()

def get_local_ratios_xml(d):
    self.assertEqual(d, date.today)
    return open('local.xml').read()


with patch.object(CurrencyConverter, 'get_ratios_xml', new=get_local_ratios_xml):
    self.assertEqual(converter.get_eur_to_usd(1), 1.12)

Behaviour Driven Development

TDD Extension (same filosofy) Describes User Interaction Who What effect Which bussiness effect

BDD Example

Story: Application login In order to use the aplicationAs a application userI want to Enter the application Scenario 1: Login with email and passwordGiven I have and valid emailAnd I obtained a password with signupWhen I enters the email and passwordThen I see my homepage.

Code Coverage

$ coverage report -m
Name                      Stmts   Miss  Cover   Missing
-------------------------------------------------------
my_program.py                20      4    80%   33-35, 39
my_other_module.py           56      6    89%   17-23
-------------------------------------------------------
TOTAL                        76     10

Mesure which % of code is tested
Allows to know which lines are not tested
As HTML report if desired

Please don't go mad with 100% coverage

When to run the tests?

Programmer always run tests?
Sure?
Always always always?
I don't belive you

Continuous Integration to the rescue!!!!

Continuous Integration

After commit hook Notifies author/manager when failure With multiple targets (e.g. Python 2 vs. Python 3) With multiple databases (e.g. PostgresSQL vs. MySQL)

But TDD+BDD+CI is enough?

NO!!Of course

Continous delivery to help you!

Continuous Delivery

Once CI has passed
To a staging server
Normally using commit hash
URL sent to testing team
Cheaper with containers (Docker)
Production when tagged

Summary: Full Process

Write Test Implement Functionality Run Test Commit and push CI Test on all platforms CD upgrades staging machine Repeat 1. for each functionality Testing team says OK Create tag on repo Commit and push CI Test on all platforms CD upgrades production machine

Summary: Results

Developers Quality Team Support Team Product Manager Users Managers

Summary: (Real) Results

More Quality control Find problems earlier Prevent regressions Code documentation Faster Development Faster Feedback Reduce change fear

Bonus: Upgrade dependency libs (personal experience)

Migrations ♥ Tests

My steps to migrate to new version:

Write tests (if none) Migrate tests (if required) Update dependencies Run tests Fix errors Repeat untill all green

Thank you!

The presentation code is avaiable on

http://github.com/pokoli/software-testing

Software Testing

pokoli

Software Testing

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