Feature testing with pytest

Introduction to Testing in Python

Alexander Levin

Data Scientist

What is a feature test

Feature

a software system functionality.
satisfies a particular user's requirement.

Features

are wider that units.
End-user can use features.

Feature testing

software testing method.
verify the behavior of a specific feature.

Examples:
- Data distribution check
- Report preparation

Units vs. features: personal computer

Units:

Each individual button
Pixels on the screen
LED diodes
Blocks on the disk

Features:

Keyboard
Screen
Illumination
File system

Why do we use feature tests

Feature testing helps:

To test things at the scope of the user interaction with a system.

The scope is wider than units:

One unit does not work - does not mean the feature is NOT OK.

Vice versa:

All units work as expected - does not mean the feature is OK.

Feature test example: setup

Setup and defining the feature code:

# Setup
import pandas as pd
import pytest

df = pd.read_csv('laptops.csv')

# Filter feature
def filter_data_by_manuf(df, manufacturer_name):
    filtered_df = df\
        [df["Manufacturer"] == manufacturer_name]
    return filtered_df

Feature test example: testing

Testing code:

# Feature test function
def test_unique():
    manuf_name = 'Apple'
    filtered = filter_data_by_manuf(df, manuf_name)
    assert filtered\
        ['Manufacturer'].nunique() == 1
    assert filtered\
        ['Manufacturer'].unique() == [manuf_name]

Summary

Feature testing - software testing method, allows to verify the behavior of a specific feature.

Features are wider that units:

If a button is a unit, then the keyboard is a feature.

Feature testing helps to ensure that users get exactly what they expect.

To create feature tests one has to create test cases.

The key to design feature tests - to understand what the features are in a specific system.

Let's practice!

Introduction to Testing in Python