Adventures in Machine Learning

Python Unit Testing: Ensuring the Quality of Your Code

The Importance of Testing Phase in Software Development

As we all know, software development is a complex and multifaceted process. At each stage of the development cycle, developers need to ensure that the product meets the required standards, is free of bugs and errors, and is delivered on time.

One of the key aspects of software development is the Testing Phase. It is important to ensure that the software is tested thoroughly before its release to minimize errors and maximize its efficiency and quality.

The Testing Phase is an integral part of software development because it identifies errors and defects that may affect the software’s functionality or its user experience. Testing is essential because it helps identify problems early on and prevents them from getting bigger and more complicated.

Development firms want to minimize costs and ensure that the final product is delivered faster and with the highest quality possible. This is where testing comes in handy.

Types of Testing in Software Development

Testing is a process of evaluating a software product to identify its vulnerabilities and potential problems. There are different types of testing, but two of the most commonly used tests are integrated tests and unit tests.

Integrated Tests: This type of testing verifies that different components, modules, or subsystems are working flawlessly together. It ensures that the product works seamlessly across multiple platforms and devices.

Unit Tests: This type of testing focuses on individual units of code. These tests are done to ensure that every piece of code works independently and performs its job as intended.

Unit tests are a crucial tool for developers to ensure that their code works perfectly before being integrated into the final product.

Python unittest Module

As a programming language, Python has its own unit testing framework called unittest. The unittest module is one of Python’s most widely used testing frameworks for testing code.

This module provides a set of tools for constructing and running Python tests, and it also generates reports, detects errors, and facilitates easy debugging. unittest provides developers with numerous methods to conduct various types of testing based on their requirements.

Installation and Importing

The unittest module comes pre-installed with Python, which means that it doesn’t require any installation. However, to use the unittest module in your code, you must import it first.

The following line of code can be used to import the unittest module:

import unittest


The unittest module offers a plethora of methods and assertions that help us check for various outcomes. Let’s take a look at a few of the important ones:

assertEqual(): This method tests whether two values are equal or not.

If the values are not equal, it returns an error message indicating the difference between the two values. unittest.main(): This method runs the test cases in your code by discovering and executing test cases in the specified modules.

It will run all the tests defined in the modules and output the results in the console.


Testing is an essential part of software development, and it is essential to ensure that the software product meets the required standards. The two primary types of testing are integrated tests and unit tests, which help developers identify problems and ensure that software is reliable.

Python’s unittest module provides a wide range of testing tools, and developers can write tests for different requirements while ensuring the reliability of their code. With the use of unittest, developers can identify and prevent errors in the development phase, making the product more efficient and of higher quality.

3) Writing a Unit Test

Unit testing is a methodology that verifies isolated sections of the code. A unit test isolates a part of the code by testing the piece of code in an isolated manner, allowing a developer to determine any bugs and fix them.

In Python, the unittest module facilitates the process of creating, running, and adding test cases to a program. Example Program: List Sum

Let’s assume that we have developed a program that uses a function to add values to a list, and another function that returns the sum of the list values.

To test the functionality of the code, we must create a unit test to test the accuracy of our code. To write a test case using the unittest module, we first need to import the unittest module and create a new class that inherits from unittest.TestCase.

Then, we create test functions by naming them with the prefix “test_” (e.g., test_list). Finally, we execute test functions by using the unittest.main() method.

Creating a Test Case

Let’s create a test case for our list sum example program. We will test two scenarios: one where we pass a list, and the other where we pass a string.

We will name the test case “TestListSum.”


import unittest

class TestListSum(unittest.TestCase):

def test_list(self):

self.assertEqual(sum([1, 2, 3]), 6, “Should be 6”)

def test_string(self):

self.assertEqual(sum(‘abc’), 6, “Should be 6”)



In this test case, we have created two test functions. The first test function, “test_list,” tests whether the sum of a list of elements is correct.

The second test function, “test_string,” tests whether the sum of a string is correct. We are using the assertEqual() method, which compares two values and raises an error if they are not equal.

4) Running Unit Tests on an Application

Running unit tests on an application is an essential part of the software development process. Unit tests help detect errors in code while they are easily fixable.

By identifying and fixing issues earlier on, developers can save time and resources. In Python, running unit tests can be accomplished using the unittest module.

Example Application: Simple Database

Let’s consider an example application of a simple database. A developer would implement a database using a class, with different methods performing CRUD operations on data in the database.

To run unit tests on this simple database, we must first create a test file containing all the test cases.

Writing the Test File

Before we can run tests on the simple database example, we must first write the test file. We will write two test cases to test the functionality of the two methods of our simple database:


from database import Database

import unittest

class TestDatabase(unittest.TestCase):

def setUp(self):

self.database = Database()

def test_insert(self):

self.database.insert(“John”, “Doe”, “23”)

result = self.database.get(“John”)

self.assertEqual(result, (“Doe”, “23”))

def test_remove(self):

self.database.insert(“John”, “Doe”, “23”)


result = self.database.get(“John”)

self.assertEqual(result, None)

if __name__ == ‘__main__’:



In this test file, we import the database class from our simple database Python file. We then create a test class named TestDatabase, which inherits from unittest.TestCase.

We also create a setUp() method, which is called before each test method to initialize our database. Our first test method is called test_insert(), which tests whether inserting values into the database works correctly.

We use the insert() method to insert the values “John,” “Doe,” and “23” into the database. The get() method retrieves the values stored in the database, and we compare the retrieval results with the expected results using the assertEqual() method.

Our second test method is called test_remove(), which tests whether removing values from the database works correctly. We first insert values into the database using the same method as before.

We then remove the value “John” from the database using the remove() method. We again use the get() method to test whether the removal of “John” was successful.

Finally, we use the assertEqual() method to compare the removal results with the expected results.

Recommended Method for Running Unit Tests

To run the unit tests on our simple database, we use the following command in the console:

python -m unittest -v

In this command, -m specifies the argument for the module unittest, and -v provides verbose output (more information about the test run). The name of our file with test cases is


The unittest module is a useful tool that can help developers in program testing. With Python’s unittest module, developers can write test cases to test the functionality of their code accurately.

The unittest module provides methods such as assertEqual() and setUp() to make the workflow easier for developers who have adopted Test-Driven Development (TDD) as their development methodology. By using methods included in unittest, developers can identify problems and prevent errors in the development phase, making the final product more efficient and of higher quality.

In summary, this article has explored the importance of the testing phase in software development, including the two primary types of testing: integrated tests and unit tests. We have also discussed the Python unittest module, including methods, installation, and importing.

Furthermore, we have walked through the steps of writing a unit test, using Python’s unittest module, and the process of running unit tests on an application. By utilizing these tools and methods, developers can detect errors earlier in the development phase, optimize the final product’s efficiency and quality, and reduce costs.

As a result, incorporating unit testing into the software development process is key to producing high-quality code.

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