Adventures in Machine Learning

Testing in Python: A Comprehensive Guide

Testing is an essential part of software development. Without proper testing, it’s impossible to know whether your code is working as expected.

There are different types of testing, and it can be challenging to know which one to use. This article will provide an overview of various testing methods, including automated and manual testing, unit and integration tests, and choosing a test runner.

It will also discuss exploratory testing and making a manual test plan while highlighting the benefits and drawbacks of using manual testing. Automated vs.

Manual Testing

Automated testing involves using software tools to execute pre-scripted tests. These tests are often repetitive and take a long time to execute manually.

Automated testing can be beneficial when you need to run tests frequently, and it can save time and effort. However, automated testing has its limitations and cannot replace manual testing entirely.

Manual testing is the process of manually executing test cases. Manual testing is often used for exploratory testing and is better suited for testing the user interface or user experience.

Manual testing also allows for more flexibility and creativity, and the tester can observe the software’s behavior in real-time. However, manual testing can be time-consuming, and it’s challenging to test every scenario manually.

Unit Tests vs. Integration Tests

Unit tests are tests that verify a single piece of code, such as a function or a method.

Unit tests are often automated and are used to ensure that each unit of code performs its intended function. Unit tests are beneficial because they identify defects early in the development cycle and make it easier to identify problematic code.

Integration tests are tests that verify whether different units of code can work together and integrate correctly. Integration tests are often more complex than unit tests and require more resources.

However, integration testing is essential because it’s often where defects in the software appear. Integration testing can also help identify issues with the software’s architecture or design.

Choosing a Test Runner

There are several test runners available for Python, including unittest, nose, nose2, and pytest. Each of these test runners has its advantages, and the best choice depends on your specific needs.

Unittest is a built-in test runner and is easy to use, while nose and nose2 offer additional features such as test discovery and parallel testing.

Pytest is a robust test runner that can handle complex testing scenarios.

Writing Your First Test

When writing a test, it’s important to start by considering the test structure and what inputs you need. The test must also have an expected result, which allows you to compare the actual result with the expected result.

Writing clear and descriptive test cases can improve the test’s effectiveness and allow for easier debugging when something goes wrong.

Exploratory Testing

Exploratory testing is a type of manual testing that involves exploring software to identify defects and areas for improvement. Exploratory testing is valuable because it allows testers to see the software from the user’s perspective.

Exploratory testing is also beneficial when testing software that is continually changing or evolving.

Making a Manual Test Plan

A manual test plan is a detailed document that outlines the steps taken during manual testing. A test plan can help ensure that each test is performed consistently and accurately.

When creating a manual test plan, it’s important to consider the software’s intended use and potential risks. It’s also essential to document any defects found during testing.

Drawbacks of Manual Testing

Manual testing has several drawbacks compared to automated testing. Manual testing can be repetitive and time-consuming and is more prone to errors.

Manual testing also requires more resources, including personnel and time. However, manual testing still has its place in the software development cycle and can be beneficial when used alongside automated testing.


Testing is a critical aspect of software development, and there are different testing methods available. Automated testing can save time and effort, while manual testing allows for more flexibility and creativity.

Unit tests and integration tests are both essential and have their advantages. When choosing a test runner, it’s essential to consider your specific needs.

Exploratory testing and making a manual test plan can help improve the effectiveness of manual testing. While manual testing has its drawbacks, it’s still an essential part of the software development process.

3) Unit Tests vs. Integration Tests

Definition of Unit Tests

Unit testing is the process of testing individual units or components of a software application in isolation. These units can be a single function, a method, or a small group of functions that work together to perform a specific task.

Unit tests are designed to test the functionality and behavior of a small section of code to ensure it works as it should. The main goal of unit testing is to identify and isolate bugs in code as early as possible.

Definition of Integration Tests

Integration testing is the process of testing how different units of a software application work together. Integration testing can test the communication between different components, databases, and other external systems.

The main goal of integration testing is to verify that the software is working as it was designed and intended to work. Integration testing can help identify defects and issues that may arise when various components are combined.

Difference between Unit and Integration Tests

The primary difference between unit and integration testing is the scope of the test. Unit tests are designed to test individual components of the software in isolation, while integration testing focuses on testing how different components of the software interact with each other.

The scope of unit testing is relatively narrow, and the tests are usually automated. Unit tests are fast to run, and it’s easy to isolate and fix any defects found during the testing process.

Integration testing, on the other hand, is broader in scope and can be more complex than unit testing. Integration testing requires more resources and can take longer to execute.

The integration testing process involves testing different units of software together, which can reveal conflicts between the different components. 4)

Choosing a Test Runner


Unittest is a built-in testing framework and test runner in Python.

It is a popular choice for developers because it’s easy to use and has reliable test discovery features. Unittest is one of the simplest frameworks to learn, and it’s included with every Python installation.

The framework is designed to test unit-level functionality in Python applications. The test-runner is capable of running automated tests, and it’s reliable in catching bugs during test runs.

Unittest is also compatible with the popular PEP framework, which allows it to work well with Continuous Integration/Continuous Deployment systems. Nose/Nose2

Nose and Nose2 are two similar testing frameworks in Python and are known for their compatibility with the standard Python unittest framework.

They offer several features not available in unittest, such as test discovery, parallel test execution, and plugins. Nose and Nose2 are used by professional software development teams and are known to improve testing speed, reduce manual errors, and increase test coverage in code.

They are compatible with Jupyter Notebooks and other dynamic code environments.


Pytest is a popular Python testing framework that provides a more flexible approach to testing compared to Unittest and Nose2.

Pytest is known for its assert statement-based syntax that makes it easy to read and write tests.

This framework allows developers to write small tests that focus on different parts of the system while providing useful feedback about the code base in general.

Pytest also offers advanced features like test filtering and customization of reports.

Pytest is ideal for testing web applications, and it’s highly extendable through plugins.


Choosing the right testing framework and test runner is an essential aspect of software development. Unittest, Nose/Nose2, and

Pytest are three popular testing frameworks that can help developers manage testing their code.

Each testing framework has its strengths and weaknesses, and choosing the right one depends on the specific needs of your software application and team. Unit testing and integration testing both play critical roles in ensuring a software application works as intended, and developers must use both testing techniques together to provide the best possible user experience.


Writing Your First Test

Creating a New Project Folder

Before you can write your first test, you need to set up a new project folder for your code. A well-structured project folder is essential to organize and manage your code files.

To create a new folder, open your file browser and navigate to the location where you want to store your project files. Right-click and select “New Folder.” Give the folder a meaningful and descriptive name, such as “MyProject”.

Creating a Sum Function

Now that you have created a new project folder, it’s time to create your first function. In this example, we will create a sum function that adds two numbers together.

Open your preferred integrated development environment (IDE) and create a new file within your project folder called “”. Within this file, you can create a simple sum function that looks like this:


def sum(x, y):

return x + y


Structuring a Test

After you have created a new function, it’s time to write your first test. The structure of a test can be broken down into three parts: the inputs, the expected result, and the test structure.

The inputs are the parameters that the function will use to perform an operation. The expected result is the output that the function should produce given specific inputs.

It’s essential to structure your tests in a way that is organized and easy to follow. Your tests should be structured in a way that makes it easy to understand what the test is doing and what the expected outcome should be.

It’s common practice to use descriptive names for tests, making it easier for the developer to read the test code and understand what it is testing.

Example Test for Sum Function

Once you have written your sum function, it’s time to create a unit test for it. Follow these steps to create a test file called “” within your project folder.


import math

def test_sum():

assert math.sum(2, 3) == 5

assert math.sum(5, -3) == 2

assert math.sum(0, 1) == 1


In the code above, we have created a new function called `test_sum()` that tests the `sum()` function. The `assert` statement is used to test whether or not the sum function will return the expected output when given specific inputs.

In this example, we are passing the `sum()` function three sets of inputs, and each time, we are testing whether the output is equal to our expected result.


Writing your first test can be an intimidating process, but it’s an essential part of software development. By following the steps outlined in this article, you can create a simple test to verify the functionality of your code.

Remember to structure your test in a way that makes it easy to understand what it is testing and what the expected outcome should be. By testing your code regularly, you can catch errors and bugs early in the development process, saving you time and resources in the long run.

In this article, we discussed various essential aspects of software testing, including automated and manual testing, unit and integration tests, and choosing a test runner. We also explored how to write your first test, including creating a project folder, structuring the test, and an example test for the sum function.

The key takeaway from this article is that software testing is an essential part of software development, which can help identify and isolate bugs in code as early as possible, save time, and increase the overall quality of software. Regular software testing can catch errors and bugs early in the development process, saving you time and resources in the long run.

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