Key Differences Between Smoke Testing and Regression Testing

Testlio

August 16th, 2024

Smoke testing and regression testing play crucial roles in ensuring the functionality and reliability of software applications. Although both test software’s functionality, their purposes differ, and they occur at different stages of development. Understanding the differences between these two testing types can help effectively manage and maintain software quality. 

In this article, we will cover smoke testing and regression testing, their primary objectives, and how and when each testing type is conducted. We will also examine the benefits of each testing type and the scenarios where they are most effective.

What is Smoke Testing?

Smoke testing involves running a set of basic tests on a new build to verify that the software’s most crucial functions are working as expected. If the build passes these tests, it is considered stable enough for more detailed testing. It’s often called “build verification” or “confidence testing.”

By identifying major issues early in the development cycle, smoke testing helps prevent more significant problems later on. It provides immediate feedback to developers, allowing them to address any critical issues before proceeding with more extensive testing.

Purpose of Smoke Testing

The main objective of smoke testing in software development is to ensure that the critical features of an application are functional and stable enough for further testing. Here are the key objectives:

• Verify Critical Features: Ensure essential features like launching, logging in, and basic navigation work as expected.
• Ensure Stability: Confirm the build is stable enough for further testing, identifying critical issues early.
• Act as a Gatekeeper: Prevent unstable software versions from progressing, maintaining quality and reliability.
• Provide Quick Feedback: Offer immediate feedback to developers to address critical issues promptly.
• Execute After Every Build: Conduct tests after each build or deployment to ensure changes don’t break existing functionality.

Benefits of Smoke Testing

Smoke testing offers several advantages in software development by ensuring critical issues are detected early and promptly addressed. 

Here are some of the key benefits:

• Early Detection of Major Issues: Identifies significant problems early, preventing complications and delays.
• Time and Effort Savings: Saves time by addressing critical defects promptly, reducing extensive debugging later.
• Improved Stability: Ensures basic functionalities work correctly, providing a stable foundation for further testing.
• Efficient Resource Utilization: Focus resources on stable builds, improving testing efficiency.
• Quick Feedback Loop: Provides immediate feedback, promoting continuous improvement.
• Confidence Building: Builds confidence in core functionalities, supporting a positive outlook for detailed testing.

Automating Smoke Tests

Software applications may require more than manual smoke testing to handle frequent and repetitive testing.  Automation offers several advantages:

Handling Complexity and Frequency

As software applications grow more complex, the number of critical functionalities that need to be tested increases. Manual smoke testing can become time-consuming and error-prone, especially when tests must be run frequently after each build or deployment.

Business Continuity

Automating smoke tests ensures that business-critical features are tested regularly and function as intended, preventing disruptions to business continuity. 

Reducing Human Errors

Automation reduces the risk of human errors that can occur during manual testing. Automated tests provide consistent and reliable results, allowing tests to be run consistently.

Efficiency and Speed

Automation enables the quick and efficient execution of smoke tests on various platforms and configurations. Automated tests can run simultaneously across different environments, significantly speeding up the testing process.

Resource Optimization

By automating repetitive, straightforward smoke tests, testers can focus on more complex and critical testing scenarios. This allows for better utilization of human resources, as testers can dedicate their time to tasks that require more in-depth analysis and creativity.

Continuous Integration and Continuous Deployment (CI/CD)

Automation is essential for CI/CD pipelines, where frequent builds and deployments are standard. Automated smoke tests can be integrated into the CI/CD pipeline, providing immediate feedback on the stability of each new build.

By automating smoke tests, development teams can verify critical functionalities consistently, allowing for a more efficient and reliable testing process. This ultimately leads to higher-quality software and faster delivery times. 

However, it’s important to note that automation of smoke testing is better suited to the happy path. To ensure reliability, your scripts must be updated as new changes are introduced. This includes updating test data, modifying logic and assertions, and adjusting test flows.

Example Test Case: Verify Password Reset

Objective: Ensure users can reset their passwords using the password reset feature.

Steps:

1. Open the Application: Launch the web application in a browser.
2. Navigate to the Login Page: Click on the “Login” button or link to the login page.
3. Click on “Forgot Password”: Click on the “Forgot Password” link to navigate to the password reset page.
4. Enter Registered Email: Input a registered email address in the provided field.
5. Submit Request: Click on the “Submit” button to request a password reset.
6. Check Email: Verify that a password reset email is received.
7. Follow Reset Link: Click on the link provided in the email to navigate to the password reset page.
8. Enter New Password: Input a new password and confirm it.
9. Submit New Password: Click on the “Reset Password” button.
10. Verify Successful Reset: Check if the user receives a confirmation message and can log in with the new password.

Expected Result: The user should be able to reset their password successfully and log in with the new password.

Running this smoke test after each build can detect any issues with the password reset functionality early. For example, if a recent code change affects the password reset process, it will be caught immediately.

Consider the case where a new security feature, such as two-factor authentication (2FA), is added to the application. After implementing this feature, the smoke test for the password reset functionality is executed. 

If the new feature inadvertently affects the password reset process, the smoke test will fail, alerting the developers to the issue. They can then fix the problem before it impacts users or progresses to more extensive testing phases.

What is Regression Testing?

Regression testing is a type of software testing that ensures recent code changes have not adversely affected the application’s existing functionalities. It is a crucial part of the software development process, aimed at verifying that the software continues to perform correctly after modifications such as enhancements, bug fixes, or configuration changes.

Purpose of Regression Testing

Regression testing is a crucial aspect of software maintenance and quality assurance. It involves retesting the software after modifications to ensure that new changes have not adversely affected the existing functionality. 

This type of testing is essential for maintaining the stability and reliability of the software over time. The purpose of regression testing is as follows:

• Identifying Defects or Errors: Regression testing aims to identify any defects or errors that may have been introduced after code changes. This ensures that the software’s overall functionality remains intact. 
• Ensuring Software Stability: Regression testing is typically performed after significant changes, such as bug fixes, enhancements, or new feature additions. This is crucial to ensure that the software as a whole is still functioning correctly. It helps verify that the recent changes have yet to introduce new bugs or issues into the system.
• Retesting and Creating New Test Cases: Regression testing focuses on retesting previously executed test cases to ensure the existing functionality is not broken. Additionally, it includes creating new test cases to cover the areas affected by the changes. This comprehensive approach helps maintain the software’s quality and reliability.

Benefits of Regression Testing

Regression testing plays an important role in maintaining the quality and integrity of software. Here’s how it helps:

• Mitigating the Risk of Unintentional Bugs: Regression testing helps identify and mitigate the risk of unintentional bugs or issues introduced after code changes. Retesting existing functionality ensures that new changes haven’t adversely affected the software.
• Ensuring Stability and Reliability: One of the primary benefits of regression testing is ensuring the stability and reliability of the software. It verifies that new changes maintain existing functionality and a consistent user experience.
• Maintaining User Confidence: Regular regression testing helps maintain user confidence. When users know that the software is thoroughly tested after each update, they are more likely to trust and rely on it.
• Preventing Regression Defects from Reaching End-Users: Regression testing prevents regression defects from reaching end-users, improving overall software quality and reducing the risk of negative user experience.

By incorporating regression testing into the development process, teams can ensure that their software remains stable, reliable, and user-friendly. This will ultimately lead to higher-quality products and satisfied users.

Automated Regression Testing

Test automation is crucial in Regression Testing, especially for complex and large software applications. Here are the benefits of regression test automation:

• Efficiency: Manual testing can be time-consuming and prone to human error, especially when dealing with extensive test cases. Automation allows for faster execution of tests, saving time and resources.
• Consistency: Automated tests are executed in the same manner every time, ensuring consistent results and reducing the risk of oversight.
• Coverage: Automation enables comprehensive testing by covering more test cases and scenarios than feasible manually, ensuring that all aspects of the application are tested.
• Reusability: Automated test scripts can be reused across different application versions, making it easier to maintain and update tests as the software evolves.
• Repeated Execution: Automation tools can run regression tests repeatedly, ensuring that new changes do not introduce defects to the existing functionality.
• Faster Feedback: Automated tests provide quick feedback to developers, allowing them to identify and fix issues promptly. This is particularly important in agile development environments where rapid iterations are common.
• Early Detection of Issues: Automated tests can be run frequently to identify potential issues early in the development cycle, reducing later costs and efforts.
• Resource Optimization: Automation frees human testers to focus on more complex and exploratory testing tasks, optimizing testing resources.

Example Test Case: Banking Application – Fund Transfer

Let’s consider an example of a fund transfer feature in a banking application. Suppose the development team has recently added a new feature that allows users to schedule future fund transfers. Here’s how regression testing can prove its value:

Test Scenario: Scheduling Future Fund Transfers

Initial Functionality:

• Users can transfer funds between their own accounts.
• Users can transfer funds to other users’ accounts within the same bank.
• Users can view their transaction history.

New Feature:

• Users can now schedule fund transfers for a future date.

Regression Test Case

Test Case ID: RT-002

Title: Verify that the fund transfer initial functionalities remain intact after adding the scheduled transfer feature.

Preconditions:

• User is logged into the banking application.
• User has sufficient balance in one’s account.

Test Steps:

1. Navigate to the fund transfer page.
2. Verify that the user can transfer funds between their own accounts immediately.
3. Verify that the user can immediately transfer funds to another user’s account within the same bank.
4. Schedule a fund transfer for a future date between the user’s own accounts.
5. Verify that the scheduled transfer is listed correctly in the scheduled transactions.
6. Schedule a fund transfer for a future date to another user’s account within the same bank.
7. Verify that the scheduled transfer is listed correctly in the scheduled transactions.
8. Check the transaction history to ensure that immediate transfers are recorded correctly.
9. Verify that the scheduled transfers are executed correctly on the specified future dates.

Expected Results:

• Immediate fund transfers between the user’s own accounts and to other users’ accounts within the same bank should work correctly.
• Scheduled fund transfers should be listed correctly in the scheduled transactions.
• The transaction history should accurately reflect immediate transfers.
• Scheduled transfers should be executed correctly on the specified future dates.

Regression testing proves its value by ensuring that the core functionality of fund transfers (immediate transfers and transaction history) remains intact after the new scheduled transfer feature is introduced. It also helps detect any defects that may have been introduced due to the new feature, such as issues with immediate transfers, incorrect scheduling, or execution of future transfers.

By running this regression test case, the team can confidently release the new feature, knowing that it has not negatively impacted the application’s existing functionality.

Smoke Testing Vs Regression Testing

Key Takeaways

Smoke testing and regression testing are integral to maintaining software quality at different stages of development. Smoke testing, often termed “build verification testing,” is a preliminary check to ensure the most critical functions of a new build are stable enough for further testing. This test is routinely performed after each build to catch significant issues swiftly, setting a foundation for more detailed assessments.

On the other hand, regression testing is comprehensive, ensuring that recent changes haven’t adversely affected existing functionalities. It’s usually conducted following updates to confirm that the system remains stable and that the new modifications integrate without disrupting the overall software performance.

For businesses looking to improve product quality and accelerate market readiness, partnering with an experienced provider like Testlio can help. Testlio offers both smoke and regression testing services, utilizing a combination of automated tools and expert testers to identify critical issues early and ensure the integrity of systems across updates.