Smoke testing : Ensuring basic functionality

Imagine running a Python project without a requirements.txt file. Just as you rely on these checks to ensure everything runs fine, smoke tests are performed to confirm that your code is ready for the next phase.

In this blog we will dive deeper into the world of smoke testing.

What is Smoke Testing

Smoke Testing, often referred to as "build verification testing", is a type of software testing that verifies whether the major functionalities of an application are working correctly after a new build. It's like performing a quick "sanity check" to ensure the product is stable enough for further, more detailed testing.

📌 Think of it as turning on a newly built car engine just to see if it starts — you're not taking it for a spin yet.

Smoke tests assess whether the essential functionalities of an application or system are operating correctly. For instance:

• Does the software launch without issues?

• Can the user successfully log in?

• Are the primary features available and functional?

Key Functions of Smoke Testing:

• Verifying Build Stability: Smoke tests confirm that the software build is stable and that there are no major issues that would prevent further testing.

• Detecting Showstopper Bugs: The primary goal is to identify critical issues early on, which could halt the progress of the project.

• Saving Time and Resources: By catching major defects early, smoke testing helps avoid wasting time on a flawed build.

Why Do We Need Smoke Testing?

Smoke testing is essential for several reasons, all of which contribute to a smoother, more efficient development process.

1. Early Detection of Critical Issues

Smoke testing acts as the first filter to catch critical defects in the software and to address them before they cause more complex problems down the line.

2. Increased Efficiency in Development

Smoke testing ensures that only stable builds proceed to more detailed testing phases as teams might waste valuable time and resources conducting in-depth testing on a build that has fundamental issues.

3. Improved Quality Assurance

Smoke testing adds an additional layer of quality assurance by ensuring that the most basic and crucial functionalities work as intended to build confidence in the overall stability of the application.

4. Faster Feedback Loop

By incorporating smoke testing into your development process, you create a faster feedback loop. Developers can quickly determine whether a build is viable or needs immediate attention, allowing for more agile and responsive development.

5. Gatekeeper to Further Testing

Smoke testing acts as a filter or gatekeeper. If the build fails smoke tests, it’s returned to the developers for fixes. If it passes, it proceeds to comprehensive testing like unit tests, functional testing, or acceptance testing.

Goal of Smoke Testing

The purpose of performing smoke tests isn’t to validate every functionality, but to ensure that the application is stable enough for deeper testing. Here are the detailed goals:

• Early Identification of Critical Issues
  By verifying critical paths (like logins, data fetches, and API calls) right after deployment, smoke testing allows teams to catch major bugs or configuration issues early, before wasting time on deeper QA efforts.

• Validate Major Functionalities
  Smoke tests confirm that high-priority features are functioning as expected. For example, in a mobile app, the smoke test might check whether the app launches, users can log in, and the main menu renders correctly, all critical functionalities for user access.

• Minimize Wasted QA Time
  Instead of proceeding with hundreds of regression or exploratory test cases, QA teams first run smoke tests. If these fail, the build is immediately rejected, saving hours (or days) of unnecessary testing on a broken build.

• Serve as a Quality Checkpoint
  A passed smoke test essentially gives the green light that the build is stable and ready for detailed testing. It plays a crucial role in release management, acting as the first checkpoint in the software quality assurance (QA) pipeline.

When and Who Performs Smoke Testing?

Let’s break down the timeline and roles associated with smoke testing:

When Is Smoke Testing Performed?

• After Every New Build Deployment
  As soon as a new build is pushed to a QA or staging environment, a smoke test is run to validate its basic stability.

• Before Regression or System Testing
  It acts as a gatekeeper before more extensive test suites are executed.

• During Continuous Integration Pipelines
  In CI/CD environments, smoke tests are triggered automatically to ensure the build can safely move to the next pipeline stage.

Who Performs Smoke Testing?

• QA Engineers
  Responsible for executing manual or automated smoke tests, especially in structured testing teams.

• Developers
  Often run basic unit-level smoke tests to check if their code breaks the application before passing it to QA.

• Automation Engineers
  In CI/CD pipelines, automation engineers script smoke test suites that run with every build commit or PR merge.

Why You Need Smoke Tests

If you're still unsure about implementing smoke tests in your software development workflow, here are key reasons why you must:

• Catch Major Issues Quickly
  A broken login page, crashing app, or unreachable API should never make it to production. Smoke testing ensures that these showstopper issues are caught early.

• Maintain Stability in Rapid Development
  In modern agile and DevOps workflows, multiple code changes are made daily. Smoke tests act as a quick quality assurance checkpoint before going deeper.

• Validate Critical Paths First
  Core workflows like login, dashboard access, and data fetching are vital for users. Smoke testing ensures these are always functional, even when smaller bugs are present.

• Support Agile and Continuous Delivery
  Smoke tests provide immediate feedback on the build status and integrate well with continuous deployment and automated testing tools.

• Improve Product Quality with Less Effort
  Smoke testing is low effort, high return catching critical bugs early reduces the cost and time associated with fixing them later.

Real-World Scenario: The Launch of a New Mobile Banking App

Imagine you're a developer working on a new mobile banking app. This app is designed to handle everything from simple balance checks to complex transactions like fund transfers and bill payments.

Before releasing a new build for extensive testing or for use by beta testers, you need to ensure that the core functions are operational. This is where smoke testing comes into play.

Steps to apply smoke testing

1. Core Functions Check:

   • User Login: First, you check if users can log in securely. Without a functional login system, users cannot access the app, rendering all other features useless.

   • Balance Check: Next, verify that users can view their account balance. This is one of the most fundamental features of any banking app.

   • Fund Transfer: Ensure that the fund transfer functionality is working, as this is a critical transaction process that must not fail.

2. Basic Navigation:

   • Menu Navigation: Test if users can navigate through the app's menu to reach different sections like "Account Summary," "Transaction History," and "Settings."

   • Notifications: Check if the app sends essential notifications, such as low balance alerts or payment due reminders, to the user.

3. Stability Verification:

   • No Crashes: The app must not crash during these basic operations. A stable build is essential before moving on to more detailed testing.

Types of Smoke Testing

1. Build Verification Testing (BVT):

• Overview:

  • Build Verification Testing, often considered synonymous with smoke testing, involves verifying the integrity of the build. It ensures that the critical functionalities of the software are operational after the build process.

• When to Use:

  • Perform BVT immediately after a new build is created to catch any major issues before they propagate further into the testing cycle.

• Example:

  • In a healthcare application, BVT would ensure that core functions like patient registration, appointment scheduling, and medical record access are all working before moving forward.

2. Sanity Smoke Testing:

• Overview:

  • Sanity smoke testing is a narrow, focused test performed after receiving a software build with minor changes or bug fixes. It checks whether the specific functionality that was recently added or fixed is working as expected.

• When to Use:

  • Use this type of smoke testing when you receive a build that includes minor changes or bug fixes, ensuring those updates haven't broken existing functionality.

• Example:

  • After fixing a bug in an e-learning platform’s quiz module, sanity smoke testing would check if the quiz functionality is now working correctly without affecting the rest of the system.

3. Acceptance Smoke Testing:

• Overview:

  • Acceptance smoke testing is performed to determine whether the software meets the acceptance criteria defined by stakeholders. It’s usually done before the software is handed over for user acceptance testing (UAT).

• When to Use:

  • Use this before transitioning to UAT to confirm that the software meets the basic requirements and is ready for more thorough testing by the end users.

• Example:

  • For a retail application, acceptance smoke testing would ensure that users can browse products, add items to the cart, and complete the checkout process without any issues.

4. Manual Smoke Testing:

• Overview:

  • Manual smoke testing involves testers manually executing test cases to verify the basic functionalities of the software. This type is often used when automation isn’t feasible or when the software is in the early stages of development.

• When to Use:

  • Use manual smoke testing when you need to test user interfaces, new features, or complex workflows that require human observation.

• Example:

  • A banking application might undergo manual smoke testing to ensure that users can log in, view their account balances, and perform transactions correctly.

5. Automated Smoke Testing:

• Overview:

  • Automated smoke testing uses scripts and tools to automatically execute test cases, making it faster and more efficient than manual testing. It’s particularly useful for large projects with frequent builds.

• When to Use:

  • Use automated smoke testing in continuous integration/continuous deployment (CI/CD) pipelines to quickly validate each build.

• Example:

  • In a CI/CD environment, an automated smoke test could run after every code commit, checking if core functions like login, data retrieval, and API endpoints are working correctly.

How Can the Smoke Testing Procedure Be Automated?

Automating smoke tests enhances efficiency, consistency, and speed, especially in CI/CD pipelines. Here's how you can do it:

1. Identify Critical Test Cases
   Choose high-priority test cases that cover the most critical functionalities of the application (e.g., login, database connection, dashboard load).

2. Use Automation Tools
   Implement tools like Selenium, Keploy, Cypress, Playwright, or JUnit/TestNG. These tools support scripting and scheduling automated smoke tests.

3. Integrate with CI/CD Pipelines
   Integrate your smoke test scripts into CI tools like Jenkins, GitLab CI, CircleCI, or GitHub Actions so tests run automatically on every code push or pull request.

4. Generate Reports Automatically
   Use reporting tools like Allure, ExtentReports, or native test framework reports to get real-time feedback on build health and test results.

Smoke Testing vs. Sanity Testing

Smoke testing and sanity testing are both surface-level testing techniques used to validate builds but they serve different purposes at different stages of the testing process. Let’s explore each.

What is Sanity Testing?

Sanity testing is a narrow and focused testing approach performed after minor bug fixes or changes to ensure that specific functionalities are working as expected without introducing new issues.

Key Characteristics:

• Focus: Validates a small section of functionality (e.g., checking if a fixed login issue now works).

• Scope: Narrow and deep.

• Performed After: Minor code changes or patches.

• Speed: Quick but targeted.

• Who Performs It: QA engineers or testers.

• Test Basis: Often undocumented or informal.

• Objective: To validate the correctness of newly added functionality or bug fixes without conducting a full regression cycle.

Differences Between Sanity Testing and Smoke Testing

Both types of tests are non-exhaustive and aim to save time but they are applied in different scenarios during the software testing life cycle.

Smoke Testing vs. Regression Testing

While smoke testing checks if the application is stable enough for further testing, regression testing ensures that newly introduced changes haven't broken existing features.

Key Differences:

Summary:

• Use smoke testing as an entry point to testing.

• Use sanity testing after small fixes or updates.

• Use regression testing to maintain long-term application reliability.

Advantages of Smoke Testing

Smoke testing offers several advantages that enhance both development and QA efficiency:

• Early Detection of Critical Bugs
  Smoke tests are designed to surface showstopper bugs quickly. This allows developers to respond and fix them before the code reaches users or deeper testing layers.

• Time and Resource Efficient
  Since smoke testing is shallow, it can be completed in minutes (especially when automated). This means developers and testers get fast feedback without spending time running full test suites.

• Improves Software Stability
  Regular smoke testing ensures that the core application behavior remains stable across builds. This is critical in agile environments with frequent code changes and tight delivery deadlines.

• Supports Continuous Integration (CI)
  Automated smoke tests can be integrated into CI tools like Jenkins, GitHub Actions, or GitLab CI/CD. This allows each build to be validated automatically before being promoted to further environments.

• Avoids Testing Broken Builds
  By validating build health at the very beginning, QA teams can skip deeper test cases when the core system is already failing, resulting in improved efficiency.

• Improves Confidence in Releases
  By consistently passing smoke tests, development teams gain more confidence in code quality and deployment readiness.

Disadvantages of Smoke Testing

While useful, smoke testing has limitations that make it unsuitable as a standalone QA strategy:

• Limited Scope
  Smoke testing does not go in-depth. It covers only major functionalities, which means edge cases, minor bugs, or UI glitches may be missed entirely.

• Potential to Miss Critical Bugs
  Because it avoids detailed scenarios, smoke tests may overlook small issues that could become major bugs in specific user workflows.

• Over-Reliance Can Be Risky
  Treating smoke testing as a replacement for unit testing, functional testing, or regression testing is dangerous. It gives a false sense of security about the health of the software.

• Not a Comprehensive Testing Solution
  Smoke testing does not verify business logic, UI consistency, or performance. It must be part of a multi-layered testing strategy.

Best Practices for Effective Smoke Testing

1. Automate whenever possible :

   • Automate your smoke tests to save time and increase accuracy, especially in CI/CD pipelines.

2. Run Tests Early and Often:

   • Perform smoke testing early in the development process and after every major code change to catch issues as soon as they arise.

3. Keep Tests Simple:

   • Focus on testing only the most critical functionalities. Smoke testing should be quick and not too detailed.

4. Use the Right Tools:

   • Choose tools that fit your project’s needs, such as Selenium for automated web application smoke tests or Jenkins for CI/CD pipelines.

Involve the Entire Team:

• Make smoke testing a collaborative effort by involving developers, testers, and stakeholders in the process.

Comparison of smoke testing with other testing types

Tools to Automate Smoke Testing: A Developer's Essential Guide

When it comes to streamlining your software development process, automating smoke tests is a game-changer. Not only does it save time, but it also ensures consistency and reliability in your testing efforts. In this section, we’ll explore some of the top tools you can use to automate smoke testing and enhance your CI/CD pipelines.

1. Keploy

Keploy is an open-source testing toolkit designed to automatically generate tests based on real-world application usage. It is particularly effective for smoke testing, providing a way to ensure that critical functionalities are operational in new builds by leveraging actual user interactions.

Key Features:

• Automated Test Generation:

  • Automatically generates test cases from observed network traffic, reducing the manual effort required to create smoke tests.

• Test Replay and Validation:

  • Captures and replays application behavior across different environments, ensuring that key functionalities perform as expected.

• CI/CD Integration:

  • Seamlessly integrates with CI/CD pipelines, enabling automated smoke tests after each build or deployment.

• Real-World Observability:

  • Generates tests based on real user interactions, ensuring that smoke tests are highly relevant and effective in catching potential issues.

2. Selenium

Selenium is a widely-used open-source tool that allows developers to automate web applications across different browsers. It’s ideal for automating smoke tests for web applications, ensuring that critical functionalities like login forms, user navigation, and data submissions work flawlessly.

• Key Features:

  • Supports multiple programming languages (Java, Python, C#, etc.).

  • Integrates with CI/CD tools like Jenkins.

  • Provides cross-browser testing capabilities.

Why Selenium for Smoke Testing? Selenium’s flexibility and extensive community support make it a top choice for automating smoke tests, especially in environments where web applications are the focus.

3. Jenkins

Jenkins is a continuous integration tool that automates the build process, including smoke testing.

Why Jenkins for Smoke Testing? Jenkins is the backbone of many CI/CD pipelines, making it an excellent tool for integrating automated smoke tests into your development workflow.

• Key Features:

  • Easily integrates with various testing frameworks like JUnit and TestNG.

  • Extensive plugin support for customising your CI/CD pipeline.

  • Provides real-time feedback on test results.

4. TestNG

TestNG is a powerful testing framework inspired by JUnit but with more features, such as parallel testing and flexible test configurations.

Why TestNG for Smoke Testing? TestNG’s ability to organize and run tests efficiently makes it a strong candidate for automating smoke tests, especially when combined with Selenium.

• Key Features:

  • Supports annotations for easier test management.

  • Provides detailed reporting and logging.

  • Can be integrated with Selenium for UI smoke tests.

5. PyTest

PyTest is a popular testing framework for Python applications, known for its simplicity and scalability.

Why PyTest for Smoke Testing? For Python-based projects, PyTest is a natural choice for automating smoke tests due to its ease of use and robust feature set.

• Key Features:

  • Easy setup with minimal boilerplate code.

  • Supports parallel test execution.

  • Integrates seamlessly with CI tools like Jenkins.

Conclusion

Smoke testing is an essential part of modern software quality assurance. Whether you’re building a mobile app, an enterprise platform, or a microservice architecture, smoke tests offer a cost-effective, fast, and reliable way to ensure you’re not pushing broken builds forward. Smoke testing helps you identify and reinforce weak links early, leading to a more robust and reliable product. So, make smoke testing an integral part of your development process and watch as it helps pave the way for smoother, more successful projects.

Frequently Asked Question

What is smoke testing in software development?

Smoke testing is a preliminary testing phase that verifies whether the core functionalities of an application or system work properly. It acts as a sanity check to ensure that the build is stable enough for further testing.

How does smoke testing differ from regression testing?

Smoke testing focuses on verifying the basic, critical functionalities of a build, ensuring the system is stable enough for more detailed testing. Regression testing, on the other hand, checks that new code changes haven't negatively impacted existing functionality, covering a wider scope.

When should smoke testing be performed?

Smoke testing should be performed immediately after a new build is created before more extensive testing begins. It ensures that major issues are identified early in the development process, allowing teams to address them before proceeding further.

Can smoke testing be automated?

Yes, smoke testing can be automated using tools like Selenium, Keploy, Jenkins, and PyTest. Automating smoke tests can save time, increase consistency, and integrate seamlessly into CI/CD pipelines for continuous testing.

What are the key benefits of smoke testing?

The main benefits of smoke testing include early detection of critical issues, improved development efficiency, enhanced quality assurance, and a faster feedback loop, all of which contribute to a smoother development process.

What types of smoke testing are there?

There are several types of smoke testing, including Build Verification Testing (BVT), Sanity Smoke Testing, Acceptance Smoke Testing, Manual Smoke Testing, and Automated Smoke Testing. Each type serves a specific purpose, depending on the development phase and the nature of the build.