The Basics of Smoke Testing and Sanity Testing

In the world of software development, ensuring the quality and stability of an application is paramount. Various testing techniques are employed throughout the software development life cycle to achieve this goal. Among these, smoke testing and sanity testing are essential for detecting critical issues early in the process. While they share some similarities, they have distinct purposes and applications. This article will explore the fundamentals of smoke testing and sanity testing, helping you understand when and why each is used.

What is Smoke Testing?

Smoke testing, also known as build verification testing, is a preliminary check performed on a software build to determine whether the most crucial functionalities are working as expected. The name “smoke testing” comes from the hardware industry, where engineers would turn on a device for the first time and look for smoke to indicate a major malfunction. In the context of software, smoke testing serves as an initial gatekeeper to identify any major issues before more comprehensive testing is conducted.

Key Characteristics of Smoke Testing:

• Basic Checks: Smoke testing involves running a set of basic tests that verify the core functionalities of the software. For example, if you are testing a web application, this might include verifying that the login works, the main pages load correctly, and basic user interactions function.
• Quick and High-Level: This type of testing is designed to be fast and does not go into detailed examination. The goal is to catch major flaws early, saving time and effort by preventing further testing of a potentially unstable build.
• Performed Frequently: Smoke tests are run every time a new build is created to make sure the software is stable enough for more thorough testing.
• Automated or Manual: Smoke tests can be automated using tools like Selenium, making it easier to execute them on a regular basis. However, manual testing is also common for this type of check, especially in smaller projects.

What is Sanity Testing?

Sanity testing is a focused type of testing conducted to verify that specific functions of the software are working as intended after changes have been made. It is typically performed after receiving a new build with minor bug fixes or updates. Unlike smoke testing, which is broad and checks for overall stability, sanity testing dives deeper into specific functionalities to ensure they work correctly after changes.

Key Characteristics of Sanity Testing:

• Focused Testing: Sanity tests target specific parts of the application affected by recent changes, such as new features, updates, or bug fixes.
• Narrow Scope: The scope of sanity testing is narrower than that of smoke testing. While smoke testing checks for overall stability, sanity testing ensures that specific issues have been addressed and that related functions are functioning properly.
• Quick Validation: Sanity testing is meant to be a quick validation process that does not require extensive documentation or detailed test scripts.
• Manual in Nature: Sanity tests are often performed manually as they are conducted by testers to confirm that a particular fix or change behaves as expected. Automated scripts can also be created for repeated sanity tests, but the approach is more case-specific.

Differences Between Smoke Testing and Sanity Testing

While smoke testing and sanity testing are sometimes used interchangeably, there are important distinctions between the two:

Aspect	Smoke Testing	Sanity Testing
Purpose	To ensure the basic functionality of the software.	To verify that specific changes are working as intended.
Scope	Broad; tests the overall stability of the application.	Narrow; focuses on specific functionalities affected by updates.
When to Perform	Performed on initial builds before detailed testing.	Performed after receiving a new build with bug fixes or changes.
Depth	High-level, shallow testing.	More detailed but still targeted.
Test Coverage	Checks core functionalities.	Checks specific areas related to changes.
Automation	Can be automated for regular use.	Often manual but can be automated for repeated tests.

When to Use Smoke and Sanity Testing

Smoke Testing:

• When a new build is deployed: Smoke tests should be run immediately after a new build is delivered to ensure that the application is stable enough to move forward with detailed testing.
• In continuous integration (CI): Smoke testing is often integrated into CI pipelines, ensuring that any new code changes don’t break critical functionality.
• Initial build verification: Before extensive testing begins, smoke testing confirms that major functionalities are in place.

Sanity Testing:

• After minor code changes: Sanity testing is most commonly used after a patch or bug fix has been applied to ensure that the changes have not affected the existing functionality.
• When time is limited: When comprehensive regression testing isn’t feasible, sanity testing can help validate that the immediate changes are functioning as expected.
• Before detailed functional testing: Ensuring that specific updates are working properly can be a prerequisite for more thorough functional or integration tests.

The Importance of Smoke and Sanity Testing

Both smoke and sanity testing play crucial roles in the software development lifecycle. They act as gatekeepers to identify significant issues early and ensure that the software’s most essential functions are stable before deeper testing. This not only saves time and resources but also helps maintain a smoother and more efficient development process.

Conclusion