Overview

In the realm of Manual Testing, understanding the difference between smoke testing and sanity testing is crucial. Both are types of software testing used to identify bugs in the early stages of software development but serve distinct purposes. Smoke testing is a preliminary test to check the basic functionality of the application, whereas sanity testing is a more focused test to verify specific functionalities after minor changes or fixes.

Key Concepts

1. Purpose and Scope: Understanding the main goals and the scope covered by each testing type.
2. Execution Timeframe: Knowing when to perform smoke and sanity testing during the software development lifecycle.
3. Test Depth and Focus: Recognizing the level of depth and areas of focus for each testing type.

Common Interview Questions

Basic Level

1. What is smoke testing and when is it performed?
2. Can you explain what sanity testing is and its purpose?

Intermediate Level

3. How do smoke testing and sanity testing differ in their execution?

Advanced Level

4. Discuss the importance of smoke and sanity testing in continuous integration systems.

Detailed Answers

1. What is smoke testing and when is it performed?

Answer: Smoke testing, also known as "build verification testing," is a type of software testing that examines whether the most critical functions of a software application are working. It's usually the first test conducted after a new build is received, aiming to ensure the stability of the build for further testing. If the application fails the smoke test, it is rejected, and the development team is notified to fix the issues.

Key Points:
- Smoke testing is a broad approach, covering all the major functionalities of the application but not going into deep.
- It's typically executed by testers immediately after a software build is made.
- The primary aim is to ascertain that the critical functionalities are working and that the build is stable enough for further testing.

Example:

// Example of a simple smoke test for a web application login feature

public void TestLoginFunctionality()
{
    NavigateToLoginPage();  // Navigate to the login page
    EnterCredentials("testUser", "testPassword");  // Enter valid credentials
    ClickLoginButton();  // Attempt to login

    // Verify if the login was successful by checking if the user is redirected to the homepage
    Assert.IsTrue(IsHomePageDisplayed(), "The home page should be displayed after successful login.");
}

2. Can you explain what sanity testing is and its purpose?

Answer: Sanity testing is a subset of regression testing performed after receiving a software build with minor changes or fixes. Its purpose is to verify that the changes or fixes have been correctly implemented and have not adversely affected existing functionalities. Sanity testing is focused, usually not documented, and is aimed at checking the functionality of particular features rather than the whole application.

Key Points:
- Sanity testing is more narrow and focused compared to smoke testing.
- It's performed after regression testing to verify specific functionalities affected by recent code changes.
- Sanity testing helps in quickly identifying issues in the functionalities that were supposed to be fixed or modified.

Example:

// Example of a sanity test for checking a new feature in an email application

public void TestEmailDraftFeature()
{
    ComposeNewEmail();  // Start composing a new email
    AddRecipients("test@example.com");  // Add a recipient
    WriteEmailBody("Hello, this is a test email.");  // Write a simple message
    SaveAsDraft();  // Save the email as a draft

    // Verify if the draft is saved and can be reopened
    Assert.IsTrue(IsDraftSavedAndReopenable(), "The draft should be saved and reopenable.");
}

3. How do smoke testing and sanity testing differ in their execution?

Answer: The key difference in execution between smoke and sanity testing lies in their scope, focus, and when they are performed. Smoke testing is broader, covering all major functionalities to ensure the build is stable for further testing. It's usually the first test on a new build. Sanity testing, on the other hand, is more focused and performed later, often after regression testing, to validate specific functionalities or fixes in the application.

Key Points:
- Smoke testing is broad and shallow, while sanity testing is narrow and deep.
- Smoke testing is performed earlier to validate the stability of the build, whereas sanity testing is done later to check the correctness of specific functionalities.
- Sanity testing is usually unscripted and focused on specific areas, unlike smoke testing, which covers major functionalities.

Example:

// No direct C# code example for execution differences. This response requires conceptual understanding rather than code demonstration.

4. Discuss the importance of smoke and sanity testing in continuous integration systems.

Answer: In continuous integration (CI) systems, both smoke and sanity testing play vital roles in maintaining code quality and ensuring rapid feedback on the health of the application. Smoke testing allows for quick identification of any critical issues with new builds, ensuring that only stable builds proceed through the CI pipeline. Sanity testing, on the other hand, ensures that specific, recent changes have not introduced new issues and that the application's functionality remains intact.

Key Points:
- Smoke testing serves as a gatekeeper in CI, ensuring that only stable builds are promoted for further testing.
- Sanity testing provides quick verification of specific changes, making it efficient for CI environments where changes are frequent and need to be validated quickly.
- Both testing types aid in identifying issues early, thus reducing the cost and effort required for fixing bugs at later stages.

Example:

// No direct C# code example for CI system importance. This response is more about processes and practices in CI rather than specific code examples.