1. Introduction to Software Testing
8. The Art and Science of Creating Effective Test Cases ←
In the realm of software development, test cases play a crucial role in ensuring the quality and reliability of software applications. Creating effective test cases requires a deep understanding of both the software being tested and the principles of test design. This article explores the art and science of creating test cases that are thorough, reusable, and easy to understand. We will cover the key elements of test cases, best practices for their creation, and offer links to additional resources for further learning.
Understanding Test Cases
A test case is a documented set of conditions, inputs, and expected results used to determine whether a particular feature of an application is working correctly. Test cases are essential for identifying defects, verifying functionality, and ensuring that the software meets its requirements.
The Objective of Writing Test Cases in Software Testing
- To validate specific features and functions of the software.
- To guide testers through their day-to-day hands-on activity.
- To record a catalog of steps undertaken, which can be revisited in the event of a bug popping up.
- To provide a blueprint for future projects and testers so they don’t have to start work from scratch.
- To help detect usability issues and design gaps early on.
- To help new testers and devs quickly pick up testing, even if they join in the middle of an ongoing project (How to write Test Cases in Software Testing? (with Format & Example)
Writing good test cases is critical for a thorough and optimized software testing process. Testing teams use test cases to:
- Plan what needs to be tested and how to test it before starting testing
- Make testing more efficient by providing important details like preconditions that need to be satisfied before beginning testing and sample data to use during testing
- Measure and track test coverage
- Compare expected results with actual test outcomes to determine if the software is working as intended
- Record how your team has tested your product in the past to catch any regressions/defects or to confirm that new software updates have not introduced any unexpected issues.
Here are four common elements to consider when writing test cases:
- Identify the feature to be tested
- What features of your software require testing? For example, if you want to test your website’s search functionality, you need to mark its search feature for testing.
- Identify the test scenarios
- What scenarios can be tested to verify all aspects of the feature? Examples of potential test scenarios for testing your website’s login feature include:
- What scenarios can be tested to verify all aspects of the feature? Examples of potential test scenarios for testing your website’s login feature include:
- Testing with valid or invalid credentials
- Testing with a locked account
- Testing with expired credentials
It’s important to identify expected results for both positive and negative test scenarios. For example, for a login test scenario with valid credentials, the expected result would be a successful login and redirection to the user’s account page. The expected result for a test scenario with invalid credentials would be an error message and prevention of access to the account page.
- Identify test data
What data will you use to execute and evaluate the test for each test scenario? For example, in a login test scenario for testing with invalid credentials, the test data might include an incorrect username and password combination.
- Identify the test approach
Once you have identified the test feature, scenarios, and data for your test case, you will better understand how to approach the test for the most effective outcomes.
Here are some important considerations for this step:
- If you are testing a new feature for the first time and need to confirm specific functionality, you may want to write more detailed test steps. For example, suppose you are testing a new checkout process for an e-commerce website. In that case, you might include detailed steps such as adding items to the cart, entering shipping and billing information, and confirming the order.
- If your test case design is exploratory or user-acceptance focused, you may simply write a test charter or mission that you would like to accomplish during testing. For example, if you are conducting user acceptance testing for a new feature on a mobile app, your mission might be to ensure that the feature’s login process is easy to use and meets the user’s needs (How to Write Effective Test Cases (With Templates)
Key Elements of a Test Case
Test Case ID: The unique identifier of the test case helps track it more efficiently during testing. It is often used to organize the indexing and searching of tests in test case managers. Such IDs are created automatically in the Test Management System.
Title: A brief description of the test case. Descriptive name of the test case, which conveys its essence and the functionality being tested. A well-chosen name helps to understand the content of the test case quickly.
Preconditions: Conditions that must be met before the test can be executed. Located in the Preconditions section, these conditions define the system's initial state before running the test. They indicate the system's state where the test can be correctly performed.
Test Steps: Detailed instructions on how to execute the test. This section contains a sequence of actions the tester must perform to execute a specific test scenario. Each step should be clearly described and easy to understand.
Test Data: The specific data (like login and password) needed for passing the current test case. It also may be specified in Preconditions or exact Steps. But to keep the test data separate – it's good practice. Not every step of a Test Case needs Test Data.
Expected Results: The expected outcome if the software functions correctly.
Postconditions: Conditions that should be verified after the test execution.
Actual Results: The outcome observed after executing the test.
Status: The pass/fail status of the test case.
Comments: Additional notes or observations from the tester.
Postconditions and Precondition are not mandatory parts. This is most likely a rule of good manners: "Before the test – set up your system, and If you've messed up – clean it up after yourself." This is especially relevant for automated testing when one run fills the database with hundreds or thousands of incorrect documents (HOW TO WRITE TEST CASES FOR SOFTWARE TESTING: A COMPLETE GUIDE)
Example Test Case
Test Case ID: TC001
Title: Verify user login with valid credentials.
Preconditions: User must have a valid account and be logged out.
Test Steps:
- Navigate to the login page.
- Enter the username "testuser" in the username field.
- Enter the password "Password123" in the password field.
- Click the "Login" button.
- Test Data:
- Username: testuser
- Password: Password123
Expected Results:
User should be redirected to the dashboard with a welcome message.
Postconditions:
Verify that the user is logged in and the dashboard displays correctly.
Actual Results:
To be filled after execution.
Status:
To be filled after execution.
Comments:
Verify that no error messages are displayed during login.
Best Practices for Crafting Effective Test Cases
1.Clarity and Precision
- Ensure that each test case is clear and concise to avoid ambiguities.
- Use straightforward language and avoid unnecessary technical jargon.
2. Comprehensive Coverage
- Cover all possible scenarios, including edge cases and boundary conditions.
- Create both positive and negative test cases to ensure robustness.
3. Reusability
- Design test cases to be reusable across different projects or test cycles.
- Avoid hardcoding values that may change frequently.
4. Maintainability
- Keep test cases well-documented and organized for easy updates.
- Regularly review and update test cases to reflect changes in the application.
5. Prioritization
- Focus on critical functionalities and high-risk areas first.
- Use risk-based testing techniques to determine the priority of test cases.
6. Automation-Friendly
- Write test cases with automation in mind to facilitate easier scripting.
- Identify test cases suitable for automation to save time and resources.
7. Peer Review
- Have test cases reviewed by peers to catch potential issues and ensure thoroughness.
- Incorporate feedback to improve the quality of the test cases.
Negative Test Cases
Negative test cases are an essential part of software testing. They focus on ensuring that the application gracefully handles invalid input or unexpected user behavior. The goal is to verify that the system can maintain stability and security, even when faced with erroneous or malicious inputs. This article delves into the concept of negative test cases, provides examples, and offers best practices for crafting effective negative tests.
What Are Negative Test Cases?
Negative test cases are designed to test the software application with invalid, incorrect, or unexpected inputs. These tests help identify vulnerabilities and potential failure points by ensuring that the application can handle error conditions properly without crashing or producing incorrect results.
Key Objectives of Negative Testing
Identify Weaknesses: Detect how the system behaves under adverse conditions.
Enhance Security: Ensure the application is secure against invalid inputs, which could be exploited by attackers.
Improve Robustness: Verify that the application can handle unexpected scenarios gracefully.
Validate Error Handling: Ensure that appropriate error messages are displayed and logged correctly
Examples of Negative Test Case
User Authentication
Test Case ID: TC002
Title: Verify login with invalid credentials.
Preconditions: User must have an account but be logged out.
Test Steps:
Navigate to the login page.
Enter an incorrect username "invalidUser".
Enter an incorrect password "InvalidPass".
Click the "Login" button.
Test Data:
Username: invalidUser
Password: InvalidPass
Expected Results:
The user should not be logged in.
An error message should be displayed, stating "Invalid username or password."
2. Form Validation
Test Case ID: TC003
Title: Verify form submission with empty required fields.
Preconditions: Access the form page.
Test Steps:
Navigate to the form page.
Leave all required fields empty.
Click the "Submit" button.
Expected Results:
The form should not be submitted.
An error message should be displayed for each empty required field, indicating that the fields must be filled.
3. File Upload
Test Case ID: TC004
Title: Verify file upload with unsupported file type.
Preconditions: Access the file upload section.
Test Steps:
Navigate to the file upload section.
Select a file with an unsupported file type (e.g., .exe).
Attempt to upload the file.
Expected Results:
The file should not be uploaded.
An error message should be displayed, indicating that the file type is not supported.
4. Input Field Limits
Test Case ID: TC005
Title: Verify input field with input exceeding maximum length.
Preconditions: Access the input field form.
Test Steps:
Navigate to the input field form.
Enter a string that exceeds the maximum allowed length (e.g., 256 characters).
Attempt to submit the form.
Expected Results:
The form should not be submitted.
An error message should be displayed, stating that the input exceeds the maximum length allowed.
5. SQL Injection
Test Case ID: TC006
Title: Verify input fields against SQL injection attempts.
Preconditions: Access a form with input fields.
Test Steps:
Navigate to the input field form.
Enter an SQL injection string (e.g., "' OR '1'='1").
Attempt to submit the form.
Expected Results:
The form should not be submitted.
An error message should be displayed.
The system should handle the input securely without executing any SQL commands.
Best Practices for Crafting Negative Test Cases
1. Understand the Application
- Know the expected behavior of the application under various conditions.
- Understand the constraints and limitations of the input fields and overall system.
2. Define Clear Objectives
- Clearly define what you aim to achieve with each negative test case
- Focus on areas that are most likely to fail or be exploited.
3. Use Diverse Input
- Test with a wide range of invalid inputs, including special characters, excessively long strings, and incorrect data formats.
- Consider edge cases and boundary values.
4. Automate Where Possible
- Automate repetitive negative test cases to save time and ensure consistency.
- Use automation tools that support negative testing.
5. Validate Error Handling
- Ensure that error messages are clear, user-friendly, and do not reveal sensitive information.
- Check that errors are logged appropriately for debugging purposes.
6. Review and Update
- Regularly review and update negative test cases to reflect changes in the application.
- Incorporate feedback from developers and other testers to improve test coverage (Everything You Need to Know About Negative Test Cases)
You can also familiarize yourself with the creation of test cases in the document Azure Test Plans documentation.
Conclusion
Crafting effective test cases is a critical skill in software testing, blending the art of clear and comprehensive documentation with the science of meticulous test design. By following best practices and continuously refining your approach, you can create test cases that ensure the reliability and quality of your software.
Remember, thorough testing is the foundation of successful software development, and well-crafted test cases are the tools that make it possible.
Negative test cases are a crucial part of a comprehensive testing strategy. By anticipating and testing for invalid inputs and unexpected user behaviors, you can ensure that your software is robust, secure, and user-friendly. Following best practices and regularly updating your test cases will help maintain high-quality standards and improve overall software reliability.
Useful links:
Top 8 free test case management software: peculiarities, features, and integrations
Test Management Tool. Planning, execution, management, and reporting
Make Your Test Case Writing More Efficient
How to write Test Cases – Software Testing
How to Write Test Cases with Examples
How to Write Functional Test Cases for Thorough Coverage