A Complete Guide to Writing Effective Test Cases for Software Testing

The software functions correctly, meets requirements, and is user-friendly. Effective test cases not only verify functionality but also improve software quality by catching bugs early. Writing effective test cases is both an art and a science, requiring a structured approach, clear communication, and an understanding of the user’s perspective.

In this blog, we will dive deep into what constitutes an effective test case and how to create them with real-time scenarios to highlight key aspects.

Test cases define how to test a system, software, or application. A test case is a singular set of actions or instructions for a tester to perform that validates a specific aspect of a product or application functionality. If the test fails, the result might be a software defect that the organization can triage.

What is a Test Case?

A test case is a set of actions, conditions, and inputs developed to test a particular functionality or feature of an application. It outlines how to test the software and includes the steps, the expected outcomes, and the actual results.

Components of a Test Case

1. Test Case ID: A unique identifier for each test case.
2. Test Case Title: A brief description of what is being tested.
3. Test Case Title: A brief description of what is being tested.
4. Test Data: The specific data inputs that will be used during the test.
5. Steps to Execute: A detailed, step-by-step guide on how to execute the test case.
6. Expected Results: What should happen if the application works as intended?
7. Actual Results: What happens when the test case is executed?
8. Postconditions: Any actions that need to be done after the test execution (e.g., data cleanup).
9. Priority: The importance or urgency of the test case.
10. Test Environment: The specific software and hardware environment in which the test case should be executed.

Characteristics of Effective Test Cases

Creating effective test cases is crucial for ensuring the quality and reliability of software. Here are the key characteristics of effective test cases in detail:

1. Clear and Concise
   🔺Description: Each test case should have a clear purpose and be easy to understand. Avoid jargon and ensure that anyone reading it can grasp the intent without confusion.
   🔺Example: Instead of saying “check if the button works,” specify “verify that clicking the ‘Submit’ button triggers the form submission.”
   
2. Specific and Precise
   🔺Description: Effective test cases should focus on specific functionalities, avoiding ambiguity. Each test case should test a single aspect of the application.
   🔺Example: A test case for logging in should cover only the login functionality, not touch on password reset or account creation.
   
3. Well-Structured
   🔺Description: Use a standardized format for test cases to enhance readability and maintainability. Typically includes sections like Test Case ID, Description, Pre-conditions, Test Steps, Expected Results, and Post-conditions.
   
4. Traceable
   🔺Description: Each test case should be traceable back to a specific requirement or user story. This ensures that all requirements are being tested and helps in tracking coverage.
   🔺Example: Link each test case to a corresponding requirement ID in your documentation.
   
5. Reproducible
   🔺Description: Test cases should be written in such a way that they can be executed multiple times with the same results.  This includes clear steps and the same environment setup.
   🔺Example: If a test case involves database states, specify the exact state required before execution.
   
6. Independent
   🔺Description: Each test case should stand alone without dependencies on other test cases. This allows for easier execution in any order.
   🔺Example: Avoid writing test cases that depend on the outcomes of previous tests.
   
7. Comprehensive
   🔺Description: A set of test cases should cover all possible scenarios, including positive, negative, edge cases, and boundary conditions.
   🔺Example: For a login test case, include scenarios for valid credentials, invalid credentials, empty fields, and special characters.
   
8. Automatable
   🔺Description: Where possible, test cases should be designed with automation in mind. This means they should be simple enough to be converted into automated tests without losing clarity.
   🔺Example: Use clear input values and expected outcomes that can be easily scripted.
   
9. Prioritized
   🔺Description: Test cases should be prioritized based on risk and impact. This ensures that critical functionalities are tested first.
   🔺Example: Use a rating system (e.g., High, Medium, Low) to categorize test cases based on their importance to the application.
   
10. Maintainable
    🔺Description: Test cases should be easy to update as requirements change. This involves keeping them organized and minimizing hard-coded values.
    🔺Example: Use parameters for input values rather than hard-coded data wherever possible.
    
11. Defect Reporting
    🔺Description: An effective test case should help identify defects. Include sections for actual results and any observed issues to facilitate bug tracking.
    🔺Example: Include fields for capturing screenshots or error messages encountered during execution.
    
12. Execution-ready
    🔺Description: Test cases should be ready to execute, with all necessary information available. This includes required setup steps, input data, and environment configurations.
    🔺Example: Specify which user roles are needed for execution, or if specific software versions are required.

Related read: Step By Step Software Testing Process To Achieve Top Product Quality

Types of Test Cases

1. Positive Test Cases: These test the system’s expected behavior when valid inputs are provided.
   Example: In a login form, a positive test case would be entering a valid username and password combination and checking if the user is redirected to the home page.
2. Negative Test Cases: These test the system’s behavior when invalid inputs are provided.
   Example: For a phone number field, entering non-numeric characters or leaving the field blank would be negative test cases to check if appropriate error messages appear.
3. Boundary Test Cases: These test the edge limits of input fields.
   Example: If the username field in a signup form allows a minimum of 6 characters and a maximum of 20 characters, create test cases for 5, 6, 20, and 21 characters to ensure the field behaves correctly at its boundaries.
4. Performance Test Cases: These test the system’s performance under specific conditions like load, stress, or endurance.
   Example: In a gym training app, testing how the application performs when 1000 users simultaneously purchase workout sessions would be a performance test case.
5. Usability Test Cases: These ensure the software is user-friendly and meets UI/UX standards.
   Example: In an app where users can search for places, usability test cases would ensure that the search results are displayed in a readable format, and the search bar is easily accessible.
6. Security Test Cases: These test how well the application protects sensitive data and resists unauthorized access.
   Example: Test cases for validating that sensitive data like passwords are encrypted and not visible in plain text during transmission over the network.

Real-Time Scenarios

🔹Scenario 1: Log in with Google on the Mobile App
In a mobile application, users can sign in using their Google accounts.

• Test Case:
  🔺Title: Verify Google login functionality.
  🔺Precondition: The user has a valid Google account and is logged into Google on their phone.
  🔺Steps:
  1.   Open the app and navigate to the login screen.
  2.  Click the “Login with Google” button.
  3.  Select the Google account.
  🔺Expected Result: The user should be logged in successfully and redirected to the app’s home page.

🔹Scenario 2: Phone Number Signup with OTP
Users sign up for a mobile app by entering their phone number and verifying it with an OTP.

• Test Case:
  🔺Title: Verify OTP verification for phone number signup.
  🔺Precondition: The app is installed, and the user is on the signup screen.
  🔺Steps:
  1. Enter a valid phone number.
  2. Click “Send OTP.”
  3. Enter the received OTP.
  🔺Expected Result: The user is signed up successfully and taken to the profile setup page.
  🔺Negative Test Case:
  1. Enter an invalid phone number.
  2. Click “Send OTP.”
  🔺Expected Result: The app should show an error message, “Invalid phone number. Please try again.”

🔹Scenario 3: Search Functionality Based on User Location
Users can search for nearby places based on their current location in a mobile app.

• Test Case:
  🔺Title: Verify search functionality based on the user’s current location.
  🔺Precondition: The user has granted location permissions to the app.
  🔺Steps:
  1. Open the app and navigate to the search screen.
  2. Tap the “Search near me” button.
  3. Enter the search term, e.g., “Gym.”
  🔺Expected Result: The app displays a list of gyms near the user’s location.

Best Practices for Writing Test Cases

1. Understand the Requirement: Before writing a test case, thoroughly understand the requirement or feature being tested. Collaborate with business analysts, developers, and stakeholders to clarify any doubts.
2. Use Clear and Actionable Language: When describing the steps and expected outcomes, use concise and precise language. Avoid vague terms like “maybe” or “possibly.”
3. Ensure Test Coverage: Ensure your test cases cover all functional and non-functional requirements, including edge cases and potential error conditions.
4. Automate Where Possible: Repetitive test cases, like regression tests, can be automated. Use frameworks like TestNG, JUnit, or Selenium to automate such tests for increased efficiency.
5. Review and Update Test Cases: Regularly review test cases to ensure they are relevant to the current version of the software. Update them whenever new features are introduced or old features are modified.