Top 50 Unit Test Cases Every Tester and Developer Should Know

The specific values or conditions provided to the unit under test.

The result anticipated when the unit processes the input data.

The result produced by the unit when the test case is executed.

A comparison that checks if the expected output matches the actual output, determining the pass or fail status of the test case.

Unit testing facilitates the identification and resolution of bugs early in the development process, reducing the time and cost associated with debugging later stages.

Writing unit tests encourages developers to create cleaner, more modular code. This practice not only enhances software quality and helps to match QA kpis but also makes it easier to understand and maintain.

A robust suite of unit tests provides developers with the confidence to refactor code without the fear of introducing new bugs. Automated tests can quickly identify any unintended side effects of changes.

Since each unit is tested independently, integrating different components into a complete system becomes more straightforward and less error-prone.

Unit tests serve as a form of documentation for the code. They illustrate how units are intended to be used, providing valuable insights for other developers who may work on the codebase in the future.

Test functions that are designed to operate without any input arguments. This ensures that the function behaves as expected even when no parameters are provided. Such tests are important for verifying default behaviors and internal state handling.

Verify that functions produce the correct output when given valid and expected input values. This is crucial for confirming that the function meets its requirements and produces accurate results in normal use cases.

Test how functions handle invalid or unexpected inputs to ensure that they manage errors gracefully. This includes checking whether the function returns appropriate error messages or handles exceptions without crashing.

Check the function’s behavior with input values at the edges of valid ranges. Boundary value testing helps ensure that the function can handle extreme values correctly, which is vital for robust error handling.

Assess how the function responds to null or empty input. This is important for verifying that the function can handle cases where no meaningful data is provided, ensuring it operates correctly in such scenarios.

Test both branches of conditional statements (if-else) to ensure that each branch is executed and functions as intended. This helps confirm that all possible conditions are handled correctly.

Evaluate loops with different input values, including edge cases like empty loops or potential infinite loops. Proper testing of loops ensures they execute as expected and handle various conditions effectively.

Test all possible cases in switch statements, including the default case. This ensures that the switch statement covers all scenarios and behaves correctly across different inputs.

Verify that the function correctly handles different exception scenarios. This includes testing for various error conditions and ensuring that exceptions are caught and managed properly, preventing the application from crashing.

Test basic arithmetic operations with integer values to ensure correctness. This includes operations such as addition, subtraction, multiplication, and division, which are fundamental to many functions.

Evaluate floating-point arithmetic operations to ensure accuracy, considering potential issues like precision and rounding errors. Proper testing ensures that calculations with decimal values are reliable.

Test various string operations, including concatenation, substring extraction, length calculation, and comparison. String manipulation is a common task, and thorough testing ensures that all string-related functions work correctly.

Check logical operations (AND, OR, NOT) with different boolean value combinations. This helps verify that logical conditions are evaluated and processed correctly.

Evaluate operations on arrays and lists, including creation, manipulation (adding, removing, modifying elements), and access. Proper testing ensures that data structures are handled correctly.

Test object-oriented principles such as object creation, inheritance, polymorphism, and encapsulation. This ensures that object-oriented features are implemented correctly and behave as expected.

Test different method signatures with the same name to ensure the correct method is called based on the provided arguments. Method overloading allows multiple methods with the same name but different parameters, and testing ensures proper functionality.

Verify that overridden methods in subclasses work correctly and respect the base class methods. This ensures that polymorphism is correctly implemented and that subclass methods behave as expected.

Evaluate recursive functions by testing base cases and recursive calls. Proper testing ensures that the function terminates correctly and produces the expected results.

Test functions passed as arguments to other functions to ensure they are invoked correctly and produce the expected outcomes. This is important for verifying that callback functions work as intended.

Verify different return values from functions to ensure they are correct and used appropriately. This includes testing various scenarios to ensure the function returns the expected results.

Ensure that all statements in the code are executed at least once. Statement coverage helps verify that every part of the code is tested.

Test all possible branches of conditional statements to ensure that each branch is executed and functions correctly. Branch coverage helps ensure that all decision points are tested.

Verify that all possible execution paths through the code are tested. Path coverage ensures that all possible sequences of executed statements are evaluated.

Test all functions in the code to ensure that each function is executed and validated. Function coverage ensures that every function is tested for correctness.

Test all possible outcomes of conditions in the code to ensure that each condition is evaluated properly. Condition coverage helps verify that all logical conditions are tested.

Evaluate the performance of code under various load conditions. Performance testing ensures that the code meets performance requirements and can handle stress effectively.

Test for vulnerabilities such as SQL injection, cross-site scripting (XSS), and buffer overflows. Security testing helps ensure that the code is secure against potential threats.

Assess the user interface for ease of use and intuitive navigation. Usability testing ensures a positive user experience and that the application is user-friendly.

Verify the code’s compatibility with different operating systems, browsers, and devices. Compatibility testing ensures that the application performs consistently across various platforms.

Test the code’s ability to handle different languages and cultural contexts. This ensures that the application can be adapted for different regions and languages.

Evaluate interactions with the database, including queries, updates, and transactions. Database testing ensures correctness and performance of database operations.

Test file operations such as reading, writing, and deleting to ensure correct handling and error management. File handling testing verifies that file operations are performed as expected.

Assess network calls and data transfer for reliability and security. Network communication testing ensures that network interactions are reliable and secure.

Test the code for thread safety and synchronization issues. Concurrency testing ensures that the code handles concurrent operations correctly and avoids synchronization problems.

Evaluate how the code handles errors and recovers from unexpected situations. Error handling and recovery testing ensures that the application can manage and recover from errors effectively.

Test input values at the edges of valid ranges to uncover potential errors. Boundary value analysis helps identify issues that may arise at the limits of acceptable input.

Test different input values that are expected to produce equivalent results to identify potential errors. Equivalence partitioning helps ensure that the function behaves correctly across a range of similar inputs.

Use decision tables to test various combinations of input values and expected outputs. This ensures that all possible scenarios are covered and that the function handles each scenario appropriately.

Evaluate how the system behaves under different state transitions. This helps verify that the system correctly handles changes in state and transitions between different states.

Test for common error conditions based on experience and intuition. Error guessing helps identify potential issues that may not be covered by formal testing techniques.

Adopt TDD by writing test cases before implementing code. This approach helps ensure that code meets requirements from the start and promotes better design.

Implement BDD by writing tests based on user stories and business requirements. BDD helps align code with business goals and ensures that functionality meets user needs.

Integrate unit testing into the CI/CD pipeline to automate testing and ensure continuous code quality. CI/CD helps maintain high-quality code through automated testing and deployment.

Use mutation testing to introduce intentional faults into the code and measure the effectiveness of your test cases. Mutation testing helps identify weaknesses in test coverage.

Generate random test data to test code behavior across a wide range of inputs. Property-based testing helps ensure that the code behaves correctly under diverse conditions.

Familiarize yourself with popular unit testing frameworks and libraries like JUnit, NUnit, and Pytest. These tools facilitate effective unit testing and provide essential features for testing.

Explore techniques for efficiently generating test data. Proper test data generation helps ensure that tests cover a broad range of scenarios.

Learn how to prioritize test cases based on risk and impact. Prioritization helps focus on the most critical tests and improves testing efficiency.

Use tools to measure test coverage and identify areas for improvement. Test coverage analysis helps ensure that all important aspects of the code are tested.

Keep test cases up-to-date as the code evolves. Regular maintenance ensures that tests remain relevant and continue to provide value as the codebase changes.