Introduction to Unit Testing

What is Unit Testing?

• A unit test is a piece of code written by a developer to test specific functionality of their code.
• It provides feedback on whether the code functions as expected.
• Functionality is usually encapsulated within a class.
  • Class Under Test: The class being tested.
  • Method Under Test: The specific method within the class that is being tested.
• The unit tests:
  • Instantiate the class under test.
  • Execute the method under test.
  • Verify the outcome to ensure it behaves as expected.

Characteristics of a Good Unit Test

1. Easy to Write

   • Unit tests should be simple to create because they test small pieces of code.
   • Developers need to write multiple tests for different scenarios, making ease of writing crucial.

2. Readability

   • Unit tests should be clear and understandable, showing their intent.
   • Other developers should easily comprehend what is being tested without extensive effort.

3. Reliability

   • Unit tests should not depend on one another or on the environment they run in.
   • Tests should provide consistent results across different machines and environments.

4. Fast Execution

   • Unit tests should run quickly to provide rapid feedback to developers.
   • With potentially hundreds or thousands of tests, fast execution is essential for efficient workflow.

5. Isolation

   • Tests should not rely on external services (like databases or network calls) that can slow down execution.
   • Isolated tests ensure consistent and speedy results.

Conclusion

• Good unit tests are easy to write, readable, reliable, fast, and isolated from external factors.
• These characteristics contribute to effective unit testing practices that support the development process.