Unit Testing (NUnit/xUnit)

Let's complete your Library System project by adding unit tests! Testing is essential for ensuring your code works correctly and continues to work as you make changes. You'll create a dedicated test file that verifies the core functionality of your library system.

You'll continue working with your existing project structure, adding a new test file:

• Book.cs: Keep your Book class with Id, Title, Author, IsAvailable, and the Borrow() and Return() methods.
• User.cs: Keep your User class with borrowing tracking, MaxBooks constant, CanBorrow(), and methods for managing borrowed books.
• Library.cs: Keep your Library class with borrowing logic, search methods, and the GetAllBooks() and GetAllUsers() methods.
• LibraryTests.cs: This is your new test file! Create a test class that verifies your library system works correctly. You'll write test methods that check various scenarios and report whether each test passes or fails.
• Program.cs: Your entry point that runs the tests and displays results.

Your test class should include methods that test these scenarios:

• TestBookBorrow - Verify that borrowing an available book succeeds and changes its availability
• TestBookBorrowUnavailable - Verify that borrowing an already-borrowed book fails appropriately
• TestUserBorrowingLimit - Verify that users cannot borrow more than 3 books
• TestBookReturn - Verify that returning a borrowed book works correctly
• TestSearchByAuthor - Verify that searching by author returns the correct books

Each test method should return a boolean indicating whether the test passed. Create a simple test runner that executes all tests and prints the results.

You will receive the following inputs:

• Number of test scenarios to run (1-5, corresponding to the tests listed above)

For each test that runs, print the result in the format:

{TestName}: {PASS|FAIL}

After all tests complete, print a summary:

--- Test Summary ---
Passed: {count}
Failed: {count}
Total: {count}

For example, if the input is:

3

The output should be:

TestBookBorrow: PASS
TestBookBorrowUnavailable: PASS
TestUserBorrowingLimit: PASS
--- Test Summary ---
Passed: 3
Failed: 0
Total: 3

Another example with all 5 tests:

5

The output should be:

TestBookBorrow: PASS
TestBookBorrowUnavailable: PASS
TestUserBorrowingLimit: PASS
TestBookReturn: PASS
TestSearchByAuthor: PASS
--- Test Summary ---
Passed: 5
Failed: 0
Total: 5

Your tests should create fresh instances of Book, User, and Library for each test to ensure isolation. This way, one test's state doesn't affect another. Think of each test as a self-contained verification of a specific behavior in your system!