TDD Series: Mastering Test Driven Development in .NET 7: Real-World Examples and Techniques

Test Driven Development (TDD) is a software development approach that involves writing tests before writing the actual code. The primary aim of TDD is to identify the problems and bugs in the early stages of software development, which makes the development process smoother, more efficient, and less time-consuming. In this article, we will explore TDD with real-world examples in .Net 7.

Writing a Test Case in .Net 7

Before writing the code, it is essential to understand the requirements of the project. Based on the requirements, you can write the test cases in .Net 7 using tools like NUnit, XUnit, and MSTest. These tools provide you with the necessary framework to write test cases for your application. Once you have written the test cases, it is time to implement the actual code.

Examples

String Reversal

Consider a simple example of writing a string reversal function. First, we write the test case that checks whether the string is reversed correctly. Then, we write the implementation that makes the test case pass.

using Xunit;
namespace StringReversalTDD;
public class StringReversalTests
{
    [Fact]
    public void TestStringReversal()
    {
        var sut = new StringReversal();
        var result = sut.Reverse("hello");
        Assert.Equal("olleh", result);
    }
}

public class StringReversal
{
    public string Reverse(string input)
    {
        var charArray = input.ToCharArray();
        Array.Reverse(charArray);
        return new string(charArray);
    }
}

In this example, we start by writing the test case for the string reversal function. The test case uses the Xunit testing framework and the Fact attribute to mark the test method. The test case creates an instance of the StringReversal class and calls the Reverse method with the input "hello". The test case then asserts that the output of the Reverse method is equal to "olleh".

Once the test case is written, we implement the StringReversal class. The implementation is straightforward and involves converting the input string to a character array, reversing the character array, and returning the reversed string.

Bank Account

Consider another example of writing a class for a bank account. The bank account class should allow for depositing and withdrawing money and keep track of the balance.

using Xunit

namespace BankAccountTDD;

public class BankAccountTests
{
    [Fact]
    public void TestDeposit()
    {
        var sut = new BankAccount();
        sut.Deposit(100);
        Assert.Equal(100, sut.Balance);
    }
    [Fact]
    public void TestWithdraw()
    {
        var sut = new BankAccount();
        sut.Deposit(100);
        sut.Withdraw(50);
        Assert.Equal(50, sut.Balance);
    }
}

public class BankAccount
{
    public int Balance { get; private set; }
    public void Deposit(int amount)
    {
        Balance += amount;
    }


    public void Withdraw(int amount)
    {
        Balance -= amount;
    }
}

In this example, we write two test cases for the BankAccount class. The first test case checks whether depositing money into the bank account increases the balance. The second test case checks whether withdrawing money from the bank account decreases the balance.

Conclusion

Test Driven Development (TDD) is an important practice in software development, especially in .NET 7. It enables developers to write reliable, high-quality code that meets requirements and is less prone to bugs and errors. TDD emphasizes writing tests first, before writing the actual implementation code. This approach helps developers to identify and fix problems early in the development cycle, leading to more efficient and effective software development.

In this article, we discussed the benefits of TDD, including improved code quality, increased confidence in code, and reduced development time. We also covered how to write test cases in .NET 7, including the use of testing frameworks and tools, as well as writing test-driven code. Finally, we explored real-world examples of TDD in .NET 7 to illustrate the practical applications of TDD in software development.

Overall, TDD is an essential part of software development that helps developers create high-quality, reliable code, and improve their coding skills. By following these best practices, .NET 7 developers can take their coding to the next level and deliver better results.