Bulletproof your .NET Applications: A Comprehensive Guide to NUnit, Moq, and FluentAssertions

Introduction

Testing is a crucial part of software development. It ensures that the code behaves as expected, and bugs are caught before they make it into production. In the .NET Core ecosystem, NUnit is a popular unit testing framework, and Moq and FluentAssertions are widely used testing libraries. In this blog post, we will explore how to use these tools to perform production-level testing in a .NET Core API.

Setting up the Project

Before we can start writing tests, we need to set up a .NET Core API project. We will create a new project using the dotnet CLI:

dotnet new webapi -n MyApi

This command creates a new .NET Core web API project with the name “MyApi”.

Adding Dependencies

Next, we need to add the necessary dependencies for testing. We will use NUnit as our testing framework, NUnit3TestAdapter to run our tests, Moq for mocking dependencies, and FluentAssertions for more readable assertions.

We can add these dependencies to the project using the dotnet CLI:

dotnet add package NUnit
dotnet add package NUnit3TestAdapter
dotnet add package Moq
dotnet add package FluentAssertions

Writing Tests

With the project and dependencies set up, we can now start writing tests. Let’s say we have a simple API that returns a list of products. We can create a test for this API using NUnit:

using System.Collections.Generic;
using System.Threading.Tasks;
using FluentAssertions;
using Moq;
using MyApi.Controllers;
using MyApi.Models;
using NUnit.Framework;

namespace MyApi.Tests
{
    public class ProductsControllerTests
    {
        [Test]
        public async Task Get_ReturnsListOfProducts()
        {
            // Arrange
            var products = new List<Product>
            {
                new Product { Id = 1, Name = "Product 1", Price = 9.99m },
                new Product { Id = 2, Name = "Product 2", Price = 19.99m },
                new Product { Id = 3, Name = "Product 3", Price = 29.99m }
            };

            var mockRepository = new Mock<IProductRepository>();
            mockRepository.Setup(repo => repo.GetProductsAsync())
                .ReturnsAsync(products);

            var controller = new…