🧪 Implement Unit Tests

Name: implement_tests
Rating: 92
Author: lucasbarbosa

Generates unit tests that comply with the DemoApi testing standards.

🎯 Scope

Use this skill when:

•Creating tests for a new Service or Controller.
•Adding coverage for existing legacy code.
•The USER asks to "add tests".

📋 Standards & Conventions

1. Files & Organization

•Project: [ProjectName].Tests (e.g., DemoApi.Application.Tests).
•Granularity: One file per Process/Method being tested (e.g., CreateProductTests.cs instead of ProductServiceTests.cs).
•Base Class: Inherit from common base for setup (e.g., ProductTests which setups the Mocks).

2. Naming Convention

•Format: [MethodName]_Should[ExpectedResult]_When[Scenario]
•Example: Create_ShouldReturnProduct_WhenRepositoryCreatesSuccessfully

3. Tools Breakdown

•Framework: xUnit ([Fact]).
•Mocking: Moq (Mock<IInterface>).
•Assertions: FluentAssertions (result.Should().Be(...)).
•Data Generation: Builders pattern (e.g., ProductBuilder.New().Build()).

🧱 Implementation Template

csharp

using FluentAssertions;
using Moq;
using Xunit;

namespace DemoApi.Application.Tests.Products;

public class CreateProductTests : ProductTests // Inherit shared setup
{
    [Fact]
    public async Task Create_ShouldReturnProduct_WhenRepositoryCreatesSuccessfully()
    {
        // 1. Arrange
        var (notificator, repository, service) = SetProductAppService();
        var fakeEntity = ProductBuilder.New().Build();
        var viewModel = _mapper.Map<ProductViewModel>(fakeEntity);

        repository.Setup(x => x.GetByName(viewModel.Name!))
                  .ReturnsAsync((Product?)null); // Setup specific scenario

        repository.Setup(x => x.Create(It.IsAny<Product>()))
                  .ReturnsAsync(fakeEntity);

        // 2. Act
        var result = await service.Create(viewModel);

        // 3. Assert
        result.Should().NotBeNull();
        result.Name.Should().Be(fakeEntity.Name);

        // Verify Mocks
        repository.Verify(x => x.Create(It.IsAny<Product>()), Times.Once);
        notificator.Verify(x => x.AddError(It.IsAny<string>()), Times.Never);
    }

    [Fact]
    public async Task Create_ShouldReturnNull_WhenValidationFails()
    {
        // Arrange
        var (notificator, repository, service) = SetProductAppService();
        
        // ... Setup failure scenario ...

        // Act
        var result = await service.Create(invalidViewModel);

        // Assert
        result.Should().BeNull();
        notificator.Verify(x => x.AddError(It.IsAny<string>()), Times.Once);
    }
}

🚨 Critical Checkpoints

•Never mock objects you are testing (the System Under Test).
•Always verify INotificatorHandler calls for failure scenarios.
•Use Builders (ProductBuilder) instead of manual object instantiation where possible.
•No Assert.Equal; use result.Should().Be().