.NET Microservices Documentation

Introduction

Testing is a critical part of building reliable microservices. This tutorial walks you through unit, integration, and contract testing strategies using .NET 8.

Prerequisites

• .NET 8 SDK
• Visual Studio 2022 or VS Code
• Docker (optional for external services)
• Basic knowledge of microservice architecture

Setup Test Project

Create a dedicated test project for each service.

dotnet new sln -n MyMicroservice
dotnet new webapi -n OrdersService
dotnet new xunit -n OrdersService.Tests
dotnet sln add OrdersService/OrdersService.csproj
dotnet sln add OrdersService.Tests/OrdersService.Tests.csproj
dotnet add OrdersService.Tests/OrdersService.Tests.csproj reference ../OrdersService/OrdersService.csproj

Unit Testing with xUnit

Focus on business logic isolated from infrastructure.

public class OrderServiceTests
{
    [Fact]
    public void CreateOrder_ShouldReturnValidOrder()
    {
        var repo = new Mock();
        var service = new OrderService(repo.Object);
        var result = service.CreateOrder(new OrderDto { ProductId = 1, Quantity = 2 });
        Assert.NotNull(result);
        Assert.Equal(2, result.Quantity);
    }
}

Integration Testing

Leverage Microsoft.AspNetCore.Mvc.Testing to host the API in-memory.

public class OrdersApiTests : IClassFixture
{
    private readonly HttpClient _client;
    public OrdersApiTests(WebApplicationFactory<Program> factory)
    {
        _client = factory.CreateClient();
    }

    [Fact]
    public async Task GetOrders_ReturnsOk()
    {
        var response = await _client.GetAsync("/api/orders");
        response.EnsureSuccessStatusCode();
        var json = await response.Content.ReadAsStringAsync();
        Assert.Contains("orders", json);
    }
}

Contract Testing

Use Pact to verify provider contracts.

// Provider test (Orders Service)
[Test]
public async Task EnsureProviderMeetsPact()
{
    var pactVerifier = new PactVerifier();
    await pactVerifier
        .ServiceProvider("OrdersService", "http://localhost:5000")
        .HonoursPactWith("OrderConsumer")
        .PactUri("pacts/orderconsumer-ordersservice.json")
        .VerifyAsync();
}

CI/CD Integration

Example GitHub Actions workflow snippet:

name: Build and Test
on:
  push:
    branches: [ main ]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Setup .NET
        uses: actions/setup-dotnet@v3
        with:
          dotnet-version: '8.0.x'
      - name: Restore
        run: dotnet restore
      - name: Build
        run: dotnet build --no-restore
      - name: Test
        run: dotnet test --no-build --verbosity normal

Summary

By combining unit, integration, and contract tests, you can achieve high confidence in your microservices. Integrate these tests into your CI pipeline to catch regressions early.