Added smtp server instance in functional tests using test-containers

sample/Directory.Packages.props

@@ -34,6 +34,7 @@
     <PackageVersion Include="SQLite" Version="3.13.0" />
     <PackageVersion Include="Swashbuckle.AspNetCore" Version="6.5.0" />
     <PackageVersion Include="Swashbuckle.AspNetCore.Annotations" Version="6.5.0" />
+    <PackageVersion Include="Testcontainers" Version="3.9.0" />
     <PackageVersion Include="xunit" Version="2.9.1" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.2" />
   </ItemGroup>

sample/tests/NimblePros.SampleToDo.FunctionalTests/Fixtures/SmtpServerFixture.cs

@@ -0,0 +1,62 @@
+using DotNet.Testcontainers.Builders;
+using DotNet.Testcontainers.Containers;
+using Xunit;
+
+namespace NimblePros.SampleToDo.FunctionalTests.ClassFixtures;
+
+/// <summary>
+/// This class ensures that an SMTP server is running and shared between all tests in a specified class.
+/// </summary>
+public class SmtpServerFixture : IAsyncLifetime
+{
+  private const string SmtpServerImageName = "jijiechen/papercut:latest";
+  private const int SmtpServerListenPort = 25;
+
+  private IContainer? _container;
+
+  public async Task InitializeAsync()
+  {
+    _container = new ContainerBuilder()
+        .WithName(Guid.NewGuid().ToString("D"))
+        .WithImage(SmtpServerImageName)
+        .WithPortBinding(SmtpServerListenPort, SmtpServerListenPort)
+        .WithWaitStrategy(
+          Wait
+          .ForUnixContainer()
+          .UntilMessageIsLogged("Server Ready", o => o.WithTimeout(TimeSpan.FromSeconds(30))))
+        .Build();
+
+    await _container.StartAsync().ConfigureAwait(false);
+  }
+
+  public async Task DisposeAsync()
+  {
+    if (_container != null)
+    {
+      await _container.StopAsync().ConfigureAwait(false);
+      await _container.DisposeAsync().ConfigureAwait(false);
+      _container = null;
+    }
+  }
+
+  /// <summary>
+  /// Ensures that the container is running and healthy.
+  /// </summary>
+  /// <exception cref="InvalidOperationException">
+  /// Thrown when the SMTP server container was not created or is not running.
+  /// This could be due to Docker not running or issues with the container image.
+  /// In such cases, verify that Docker is running correctly.
+  /// </exception>
+  public void EnsureContainerIsRunning()
+  {
+    if (_container == null)
+    {
+      throw new InvalidOperationException("SMTP server container was not created. Ensure Docker is running and the container image is correct.");
+    }
+
+    if (_container.State != TestcontainersStates.Running)
+    {
+      throw new InvalidOperationException("The SMTP server container is not running. Please verify that the SMTP server image is correctly configured and that Docker is functioning properly.");
+    }
+  }
+}

sample/tests/NimblePros.SampleToDo.FunctionalTests/NimblePros.SampleToDo.FunctionalTests.csproj

@@ -9,6 +9,7 @@
   <ItemGroup>
     <PackageReference Include="FluentAssertions" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="Testcontainers" />
     <PackageReference Include="xunit" />
     <PackageReference Include="xunit.runner.visualstudio">
       <PrivateAssets>all</PrivateAssets>

sample/tests/NimblePros.SampleToDo.FunctionalTests/Projects/ProjectItemMarkComplete.cs

@@ -6,17 +6,21 @@
 using NimblePros.SampleToDo.Web.Endpoints.Projects;
 using NimblePros.SampleToDo.Web.Projects;
 using FluentAssertions;
+using NimblePros.SampleToDo.FunctionalTests.ClassFixtures;
 
 namespace NimblePros.SampleToDo.FunctionalTests.Projects;
 
 [Collection("Sequential")]
-public class ProjectItemMarkComplete : IClassFixture<CustomWebApplicationFactory<Program>>
+public class ProjectItemMarkComplete : 
+  IClassFixture<CustomWebApplicationFactory<Program>>,
+  IClassFixture<SmtpServerFixture>
 {
   private readonly HttpClient _client;
 
-  public ProjectItemMarkComplete(CustomWebApplicationFactory<Program> factory)
+  public ProjectItemMarkComplete(CustomWebApplicationFactory<Program> factory, SmtpServerFixture smtpServer)
   {
     _client = factory.CreateClient();
+    smtpServer.EnsureContainerIsRunning();
   }
 
   [Fact]