[Enhancement]: Refactor Testcontainers.Xunit module

[digital88]

Problem

As per PR the default parameterless Builder constuctor is deprecated. This line in Testcontainers.Xunit module should be refactored to create instances of Builders using new constructor.

See alse comment.

Solution

• Use factory or delegate to create builders
• Use InternalsVisibleTo attribute and make default constructor internal instead of deleting it later
• Use reflection to create builders
• Something else

Benefit

The working Testcontainers.Xunit module without calling deprecated constructors.

Alternatives

Keep deprecated constructors for some time.

Would you like to help contributing this enhancement?

Yes

[HofmeisterAn]

@0xced FYI: Testcontainers for .NET (like the other language implementations) expects developers to configure and pin the image in future releases (no more default image: #1470).

[0xced]

Thanks for the heads up, Andre. I'll share some thoughts about how we can transition the Testcontainers.Xunit modules to this new approach, hopefully by the end of 2025. Please ping me in 2026 if I don't get around.

[HofmeisterAn]

I've had a quick look at this, and the cleanest approach is probably something like this and moving the builder creation down to the fixture. LMKWYT.

diff --git a/src/Testcontainers.Xunit/ContainerLifetime.cs b/src/Testcontainers.Xunit/ContainerLifetime.cs
index dffaf57a..3d8e4c31 100644
--- a/src/Testcontainers.Xunit/ContainerLifetime.cs
+++ b/src/Testcontainers.Xunit/ContainerLifetime.cs
@@ -6,7 +6,7 @@ namespace Testcontainers.Xunit;
 /// <typeparam name="TBuilderEntity">The builder entity.</typeparam>
 /// <typeparam name="TContainerEntity">The container entity.</typeparam>
 public abstract class ContainerLifetime<TBuilderEntity, TContainerEntity> : IAsyncLifetime
-    where TBuilderEntity : IContainerBuilder<TBuilderEntity, TContainerEntity, IContainerConfiguration>, new()
+    where TBuilderEntity : IContainerBuilder<TBuilderEntity, TContainerEntity, IContainerConfiguration>
     where TContainerEntity : IContainer
 {
     private readonly Lazy<TContainerEntity> _container;
@@ -16,9 +16,15 @@ public abstract class ContainerLifetime<TBuilderEntity, TContainerEntity> : IAsy
 
     protected ContainerLifetime(ILogger logger)
     {
-        _container = new Lazy<TContainerEntity>(() => Configure(new TBuilderEntity().WithLogger(logger)).Build());
+        _container = new Lazy<TContainerEntity>(() => Configure(CreateBuilder().WithLogger(logger)).Build());
     }
 
+    /// <summary>
+    /// Creates the container builder instance.
+    /// </summary>
+    /// <returns>An instance of <typeparamref name="TBuilderEntity" />.</returns>
+    protected abstract TBuilderEntity CreateBuilder();
+
     /// <summary>
     /// Gets the container instance.
     /// </summary>