Symptom

Flaky CI failure (ubuntu leg, run 27100880280, PR #6178 — unrelated changes):

Error executing After hooks for TUnit.TestProject.DynamicTests.Runtime(...).SomeMethod(...):
TUnit.Core.Exceptions.AfterClassException: AfterEveryClass hook failed: Object reference not set to an instance of an object.
 ---> System.NullReferenceException
   at TUnit.TestProject.AfterTests.AfterEveryClassHooks.AfterEveryClass(ClassHookContext context)

The hook dereferences test.Metadata.TestDetails.TestName while iterating context.Tests (TUnit.TestProject/AfterTests/AfterEveryClassTests.cs:10).

Root cause

1. ContextProvider.CreateTestContext (TUnit.Core/ContextProvider.cs:94) calls classContext.AddTest(testContext) immediately after constructing the TestContext.
2. TestDetails is null!-initialized (TUnit.Core/TestContext.cs:310) and only assigned later by the builder (TUnit.Engine/Building/TestBuilder.cs:1086, TestBuilderPipeline.cs:274/401/481/536).
3. So there is a window where a partially-built TestContext (with TestDetails == null) is observable via ClassHookContext.Tests.

For statically discovered tests this window closes before any hooks run. For dynamic tests (AddDynamicTest) it doesn't: DynamicTests.Runtime.BuildTests registers multiple dynamic tests at runtime into the same ClassHookContext (keyed by Type). When one dynamic test finishes and triggers AfterEvery(Class) while a sibling dynamic test's context is mid-construction, the hook observes TestDetails == null → NRE.

Possible fixes

• Assign TestDetails before the context becomes visible (e.g. pass into the TestContext ctor or set before AddTest), or
• Defer classContext.AddTest(...) until the test is fully built, or
• Have ClassHookContext.Tests filter out contexts whose TestDetails is not yet set.

First option seems most robust — it removes the partially-initialized published state rather than masking it.

Applies to both reflection and source-gen modes (shared ContextProvider/builder path).