TraceId and similar should be a fixed value when Testing with WebApplicationFactory

[snebjorn]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When using builder.Services.AddProblemDetails(); error output like 400 will have a traceId - which is useful.

{
  "type": "https://tools.ietf.org/html/rfc9110#section-15.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "traceId": "00-9a91dea3f49537ea081001f1435df8f6-9a48ee11db3f47a3-00"
}

However when writing tests using WebApplicationFactory the returned traceId is out of my control or at least not straight forward to set to a known value.

Expected Behavior

traceId and similar tracking ids should be fixed or easily configurable when testing via WebApplicationFactory.

Steps To Reproduce

1. Spin up a asp net web api
2. Add builder.Services.AddProblemDetails();
3. Make an endpoint return a bad request
4. Write a test that checks the returned data
5. Notice the traceId change

Exceptions (if any)

No response

.NET Version

9.0.202

Anything else?

The easy workaround is to ignore traceId in the test. But that's not the point.

[martincostello]

I wouldn't support such a change - I want HTTP requests in my tests to have unique trace identifiers so I can correlate them in logs/traces. Everything having the same trace ID would make this impossible. It's also making the system under test behave differently to the code you would run in production, which is something you should aim to keep to a minimum.

HttpContext.TraceIdentifier is settable, so you can inject your own behaviour into the system under test to modify it, such as by using IHttpContextAccessor to access it and set it to a fixed value.

[eskild-th]

I want HTTP requests in my tests to have unique trace identifiers so I can correlate them in logs/traces.

I must admit I turn off logging when running tests 😄
I'd argue that if something changes the outcome of a test it should be set to a known value in the test.

HttpContext.TraceIdentifier is settable

Unfortunately the traceId is set this way

aspnetcore/src/Mvc/Mvc.Core/src/Infrastructure/DefaultProblemDetailsFactory.cs

Line 105 in b96167f

var traceId = Activity.Current?.Id ?? httpContext?.TraceIdentifier;

and Activity.Id is read only

var activityFeature = context.HttpContext.Features.Get<IHttpActivityFeature>();
activityFeature.Activity.Id;

So far I've been unable to set traceId to a known value. Coming back to my request of it being "straight forward to set to a known value".

[martincostello]

I have no issues with changes so you can change it - I'm just against it being the default behaviour.