fix(aspnetcore): honor WebApplicationFactoryClientOptions in CreateClient

[thomhurst]

Fixes #6921.

Problem

TestWebApplicationFactory<T>.CreateClient() shadows WebApplicationFactory<T>.CreateClient() to add TUnit's propagation handlers, but it never applied ClientOptions:

• No CookieContainerHandler was created, so cookies set by a /login request were not sent on later requests and cookie auth broke.
• No RedirectHandler was created, so AllowAutoRedirect and MaxAutomaticRedirections were ignored.
• ClientOptions.BaseAddress was dropped.

TracedWebApplicationFactory<T>.CreateClient() (the Factory exposed by WebApplicationTest) had the same bug. Also, the base CreateClient(WebApplicationFactoryClientOptions) overload was not shadowed. It honored the options but silently skipped the TUnit tracing and test-ID handlers, because the base CreateDefaultClient is not virtual.

Fix

• New internal TUnitHttpClientFilter.CreateClientOptionsHandlers(options). It returns RedirectHandler and CookieContainerHandler (based on the options) followed by the propagation handlers. This mirrors the internal WebApplicationFactoryClientOptions.CreateHandlers() using the public handler types, so no reflection is needed.
• TestWebApplicationFactory<T>:
  • CreateClient() now delegates to CreateClient(ClientOptions).
  • New new CreateClient(WebApplicationFactoryClientOptions) overload that uses the option handlers and applies BaseAddress.
• TracedWebApplicationFactory<T>: same two methods, using Inner.ClientOptions.

The propagation handlers sit inside RedirectHandler and CookieContainerHandler, so every redirect hop gets freshly injected traceparent/baggage and X-TUnit-TestId headers. Both factories share one helper, TUnitHttpClientFilter.CreateClient.

Tests

tests/TUnit.AspNetCore.Tests/ClientOptionsTests.cs covers both factory types:

• Cookie round-trip works by default.
• Redirects are followed by default.
• HandleCookies = false / AllowAutoRedirect = false are respected.
• BaseAddress is applied.
• Propagation headers are still sent by option-configured clients.

Without the fix, three TestWebApplicationFactory tests fail: cookies, redirects, and propagation headers with explicit options. The full TUnit.AspNetCore.Tests suite passes on net10.0 (103/103). TUnit.AspNetCore is not covered by the TUnit.PublicAPI snapshots.

Summary by CodeRabbit

• New Features
  • ASP.NET Core test clients now support configurable cookie handling, automatic redirects, and base addresses through client options.
  • TUnit propagation headers are preserved when creating clients with custom options, including requests that follow redirects.
  • Custom client configuration continues to apply when creating clients.

[chatgpt-codex-connector]

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📝 Code Review	✅ Completed 2026-09-29T14:47:19.890485Z	a4043ff	New commits

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• tests/TUnit.AspNetCore.Tests/ClientOptionsTests.cs

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• tests/TUnit.AspNetCore.Tests/ClientOptionsTests.cs

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📝 Walkthrough

Walkthrough

Client creation now applies WebApplicationFactoryClientOptions to redirect handling, cookie handling, and the base address. Both factory types retain TUnit propagation handlers. Regression tests cover these options and ConfigureClient overrides.

Changes

Client options handling

Layer / File(s)	Summary
Build handlers from client options src/TUnit.AspNetCore.Core/Http/TUnitHttpClientFilter.cs	The handler builder adds redirect and cookie handlers when the corresponding options are enabled. It then adds the activity-propagation and test-ID handlers.
Apply options in both factories src/TUnit.AspNetCore.Core/TestWebApplicationFactory.cs, src/TUnit.AspNetCore.Core/TracedWebApplicationFactory.cs	Both factories use client options to create clients. The options determine handlers and base address.
Verify client options behavior tests/TUnit.AspNetCore.Tests.WebApp/Program.cs, tests/TUnit.AspNetCore.Tests/ClientOptionsTests.cs	Test endpoints and regression tests check cookie handling, redirects, base address, propagation headers, and ConfigureClient overrides.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant Factory as TestWebApplicationFactory or TracedWebApplicationFactory
  participant Filter as TUnitHttpClientFilter
  participant Client as HttpClient
  Factory->>Filter: Create client with WebApplicationFactoryClientOptions
  Filter->>Client: Apply configured handlers
  Filter->>Client: Set BaseAddress from options

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Merge Risk: 🟡 Moderate · up to a4043

Kestrel-backed clients may still follow redirects and retain cookies when those options are disabled. Resolve this before merging unless the behavior is explicitly accepted.

Security Architecture Review

Security architecture risk: 🟡 Moderate · up to 7483d

Both test-factory APIs now honor client options, but automatically followed redirects also receive test-context headers. The security effect of redirects to another origin remains unverified.

Retained concerns

• Medium · security · inferred: Automatically followed redirects re-enter test-context propagation without a visible origin check. If the backing client can reach an external redirect destination, that destination may receive the test ID and activity context.

Security review details

Security Blast Radius

• inferred — The potential exposure is limited to requests made through these test-factory clients when redirects are enabled; external delivery has not been demonstrated.

Security Findings and Attack Paths

• inferred — A response that controls a redirect destination can cause the client to process another request through the propagation handlers. Whether that request can disclose context outside the application under test remains unresolved.

Trust Boundaries and Controls

• observed — Callers can disable automatic redirects and cookies independently; the disabling test covers both options. The changed handler construction contains no explicit redirect-origin check.

Hardening Proposals

• proposed — Verify cross-origin redirects with the supported backing transports and define whether test-context headers should be propagated beyond the factory origin.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 24 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes satisfy the coding requirements in [#6921]. TestWebApplicationFactory and TracedWebApplicationFactory now create clients from WebApplicationFactoryClientOptions. The implementation a…
Out of Scope Changes check	✅ Passed	The production changes implement option-aware client creation for [#6921]. The added endpoints and tests support cookie, redirect, base-address, propagation, and ConfigureClient behavior. No unrelat…
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: making CreateClient honor WebApplicationFactoryClientOptions for ASP.NET Core factories.

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And cookie crumbs come safely through.
Redirects follow when options say,
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[github-actions]

Review

The fix is well targeted. Mirroring the internal CreateHandlers() with public handler types avoids reflection, and the tests cover both factory types and the toggles.

Issues

1. ConfigureClient(client) is no longer called (TestWebApplicationFactory.CreateClient).

   • The old CreateClient() called ConfigureClient(client). That is the protected virtual hook users override to customise clients. The new CreateClient(options) drops the call.
   • Anyone overriding ConfigureClient would silently lose that behaviour, which is a regression. Please call it after setting BaseAddress and add a test with an override.
   • TracedWebApplicationFactory cannot call it because it is protected on the inner factory. That gap is worth documenting.

2. Option handling is duplicated.

   • The two CreateClient(options) bodies (CreateClientOptionsHandlers plus BaseAddress) are identical.
   • A shared helper, for example TUnitHttpClientFilter.CreateClient(Func<DelegatingHandler[], HttpClient> create, options), would keep them from drifting.

3. The handlers can diverge from upstream.

   • CreateClientOptionsHandlers re-implements internal logic. If ASP.NET adds a handler, this copy will not follow it.
   • The tests catch cookies and redirects only. A short comment naming the upstream version this mirrors would help.

4. Minor: BaseAddress can end up null.

   • client.BaseAddress = options.BaseAddress matches upstream, which defaults it to http://localhost. Users who set BaseAddress = null explicitly are unaffected.

Overall this is good, but please address #1 before merging.

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Reviewed commit: ba79eab9fa

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[greptile-apps]

Confidence Score: 5/5

[Medium risk] Test factory client creation now honors configuration options.

The PR appears safe to merge.

Summary

The PR makes both ASP.NET Core factory client paths honor client options while retaining TUnit propagation handlers.

• Adds cookie, redirect, and base-address handling through a shared client-creation helper.
• Adds regression tests for both factory paths and for propagation across redirects.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    A[Factory CreateClient] --> B[Shared client helper]
    B --> C[Optional redirect handler]
    C --> D[Optional cookie handler]
    D --> E[TUnit propagation handlers]
    E --> F[Factory CreateDefaultClient]

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Inline comments:
Review comments at @src/TUnit.AspNetCore.Core/Http/TUnitHttpClientFilter.cs:
- Line 56: Update the client-handler chain in TUnitHttpClientFilter so
Kestrel-backed clients use a terminal handler with automatic redirects and
cookies disabled, then place the configured redirect and cookie handlers above
it according to AllowAutoRedirect and HandleCookies. Apply this path to both
options overloads while preserving their existing option behavior.

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[thomhurst]

Replies to the github-actions review. Changes are in 7483db4.

1. ConfigureClient not called. It is still called. The new code calls the base WebApplicationFactory.CreateDefaultClient(DelegatingHandler[]), and that method calls ConfigureClient(client) before it returns (checked in Mvc.Testing 10.0.12). The old CreateClient() called it twice: once inside CreateDefaultClient, then again explicitly. The traced factory calls the inner factory's CreateDefaultClient, so the inner factory's override runs there too. BaseAddress is set after ConfigureClient, which is the same order as upstream CreateDefaultClient(Uri, handlers). I added ConfigureClientOverrideTests, which overrides ConfigureClient to add a header and asserts the server receives it.
2. Duplicated option handling. Fixed. Both overloads now call TUnitHttpClientFilter.CreateClient(createDefaultClient, options). The helper reads options.BaseAddress after the client is created, because starting a Kestrel-backed factory replaces ClientOptions.BaseAddress with the server's address.
3. Divergence from upstream. Added a doc comment. It says the handler list mirrors WebApplicationFactoryClientOptions.CreateHandlers in Mvc.Testing 8.0 to 10.0 (I checked all three) and must be updated if a later version adds a handler.
4. Null BaseAddress. No change. This matches upstream, as you noted.

Also in this push: the propagation handlers now sit inside RedirectHandler, so each redirect hop gets freshly injected headers. The traced factory now has tests for redirects and BaseAddress.

Tests: tests/TUnit.AspNetCore.Tests passes on net8.0 and net10.0 (108/108 on each).

[github-actions]

Review

Solid fix for #6921. I found no blocking issues.

• Approach: CreateClientOptionsHandlers reproduces the internal WebApplicationFactoryClientOptions.CreateHandlers() using public types, so it needs no reflection and stays AOT-safe. The base CreateDefaultClient is passed in as a delegate. That means the factory's ConfigureClient override still runs, and ConfigureClientOverrideTests covers it. Shadowing the CreateClient(options) overload closes the gap where the tracing and test-ID handlers were silently skipped.
• Handler order: The propagation handlers sit inside RedirectHandler and CookieContainerHandler, so every redirect hop gets fresh headers, and CreateClient_Redirect_KeepsPropagationHeadersOnRedirectedRequest tests this. The PR description says they "stay outermost, as before", which contradicts the code and its remarks. The code's behaviour is the better one, so update the description.
• BaseAddress: Reading it after client creation is correct, because a Kestrel-backed factory rewrites it on start. The comment explaining this is useful.
• Maintenance risk: Mirroring the internal handler list means a future Mvc.Testing release that adds a handler would silently diverge. The doc comment already says so. If you want a guard, add a test that compares the handler types against the base CreateClient result via the HttpClient handler chain. That's optional.
• Test nit: The comment in AssertRedirectedRequestHasTestIdHeader says "Exactly one value", but Contains on the lines array doesn't check for duplicates. Either assert the count of matching lines equals 1 or reword the comment.

Good test coverage across both factory types. LGTM.

[thomhurst]

Replies to the latest github-actions review. Changes are in a4043ff.

• PR description: fixed. It now says the propagation handlers sit inside RedirectHandler and CookieContainerHandler.
• "Exactly one value" comment: the assertion already checks this, and the comment now explains why. /echo-headers writes each header as {Key}: {StringValues}, and StringValues joins repeated values with commas. A duplicated header would print as X-TUnit-TestId: id,id, which does not match the exact line.
• Handler-list drift guard: not added. The base CreateClient result exposes only its outermost handler through a private field, so the test would need reflection. The doc comment already records this risk.

[github-actions]

Review of #6931

I found no blocking issues, and the fix looks correct.

• Matches the base behaviour. TUnitHttpClientFilter.CreateClient follows WebApplicationFactory.CreateClient(options). It calls CreateDefaultClient(handlers) and then sets BaseAddress from the options. Reading BaseAddress after client creation handles the Kestrel case, where starting the server rewrites it. The ConfigureClient override still runs, and ConfigureClientOverrideTests covers that.
• Handler order is right. The propagation handlers sit inside RedirectHandler and CookieContainerHandler, so every redirect hop gets fresh headers. CreateClient_Redirect_KeepsPropagationHeadersOnRedirectedRequest checks this, and the exact-line assertion also catches duplicated headers.
• Shadowed overload. Adding new CreateClient(WebApplicationFactoryClientOptions) closes the gap where that overload silently skipped tracing. TracedWebApplicationFactory now goes through the same helper, so the two factories don't drift.
• Tests. They cover both factory types, the defaults, the opt-outs, BaseAddress, and propagation headers with explicit options.

Non-blocking suggestions:

1. The helper mirrors the internal CreateHandlers() from Mvc.Testing 8.0 to 10.0. If a later version adds a handler, this will drift without any signal. The doc comment says so, but a small test that asserts the handler set for the default options would fail loudly when the mirror goes stale.
2. CreateClientOptionsHandlers only has a fixed-size array to fill, which is fine. If more handlers are ever added, a List<DelegatingHandler> would be easier to maintain than the hand-counted 2 + ....

Good to merge from my side.

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Cover the new overload in public-API snapshots

This overload and the matching TracedWebApplicationFactory.CreateClient(options) method expand the shipped public surface, but tests/TUnit.PublicAPI neither references nor snapshots TUnit.AspNetCore.Core, so these additions bypass API compatibility checks. Add the ASP.NET Core assembly to that suite and commit the per-TFM baselines for the new APIs.

AGENTS.md reference: AGENTS.md:L15-L16

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