"The response is not a view"; `Alert` output breaks `assertViewIs()` / `assertViewHas()` in PHPUnit tests

[kolydart]

I am sorry to drop here a description from ai chatbot (claude code), but this bug haunted me for years.
I did not even know it was from this package, until i tried the fix.
I just post the description here in case it is useful for other developers.

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Description

When the Alert output is enabled (the default), feature tests that use Laravel's view assertions can fail with:

The response is not a view.

…even though the response is HTTP 200, the session has no errors, and the controller did return a View.

Root cause

BeyondCode\QueryDetector\Outputs\Alert::output() injects the JS alert by calling:

$response->setContent($content);

Illuminate\Http\Response::setContent() unconditionally executes:

$this->original = $content;

at the top of the method. When $content is a string (as it is in Alert::output()), the original View object that Laravel had stored in $response->original is replaced by a raw string. From that point on, TestResponse::assertViewIs() / assertViewHas() / assertViewMissing() report "The response is not a view.", because they check $response->original instanceof View.

This is the same class of bug Livewire had with its auto-injected scripts, which they fixed in v3.4.0 (livewire/livewire PR #7758) by preserving $response->original after setContent.

Reproduction

1. Laravel app with beyondcode/laravel-query-detector installed, QUERY_DETECTOR_ENABLED=true, and Alert::class listed in config/querydetector.php output.

2. A route returning view('foo') that triggers ≥ threshold N+1 queries.

3. Test:

   $response = $this->get('/foo');
   $response->assertStatus(200);
   $response->assertViewIs('foo'); // ❌ "The response is not a view."

The failure happens only when N+1 queries are actually detected (i.e. the Alert output runs). Below the threshold the test passes, which makes it look intermittent.

Symptoms that make this hard to diagnose

• assertStatus(200) passes.
• assertSessionHasNoErrors() passes.
• Nothing is logged to laravel.log if only Alert::class is configured.
• The error message ("The response is not a view") points at the test, not the package, so users blame their view / Livewire / @include / a recent refactor.

Suggested fixes (in order of preference)

1. Restore $response->original after setContent inside Alert::output():

   $original = $response->original;
   $response->setContent($content);
   $response->original = $original;
   $response->headers->remove('Content-Length');

   This matches the approach Livewire adopted in v3.4.0.

2. Skip the Alert output in the testing environment, e.g. early-return when app()->runningUnitTests() (or when app()->environment('testing')). The injected JS alert() is never visible during tests anyway.

3. Document the caveat in docs/usage.md: recommend setting QUERY_DETECTOR_ENABLED=false for the testing environment (via phpunit.xml <env> or .env.testing) until a fix lands.

Workaround I'm using (until a fix is released)

Adding to phpunit.xml:

<env name="QUERY_DETECTOR_ENABLED" value="false"/>

This deactivates the entire detector during tests and the view assertions work again. The detector still runs normally in local/development.

Environment

• PHP 8.4
• Laravel 12
• Livewire 3 (with PowerGrid)
• beyondcode/laravel-query-detector (latest)