[10.x] Adds testing helpers for Precognition (#48151)

* adds testing helpers for Precognition

* Review changes

* Fix comment

* fix comment

* Add functional test to precog test

* Add assertNoContent to response assertion

* Fixes

* Update MakesHttpRequests.php

* formatting

---------

Co-authored-by: Tim MacDonald <hello@timacdonald.me>
Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Foundation/Testing/Concerns/MakesHttpRequests.php

@@ -309,6 +309,16 @@ public function from(string $url)
         return $this->withHeader('referer', $url);
     }
 
+    /**
+     * Set the Precognition header to "true".
+     *
+     * @return $this
+     */
+    public function withPrecognition()
+    {
+        return $this->withHeader('Precognition', 'true');
+    }
+
     /**
      * Visit the given URI with a GET request.
      *

src/Illuminate/Testing/TestResponse.php

@@ -95,6 +95,29 @@ public function assertSuccessful()
         return $this;
     }
 
+    /**
+     * Assert that the Precognition request was successful.
+     *
+     * @return $this
+     */
+    public function assertSuccessfulPrecognition()
+    {
+        $this->assertNoContent();
+
+        PHPUnit::assertTrue(
+            $this->headers->has('Precognition-Success'),
+            'Header [Precognition-Success] not present on response.'
+        );
+
+        PHPUnit::assertSame(
+            'true',
+            $this->headers->get('Precognition-Success'),
+            'The Precognition-Success header was found, but the value is not `true`.'
+        );
+
+        return $this;
+    }
+
     /**
      * Assert that the response is a server error.
      *

tests/Foundation/Testing/Concerns/MakesHttpRequestsTest.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Contracts\Routing\Registrar;
 use Illuminate\Contracts\Routing\UrlGenerator;
+use Illuminate\Foundation\Http\Middleware\HandlePrecognitiveRequests;
 use Illuminate\Http\RedirectResponse;
 use Orchestra\Testbench\TestCase;
 
@@ -186,6 +187,19 @@ public function testFollowingRedirectsTerminatesInExpectedOrder()
 
         $this->assertEquals(['from', 'to'], $callOrder);
     }
+
+    public function testWithPrecognition()
+    {
+        $this->withPrecognition();
+        $this->assertSame('true', $this->defaultHeaders['Precognition']);
+
+        $this->app->make(Registrar::class)
+            ->get('test-route', fn () => 'ok')->middleware(HandlePrecognitiveRequests::class);
+        $this->get('test-route')
+            ->assertStatus(204)
+            ->assertHeader('Precognition', 'true')
+            ->assertHeader('Precognition-Success', 'true');
+    }
 }
 
 class MyMiddleware

tests/Testing/TestResponseTest.php

@@ -1035,6 +1035,32 @@ public function testAssertHeaderMissing()
         $response->assertHeaderMissing('Location');
     }
 
+    public function testAssertPrecognitionSuccessfulWithMissingHeader()
+    {
+        $this->expectException(AssertionFailedError::class);
+        $this->expectExceptionMessage('Header [Precognition-Success] not present on response.');
+
+        $baseResponse = new Response('', 204);
+
+        $response = TestResponse::fromBaseResponse($baseResponse);
+
+        $response->assertSuccessfulPrecognition();
+    }
+
+    public function testAssertPrecognitionSuccessfulWithIncorrectValue()
+    {
+        $this->expectException(AssertionFailedError::class);
+        $this->expectExceptionMessage('The Precognition-Success header was found, but the value is not `true`.');
+
+        $baseResponse = tap(new Response('', 204), function ($response) {
+            $response->header('Precognition-Success', '');
+        });
+
+        $response = TestResponse::fromBaseResponse($baseResponse);
+
+        $response->assertSuccessfulPrecognition();
+    }
+
     public function testAssertJsonWithArray()
     {
         $response = TestResponse::fromBaseResponse(new Response(new JsonSerializableSingleResourceStub));