TestResponse fromJsonString() macro

ExampleTest.php

<?php

namespace Tests\Feature;

use Illuminate\Foundation\Testing\TestResponse;
use Tests\TestCase;

class ExampleTest extends TestCase
{
    public function testExample()
    {
        $response = TestResponse::fromJsonString(
            file_get_contents('http://example.com/test.json')
        );
        
        $response->assertJsonFragment(
            //
        );
    }
}

TestCase.php

<?php

namespace Tests;

use Illuminate\Foundation\Testing\TestCase as BaseTestCase;

abstract class TestCase extends BaseTestCase
{
    use CreatesApplication;
    
    protected function setUp()
    {
        parent::setUp();
        
        TestResponse::macro('fromJsonString', function ($string) {
            return TestResponse::fromBaseResponse(
                (new Response)->setContent($string)
            );
        });
    }
}