Laravel Assertable Json

How to use Laravel’s fluent json assertions effectively

Photo by Jason Briscoe on Unsplash

Introduction

Laravel offers many json testing methods but recently brought out a fluent way to test JSON responses. We need to pass a closure to the assertJson method, which can then be used to make assertions against attributes of the json.

Fluent JSON allows us to target certain aspects of a JSON response more specifically than some traditional testing methods such as assertJsonFragment or assertJsonMissing.

Example

Say we have an endpoint which returns a specific vehicle object, we could write a test in this form:

public function test_fluent_json()
{
   $response = $this->getJson('/vehicles/1');
   $response
      ->assertJson(fn (AssertableJson $json) =>
         $json->where('id', 1)
            ->where('name', 'Model T')
            ->missing('new')
            ->etc()
   );
}

This will check that the item returned has id equal to ‘1’, name equal to ‘Model T’, with no property called ‘new’ and the test will ignore if there are any other properties. We will look at how this is works below.

Photo by Jan Kopřiva on Unsplash

Useful methods

has method

The ‘has’ method allows us to assert that an attribute is present in the JSON response.

Assert a response has the key description :

$response->assertJson(fn (AssertableJson $json) =>
   $json->has('description');
);

Assert a response has 3 objects:

$response->assertJson(fn (AssertableJson $json) =>
   $json->has(3);
);

Assert the response has an array with 4 items called vehicles, where the first item has id ‘5’ and name ‘Model S’:

$response->assertJson(fn (AssertableJson $json) =>
   $json->has('vehicles', 3)
      ->has('vehicle.0', fn ($json) =>
         $json->where('id', 5)
            ->where('name', 'Model S')
      )
);

missing method

The missing method allows us to check that the property does NOT exist — such as a user’s password.

Photo by Pawel Czerwinski on Unsplash

etc method

By default, if you return more json in your response object than in your test, your test will fail. This makes sense as there may be sensitive information returned in your response that your test will not cover. However, if we only care about a few properties then we can use the etc method to disable the check for ‘all properties’ on that json object, allowing the test to pass without having to test for every property.

Conclusion

It’s always important to test your api thoroughly and for this purpose Laravel provides some neat ways to test your JSON responses. Releasing fluent JSON has allowed more flexible testing, allowing data to be accessed as array variables on the JSON response.