http-message VS openapi-httpfoundation-testing

There is a package within The PHP League that allows validation of an OpenAPI specification: league/openapi-psr7-validator. This package validates requests and responses to the PSR-7 specification.

PSR-7, the standard for requests and responses

Guzzle implements PSR-7: HTTP message interfaces (but apparently not yet PSR-18: HTTP Client, or at least they don't mention it). That means it's possible to use it in third-party libraries/frameworks and easy to replace with similar tools.

The Yii HTTP Application provides the Application::class, as well as the events and handlers needed to interact with HTTP. The package is implemented using PSR-7 and PSR-15 standards.

[PSR Http Message.](https://github.com/php-fig/http-message) This repository holds all interfaces/classes/traits related to [PSR-7](http://www.php-fig.org/psr/psr-7/).

PSR Http Message. This repository holds all interfaces/classes/traits related to PSR-7.

Since the library is designed to be easily integrated with different frameworks, it relies on the usage of PSR-7 compliant HTTP messages. To fulfill this requirement, I'll be using the nyholm/psr7 package.

Sounds good for the future given that PHP-FIG seems uninterested in maintaining the related code repo https://github.com/php-fig/http-message/pull/95

But then again, most PHP developers don't have to think about this too much. I personally started to look into compatibility testing more seriously when I created my first open-source library and, later on, when I started exploring building for the console with PHP.

All of these pieces form a jigsaw puzzle that the OpenAPI HttpFoundation Testing package sets out to solve for us, allowing developers to back their integration tests with OpenAPI definitions in applications relying on the HttpFoundation component.