[REQ] PHPUnit test generation

[powtac]

Is your feature request related to a problem? Please describe.

no

Describe the solution you'd like

From the API definition it is possible to generate general end-to-end API tests in a PHPUnit compatible class format. All general things could be an object to be tested. Example: API returns a Content-Type: this could be tested.

Describe alternatives you've considered

Along with the given API specs it is possible to write API tests manually.

Additional context

• https://blog.cloudflare.com/using-guzzle-and-phpunit-for-rest-api-testing/ Excellent example of an API test in PHPUnit format.

This is how to test an endpoint that will respond with 405 on a PUT request:

public function testPut() {
    $response = $this->http->request('PUT', 'user-agent', ['http_errors' => false]);
    $this->assertEquals(405, $response->getStatusCode());
}

Maybe this is related to #566 but the solution there looks like it is related to slim framework only.

[wing328]

For PHP clients, there are auto-generated test files, e.g. https://github.com/OpenAPITools/openapi-generator/blob/master/samples/client/petstore/php/OpenAPIClient-php/test/Api/PetApiTest.php

We can make further enhancements like what you've suggested.