[REQ] PHPUnit test generation

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.

Start from the OpenAPI definition and the generator's PHP output path, then review how generated API tests could represent general response checks. Compare the desired PHPUnit-compatible class with the linked Guzzle example; done means a defined generation scope and working PHPUnit tests for the applicable endpoints.