Verify JSON validation errors

[Startouf]

Following the https://jsonapi-suite.github.io/jsonapi_errorable/ documentation, it would be great to be able to verify automatically the presence of errors in the JSON response

Suppose I have an error response like this

{
    "errors" => [
        [0] {
              "code" => "unprocessable_entity",
            "status" => "422",
             "title" => "Validation Error",
            "detail" => "Billing_vat_number is not a valid european VAT number",
            "source" => {
                "pointer" => "/data/attributes/billing_vat_number"
            },
              "meta" => {
                "attribute" => "billing_vat_number",
                  "message" => "this is not a valid european VAT number"
            }
        }
    ]
}

a nice Jsonapi spec matcher helper should let us write something like

expect(response).to have_jsonapi_errors([
  'billing_vat_number, :not_eu_vat'
])

What do you think ?