Dmm/add invalid sig errors

[Sgtpluck]

This change:

• Passes a require_auth_errors option through the validation methods to trigger validation failures as a way of passing more meaningful errors through
• Adds an error dictionary to catch validation errors and return translatable keywords
• Adds tests to make sure right certificates are being used, and that a partner can't pass a certificate through the SAML request that is not registered in the IdP
• Updates the tests to use request macros instead of hard-coding XML
• Updates the request macros to be more configurable (this could use some more cleanup)

[zachmargolis]

1. do we need to have a default mesage here if the dictionary doesn't have a matching error?
2. the dictionary keys appear to be symbols but e.message looks like it will be strings

[Sgtpluck]

1. i included all possible ValidationErrors that could pop up (and some that actually i think are impossible for us to reach, but wanted to keep them there for the moment until we refactored the code) so it didn't feel strictly necessary. happy to add a default if you disagree![
2. i threw a with_indifferent_access in there but i can change it to the hash rockets if you'd prefer, i just think they're kind ugly!

[zachmargolis]

1. I didn't realize our own code threw those errors, if it's more limited that seems fine then. Maybe we just update each time we throw to have its own error_code property or something do we can do e.error_code instead of a reverse lookup
   So like...

   raise SamlIdp::XMLSecurity::SignedDocument::ValidationError.new('error message', error_code: :some_symbole_thing_here)

2. I missed the with_indifferent_access that seems fine

[zachmargolis]

if we're switching to a find, the block just needs to return true so we can get rid of the if and just have that condition be the body

      @matching_cert = Array(certs).find do |cert|
        doc.valid_signature?(fingerprint_cert(cert), options.merge(cert: cert))
      end

[Sgtpluck]

updated in 0d555da

[zachmargolis]

LGTM! Thanks for adding the error code to the error class itself!

Also don't forget to bump the gem version before merging!

[Sgtpluck]

i really want to fix the tests in this file (and spec/support/security_helpers.rb but this scope has already gotten expanded so left a TODO in security_helpers.rb

[Sgtpluck]

this PR is stale -- reference only