GUILD-522: Add ability to generate schema model classes from schemas

[DeeChau]

Description

New Feature - Schema Class Generation

Offer a way to generate classes from Avro schemas. These classes are documented with YARD to aid in IDE auto-complete, and will help to move errors closer to the code. These classes can be used in your application through the Consumer and Producer.

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] This change requires a documentation update

How Has This Been Tested?

• [x] Created new and updated existing unit tests in Deimos
• [x] Set up in applications currently using Deimos - verified that existing functionality does not break

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] I have added a line in the CHANGELOG describing this change, under the UNRELEASED heading
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules

Suggested order of files to look at

• README.md, CONFIGURATION.md
• Generate Schema classes from Avro Schemas
  • schema_record.rb, schema_enum.rb
  • schema_class_generator.rb, schema_class_mixin.rb
  • schema_record.rb.tt, schema_enum.rb.tt
  • spec/schema_classes/ - Examples of classes generated from schemas
  • spec/generators/schema_class_generator_spec.rb
  • spec/generators/schema_class/
• Use Schema Classes in your consumer/producer interfaces
  • configuration.rb
  • consumer.rb, message_consumption.rb, batch_consumption.rb
  • active_record_consume/batch_consumption.rb
  • spec/consumer_spec.rb, spec/batch_consumer_spec.rb
  • spec/active_record_consumer_spec.rb, spec/active_record_batch_consumer_spec.rb
  • producer.rb, active_record_producer.rb
  • spec/active_record_producer_spec.rb, spec/producer_spec.rb
• Miscellaneous
  • guardfile generation

[DeeChau]

Am not too sure why the rspecs are failing on CircleCI, ssh'ed into the machine and verified that the generated files are both the same (there's no noticeable diff between them)

Will review this later.

edit: Got it working, was trying to compare my_schema.rb with my_schemakey.rb ..

[dorner]

LGTM! Awesome job Derek, I think this is one of the biggest changes we've ever made, and definitely the biggest done by anybody other than me. :D