GraphQL::SchemaComparator

GraphQL::SchemaComparator is a GraphQL Schema comparator. What does that mean? GraphQL::SchemaComparator takes two GraphQL schemas and outputs a list of changes that happened between the two versions. This is useful for many things:

Breaking Change detection
Applying custom rules to schema changes
Building automated tools like linters

Installation

Add this line to your application's Gemfile:

gem 'graphql-schema_comparator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install graphql-schema_comparator

CLI

GraphQL::SchemaComparator comes with a handy CLI to help compare two schemas using the commandline.

After a gem install graphql-schema_comparator, use the CLI this way:

Commands:
  graphql-schema compare OLD_SCHEMA NEW_SCHEMA  # Compares OLD_SCHEMA with NEW_SCHEMA and returns a list of changes
  graphql-schema help [COMMAND]                 # Describe available commands or one specific command

Where OLD_SCHEMA and NEW_SCHEMA can be a string containing a schema IDL or a filename where that IDL is located.

Example

Usage

GraphQL::SchemaComparator, provides a simple api for Ruby applications to use.

GraphQL::SchemaComparator.compare

The compare method takes two arguments, old_schema and new_schema, the two schemas to compare.

You may provide schema IDL as strings, or provide instances of GraphQL::Schema.

The result of compare returns a SchemaComparator::Result object, from which you can access information on the changes between the two schemas.

result.breaking? returns true if any breaking changes were found between the two schemas
result.identical? returns true if the two schemas were identical
result.breaking_changes returns the list of breaking changes found between schemas.
result.non_breaking_changes returns the list of non-breaking changes found between schemas.
result.changes returns the full list of change objects.

Change Objects

Change objects are considered any objects that respond to message and breaking and they are all namespaced under the Changes module.

Possible changes are all found in changes.rb.

TODO

Handle changes in schema directives
Test each differ

Development

After checking out the repo, run bin/setup to install dependencies. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/xuorig/graphql-schema_comparator. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

swalkinshaw / graphql-schema_comparator