RSpec - Stub Graphql Client Adapter

platform_graphql_client.rb

require 'graphql/client'
require 'graphql/client/http'

module PlatformGraphqlClient
  # Configure GraphQL endpoint using the basic HTTP network adapter.
  HTTP = GraphQL::Client::HTTP.new('http://localhost:3001/api/graphql') do
    # def headers(context)
    #   # Optionally set any HTTP headers
    #   { "Access-Token": "user-access-token" }
    # end
  end

  begin
    # Fetch latest schema on init, this will make a network request
    SCHEMA = GraphQL::Client.load_schema(HTTP)

    # However, it's smart to dump this to a JSON file and load from disk
    #
    # Run it from a script or rake task
    #   GraphQL::Client.dump_schema(CoreGraphql::HTTP, "path/to/schema.json")
    #
    # SCHEMA = GraphQL::Client.load_schema("path/to/schema.json")
    #
    CLIENT = GraphQL::Client.new(schema: SCHEMA, execute: HTTP)
  rescue Errno::ECONNREFUSED
    raise 'Graphql could not load schema. The Host URL is invalid/empty.'
  end
end

rspec_stub_graphql_client_adapter.rb

# Stubbed Adapter for Graphqal Client object
class StubGraphqlClientAdapter
  def self.execute(document: _, operation_name: _, variables: _, context: _)
    custom_response = StubGraphqlCustomResponseGenerator.instance.notify_observers(operation_name)
    StubGraphqlCustomResponseGenerator.instance.changed(true) if StubGraphqlCustomResponseGenerator.instance.count_observers > 0
    return custom_response if custom_response
    
    case operation_name
      when 'ValidateUserEmailQuery'
        { data: { validateUserExistence: false } }.with_indifferent_access
      when 'CreateUserQuery'
        { data: { createUser: variables } }.with_indifferent_access
      else
        { data: {} }
    end
  end
end

### CUSTOM STUBBED RESPONSE DURING TEST CASES ###

# If you want to generate a custom response in your specifc RSpec spec for a Graphql Query/Mutation you can use StubGraphqlCustomResponseGenerator in RSpec before hooks, which is singleton btw, and set custom mocked responses.
# All it does is allow you to subscribe multiple observers (which are objects of StubGraphqlCustomResponse) and inside `StubGraphqlCustomResponse.execute`
# it publishes those observers. You can add multiple observers at time, they'll be published sequentially everytime #execute is called.
#
# Usage Examples
#
# before do
#   StubGraphqlCustomResponseGenerator.instance.add_response(
#     StubGraphqlCustomResponse.new('validateUserExistence', { data: { validateUserExistence: true } }.with_indifferent_access })
#   )
#   StubGraphqlCustomResponseGenerator.instance.add_response(
#     StubGraphqlCustomResponse.new('CreateUserQuery', { { errors: [ { message: "can't be blank ", extensions: { code: "USER_INPUT_ERROR", attribute: "password" } }] }.with_indifferent_access })
#   )
# end
#
# it 'should see errors from third party' do
#   # Your test definition of a method that will hit Graphql api....
# end
#
class StubGraphqlCustomResponseGenerator
  include Singleton
  include Observable

  def add_observer(observer)
    super(observer)
    changed(true)
  end
  alias_method :add_response, :add_observer

  def notify_observers(*arg)
    if defined? @observer_state and @observer_state
      if defined? @observer_peers
        @observer_state = false
        # Always return executed response from StubGraphqlCustomResponse#update and reject nils
        @observer_peers.map do |k, v|
          k.send(v, *arg)
        end.compact.first
      end
    end
  end
  alias_method :collect_response, :notify_observers
end

class StubGraphqlCustomResponse
  def initialize(key, response)
    @key      = key
    @response = response
  end

  def update(operation_name)
    if @key == operation_name
      StubGraphqlCustomResponseGenerator.instance.delete_observer(self)
      @response
    end
  end
end


## Finally set `StubGraphqlClientAdapter`
#
# Reset your default Adapter (GraphQL::Client::HTTP) object in your initializer (I've set inside HTTP constant) with the `StubGraphqlClientAdapter`
PlatformGraphqlClient.remove_const('HTTP')
PlatformGraphqlClient.const_set('HTTP', StubGraphqlClientAdapter)

# OR

# Reset your default Client object in your initializer (I've set inside CLIENT constant) with a new Client object that can use
# the same (default) scehema but for execution, it should use `StubGraphqlClientAdapter` class instead of GraphQL::Client::HTTP.
PlatformGraphqlClient.remove_const('CLIENT')
PlatformGraphqlClient.const_set('CLIENT', GraphQL::Client.new(schema: PlatformGraphqlClient::SCHEMA, execute: StubGraphqlClientAdapter))

Place above file in your spec directory.