gruf-rspec

Assistance helpers and custom type for easy testing Gruf controllers with RSpec.

gem 'gruf-rspec'

Note that this gem requires at least Ruby 3.0+, Gruf 2.5.1+, and RSpec 3.8+.

• Add a test for a Gruf controller in spec/rpc
• Run the run_rpc method with three args: The gRPC method name, the request object and the active_call_options. The third argument is optional.
• Validate the response

Let's assume you have a gruf controller named ThingController that is bound to the gRPC service Rpc::Things::Service. That has a method GetThing:

class ThingController < Gruf::Controllers::Base
  bind ::Rpc::Things::Service

  def get_thing
    Rpc::GetThingResponse.new(id: request.message.id)
  end
end

To test it, you'd create spec/rpc/thing_controller_spec.rb:

describe ThingController do
  describe '#get_thing' do
    let(:request_proto) { Rpc::GetThingRequest.new(id: rand(1..100)) }
    let(:metadata) {
      { 'user_id' => 'axj42i' }
    }

    subject { run_rpc(:GetThing, request_proto, active_call_options: { metadata: metadata }) }

    it 'returns the thing' do
      expect(subject).to be_a_successful_rpc
      expect(subject.id).to eq request_proto.id
    end
  end
end

Alternatively, you can pass a block:

it 'returns the thing' do
  run_rpc(:GetThing, request_proto) do |resp|
    expect(resp).to be_a_successful_rpc
    expect(resp.id).to eq request_proto.id
  end
end

Note that you can also access the bound gRPC service class:

it 'binds the service correctly' do
  expect(grpc_bound_service).to eq Rpc::Things::Service
end

You can match against errors as well:

describe 'testing an error' do
  let(:request_proto) { Rpc::GetThingRequest.new(id: rand(1..100)) }

  subject { run_rpc(:GetThing, request_proto) }

  it 'fails with the appropriate error' do
    expect { subject }.to raise_rpc_error(GRPC::InvalidArgument)
  end
end

Or further, even check your serialized error that is passed in metadata:

it 'fails with the appropriate error code' do
  expect { subject }.to raise_rpc_error(GRPC::InvalidArgument).with_serialized { |err|
    expect(err).to be_a(MyCustomErrorClass)
    expect(err.error_code).to eq 'invalid_request'

    fe = err.field_errors.first
    expect(fe.field_name).to eq 'name'
    expect(fe.error_code).to eq 'invalid_name'
    expect(fe.error_message).to eq 'That name is already taken!'
  }
end

Note that when using with_serialized, you must pass the block with { }, not using do and end.

By default, the type matcher for Gruf controllers matches in /spec/rpc. You can customize this by configuring it in the Gruf::Rspec configuration block like so:

Gruf::Rspec.configure do |c|
  c.rpc_spec_path = '/spec/rpc_controllers'
end

Alternatively, you can pass configuration of the path via ENV. For example, where RPC_SPEC_PATH="/spec/rpc_controllers" is set in a .env file:

bundle exec dotenv rspec

Or, add require: false to the gemspec for the gruf-rspec gem, and then explicitly require it after setting the ENV var:

Dotenv.load # assuming the .env file has the RPC_SPEC_PATH var set
# or:
ENV['RPC_SPEC_PATH'] = '/spec/rpc_controllers'
require 'gruf/rspec'

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