Ruby exception handler that uses exception notifier to send exception notification and silently handles exception on production.

failsafe.rb

require 'exception_notification/rails'

# Capture errors in production and return nil
module Failsafe
  def failsafe(&_block)
    yield
  rescue => e
    # Show errors only during development
    if Rails.env.test? || Rails.env.development?
      raise e
    else
      # On production environments handle the error
      # but send email to developers with exception
      # ExceptionNotifier.notify_exception(
      #   exception, env: request.env,
      #              data: { message: 'Failsafe handled exception' }
      # )
      ::ExceptionNotifier.notify_exception(e, failsafe_params)
      nil
    end
  end

  # Allow classes to redefine method
  # this way you can send additional data in email
  def failsafe_params; end
end

failsafe_spec.rb

require 'rails_helper'

class FailsafeTestClass
  include Failsafe

  def unsafe_action
    failsafe { name }
  end

  def safe_action
    failsafe { 'success' }
  end

  private

  def name
    crashme
  end

  # Should be called and result sent in email
  def failsafe_params
    { data: 'some' }
  end
end

RSpec.describe Failsafe, type: :service do
  describe '.failsafe' do
    subject { FailsafeTestClass.new }

    it 'should fail silently on production' do
      expect(Rails.env).to receive(:test?).and_return(false)
      expect { subject.unsafe_action }.to_not raise_error
    end

    it 'should send email on production' do
      expect(Rails.env).to receive(:test?).and_return(false)
      expect(ExceptionNotifier).to receive(:notify_exception)
        .with(instance_of(NameError), hash_including(data: 'some'))
      subject.unsafe_action
    end

    it 'should explicitly fail during development' do
      expect { subject.unsafe_action }.to raise_error(NameError)
    end

    it 'should return value in case of no failure' do
      expect(subject.safe_action).to eq 'success'
    end
  end
end