Add RSpec for high-level integration testing

spec/spec_helper.rb

@@ -0,0 +1,13 @@
+require 'rspec/wait'
+
+RSpec.configure do |config|
+  config.expect_with :rspec do |expectations|
+    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
+  end
+
+  config.mock_with :rspec do |mocks|
+    mocks.verify_partial_doubles = true
+  end
+
+  config.wait_timeout = 2
+end