Added RSpec shared endpoint examples

Necessary to a define shared example for all endpoints to reduce duplication. This'll soon be used in all endpoint specs.

Milestone: minor

spec/spec_helper.rb

@@ -23,6 +23,7 @@ SPEC_ROOT = Pathname(__dir__).realpath.freeze
 using Refinements::Pathname
 
 Pathname.require_tree SPEC_ROOT.join("support/shared_contexts")
+Pathname.require_tree SPEC_ROOT.join("support/shared_examples")
 
 RSpec.configure do |config|
   config.color = true

spec/support/shared_examples/an_inspectable_endpoint.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+RSpec.shared_examples "an inspectable endpoint" do |target|
+  it "answers contract class" do
+    expect(target.inspect).to include("@contract=Dry::Schema::JSON, ")
+  end
+end