add lazy_spec.rb

spec/config/lazy_spec.rb

@@ -0,0 +1,13 @@
+require 'helper'
+RSpec.describe Pry::Config::Lazy do
+  let(:lazyobject) do
+    Class.new do
+      include Pry::Config::Lazy
+      lazy_implement({foo: proc {"bar"}})
+    end.new
+  end
+
+  it 'memorizes value after first call' do
+    expect(lazyobject.foo).to equal(lazyobject.foo)
+  end
+end