Add have_http_header rspec matcher

spec/support/matchers/http_headers.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+RSpec::Matchers.define :have_http_header do |header, values|
+  match do |response|
+    response.headers[header].match?(values)
+  end
+
+  failure_message do |response|
+    "Expected that `#{header}` would have values of `#{values}` but was `#{response.headers[header]}`"
+  end
+end