Add have_http_link_header matcher

spec/support/matchers/http_link_header.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+RSpec::Matchers.define :have_http_link_header do |rel, href|
+  chain :with_type do |type|
+    @type = type
+  end
+
+  match do |response|
+    header_link = link_for(response, rel)
+
+    header_link.href == href &&
+      (@type.nil? || header_link.attrs['type'] == @type)
+  end
+
+  match_when_negated do |response|
+    response.headers['Link'].blank?
+  end
+
+  failure_message do |response|
+    (+'').tap do |string|
+      string << "Expected `#{response.headers['Link']}` to include `href` value of `#{href}` "
+      string << "with `type` of `#{@type}` " if @type.present?
+      string << "for `rel=#{rel}` but it did not."
+    end
+  end
+
+  def link_for(response, rel)
+    LinkHeader
+      .parse(response.headers['Link'])
+      .find_link(['rel', rel.to_s])
+  end
+end
+
+RSpec::Matchers.define_negated_matcher :not_have_http_link_header, :have_http_link_header # Allow chaining