Add `have_http_link_header` matcher and set header values as strings (#31010)

app/controllers/concerns/account_controller_concern.rb

@@ -20,7 +20,7 @@ module AccountControllerConcern
         webfinger_account_link,
         actor_url_link,
       ]
-    )
+    ).to_s
   end
 
   def webfinger_account_link

app/controllers/concerns/api/pagination.rb

@@ -19,7 +19,7 @@ module Api::Pagination
     links = []
     links << [next_path, [%w(rel next)]] if next_path
     links << [prev_path, [%w(rel prev)]] if prev_path
-    response.headers['Link'] = LinkHeader.new(links) unless links.empty?
+    response.headers['Link'] = LinkHeader.new(links).to_s unless links.empty?
   end
 
   def require_valid_pagination_options!

app/controllers/statuses_controller.rb

@@ -56,7 +56,9 @@ class StatusesController < ApplicationController
   end
 
   def set_link_headers
-    response.headers['Link'] = LinkHeader.new([[ActivityPub::TagManager.instance.uri_for(@status), [%w(rel alternate), %w(type application/activity+json)]]])
+    response.headers['Link'] = LinkHeader.new(
+      [[ActivityPub::TagManager.instance.uri_for(@status), [%w(rel alternate), %w(type application/activity+json)]]]
+    ).to_s
   end
 
   def set_status

spec/controllers/concerns/account_controller_concern_spec.rb

@@ -54,17 +54,12 @@ RSpec.describe AccountControllerConcern do
     it 'Prepares the account, returns success, and sets link headers' do
       get 'success', params: { account_username: account.username }
 
-      expect(response).to have_http_status(200)
-      expect(response.headers['Link'].to_s).to eq(expected_link_headers)
+      expect(response)
+        .to have_http_status(200)
+        .and have_http_link_header('http://test.host/.well-known/webfinger?resource=acct%3Ausername%40cb6e6126.ngrok.io').for(rel: 'lrdd', type: 'application/jrd+json')
+        .and have_http_link_header('https://cb6e6126.ngrok.io/users/username').for(rel: 'alternate', type: 'application/activity+json')
       expect(response.body)
         .to include(account.username)
     end
-
-    def expected_link_headers
-      [
-        '<http://test.host/.well-known/webfinger?resource=acct%3Ausername%40cb6e6126.ngrok.io>; rel="lrdd"; type="application/jrd+json"',
-        '<https://cb6e6126.ngrok.io/users/username>; rel="alternate"; type="application/activity+json"',
-      ].join(', ')
-    end
   end
 end

spec/requests/accounts_spec.rb

@@ -69,8 +69,7 @@ RSpec.describe 'Accounts show response' do
             expect(response)
               .to have_http_status(200)
               .and render_template(:show)
-
-            expect(response.headers['Link'].to_s).to include ActivityPub::TagManager.instance.uri_for(account)
+              .and have_http_link_header(ActivityPub::TagManager.instance.uri_for(account)).for(rel: 'alternate')
           end
         end
 

spec/requests/api/v1/timelines/home_spec.rb

@@ -94,8 +94,9 @@ RSpec.describe 'Home', :inline_jobs do
       it 'returns http unprocessable entity', :aggregate_failures do
         subject
 
-        expect(response).to have_http_status(422)
-        expect(response.headers['Link']).to be_nil
+        expect(response)
+          .to have_http_status(422)
+          .and not_have_http_link_header
       end
     end
   end

spec/requests/api/v1/timelines/list_spec.rb

@@ -47,8 +47,9 @@ RSpec.describe 'API V1 Timelines List' do
       it 'returns http unprocessable entity' do
         get "/api/v1/timelines/list/#{list.id}", headers: headers
 
-        expect(response).to have_http_status(422)
-        expect(response.headers['Link']).to be_nil
+        expect(response)
+          .to have_http_status(422)
+          .and not_have_http_link_header
       end
     end
   end

spec/requests/link_headers_spec.rb

@@ -6,28 +6,12 @@ RSpec.describe 'Link headers' do
   describe 'on the account show page' do
     let(:account) { Fabricate(:account, username: 'test') }
 
-    before do
+    it 'contains webfinger and activitypub urls in link header' do
       get short_account_path(username: account)
-    end
 
-    it 'contains webfinger url in link header' do
-      link_header = link_header_with_type('application/jrd+json')
-
-      expect(link_header.href).to eq 'https://cb6e6126.ngrok.io/.well-known/webfinger?resource=acct%3Atest%40cb6e6126.ngrok.io'
-      expect(link_header.attr_pairs.first).to eq %w(rel lrdd)
-    end
-
-    it 'contains activitypub url in link header' do
-      link_header = link_header_with_type('application/activity+json')
-
-      expect(link_header.href).to eq 'https://cb6e6126.ngrok.io/users/test'
-      expect(link_header.attr_pairs.first).to eq %w(rel alternate)
-    end
-
-    def link_header_with_type(type)
-      LinkHeader.parse(response.headers['Link'].to_s).links.find do |link|
-        link.attr_pairs.any?(['type', type])
-      end
+      expect(response)
+        .to have_http_link_header('https://cb6e6126.ngrok.io/.well-known/webfinger?resource=acct%3Atest%40cb6e6126.ngrok.io').for(rel: 'lrdd', type: 'application/jrd+json')
+        .and have_http_link_header('https://cb6e6126.ngrok.io/users/test').for(rel: 'alternate', type: 'application/activity+json')
     end
   end
 end

spec/support/matchers/api_pagination.rb

@@ -3,7 +3,7 @@
 RSpec::Matchers.define :include_pagination_headers do |links|
   match do |response|
     links.map do |key, value|
-      response.headers['Link'].find_link(['rel', key.to_s]).href == value
+      expect(response).to have_http_link_header(value).for(rel: key.to_s)
     end.all?
   end
 

spec/support/matchers/http_link_header.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+RSpec::Matchers.define :have_http_link_header do |href|
+  match do |response|
+    @response = response
+
+    header_link&.href == href
+  end
+
+  match_when_negated do |response|
+    response.headers['Link'].blank?
+  end
+
+  chain :for do |attributes|
+    @attributes = attributes
+  end
+
+  failure_message do |response|
+    "Expected `#{response.headers['Link']}` to include `href` value of `#{href}` for `#{@attributes}` but it did not."
+  end
+
+  failure_message_when_negated do
+    "Expected response not to have a `Link` header but `#{response.headers['Link']}` is present."
+  end
+
+  def header_link
+    LinkHeader
+      .parse(@response.headers['Link'])
+      .find_link(*@attributes.stringify_keys)
+  end
+end
+
+RSpec::Matchers.define_negated_matcher :not_have_http_link_header, :have_http_link_header # Allow chaining