Handle HTTP 302 without Location

nanoc/lib/nanoc/checking/checks/external_links.rb

@@ -74,15 +74,8 @@ def validate(href)
             return Result.new(href, 'too many redirects')
           end
 
-          # Find proper location
-          location = res['Location']
-          if location !~ /^https?:\/\//
-            base_url = url.dup
-            base_url.path = (location =~ /^\// ? '' : '/')
-            base_url.query = nil
-            base_url.fragment = nil
-            location = base_url.to_s + location
-          end
+          location = extract_location(res, url)
+          return Result.new(href, 'redirection without a target location') if location.nil?
 
           url = URI.parse(location)
         elsif res.code == '200'
@@ -98,6 +91,23 @@ def validate(href)
       end
     end
 
+    def extract_location(res, url)
+      location = res['Location']
+
+      case location
+      when nil
+        nil
+      when /^https?:\/\//
+        location
+      else
+        base_url = url.dup
+        base_url.path = (location =~ /^\// ? '' : '/')
+        base_url.query = nil
+        base_url.fragment = nil
+        base_url.to_s + location
+      end
+    end
+
     def path_for_url(url)
       path =
         if url.path.nil? || url.path.empty?

nanoc/spec/nanoc/checking/checks/external_links_spec.rb

@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+describe ::Nanoc::Checking::Checks::ExternalLinks do
+  let(:check) do
+    Nanoc::Checking::Checks::ExternalLinks.create(site).tap do |c|
+      def c.request_url_once(_url)
+        Net::HTTPResponse.new('1.1', '200', 'okay')
+      end
+    end
+  end
+
+  let(:site) do
+    Nanoc::Int::Site.new(
+      config: config,
+      code_snippets: code_snippets,
+      data_source: Nanoc::Int::InMemDataSource.new(items, layouts),
+    )
+  end
+
+  let(:config)        { Nanoc::Int::Configuration.new.with_defaults }
+  let(:code_snippets) { [] }
+  let(:items)         { Nanoc::Int::ItemCollection.new(config, []) }
+  let(:layouts)       { Nanoc::Int::LayoutCollection.new(config, []) }
+
+  before do
+    FileUtils.mkdir_p('output')
+    File.write('output/hi.html', '<a href="http://example.com/x">stuff</a>')
+    File.write('Rules', 'passthrough "/**/*"')
+  end
+
+  context 'found' do
+    let(:check) do
+      Nanoc::Checking::Checks::ExternalLinks.create(site).tap do |c|
+        def c.request_url_once(_url)
+          Net::HTTPResponse.new('1.1', '200', 'okay')
+        end
+      end
+    end
+
+    it 'has no issues' do
+      check.run
+      expect(check.issues).to be_empty
+    end
+  end
+
+  context 'not found' do
+    let(:check) do
+      Nanoc::Checking::Checks::ExternalLinks.create(site).tap do |c|
+        def c.request_url_once(_url)
+          Net::HTTPResponse.new('1.1', '404', 'okay')
+        end
+      end
+    end
+
+    it 'has issues' do
+      check.run
+      expect(check.issues.size).to eq(1)
+    end
+  end
+
+  context 'redirect' do
+    let(:check) do
+      Nanoc::Checking::Checks::ExternalLinks.create(site).tap do |c|
+        def c.request_url_once(_url)
+          @enum ||= Enumerator.new do |y|
+            y << Net::HTTPResponse.new('1.1', '302', 'look elsewhere').tap do |h|
+              h['Location'] = 'http://elsewhere.example.com/'
+            end
+            y << Net::HTTPResponse.new('1.1', '200', 'okay')
+          end
+          @enum.next
+        end
+      end
+    end
+
+    it 'has no issues' do
+      check.run
+      expect(check.issues).to be_empty
+    end
+  end
+
+  context 'redirect without location' do
+    let(:check) do
+      Nanoc::Checking::Checks::ExternalLinks.create(site).tap do |c|
+        def c.request_url_once(_url)
+          @enum ||= Enumerator.new do |y|
+            y << Net::HTTPResponse.new('1.1', '302', 'look elsewhere')
+          end
+          @enum.next
+        end
+      end
+    end
+
+    it 'has issues' do
+      check.run
+      expect(check.issues.size).to eq(1)
+      expect(check.issues.first.description)
+        .to eq('broken reference to http://example.com/x: redirection without a target location')
+    end
+  end
+end