Add spec for middleware

lib/html-proofer/middleware.rb

@@ -3,6 +3,16 @@
 module HTMLProofer
   class Middleware
 
+    class InvalidHtmlError < StandardError
+      def initialize(failures)
+        @failures = failures
+      end
+
+      def message
+          "HTML Validation errors (skip by adding ?SKIP_VALIDATION to URL): \n#{@failures.join("\n")}"
+      end
+    end
+
     def self.options
       @options ||= {
         type:                :file,
@@ -43,12 +53,16 @@ def call(env)
       return result if env['REQUEST_METHOD'] != 'GET'
       return result if env['QUERY_STRING'] =~ /SKIP_VALIDATION/
       return result if result.first != 200
-
-      # [@status, @headers, @response]
       body = []
       result.last.each { |e| body << e }
-      html = body.join('').lstrip
-      if HTML_SIGNATURE.any? { |sig| html.downcase.starts_with? sig.downcase }
+
+      body = body.join('')
+      begin
+        html = body.lstrip
+      rescue
+        return result # Invalid encoding; it's not gonna be html.
+      end
+      if HTML_SIGNATURE.any? { |sig| html.upcase.starts_with? sig }
         parsed = HTMLProofer::Runner.new(
           'response',
           Middleware.options
@@ -57,7 +71,7 @@ def call(env)
         )
 
         if parsed[:failures].length > 0
-          raise "HTML Validation errors (skip by adding ?SKIP_VALIDATION to URL): \n#{parsed[:failures].join("\n")}"
+          raise InvalidHtmlError.new(parsed[:failures])
         end
       end
       result

spec/html-proofer/middleware_spec.rb

@@ -0,0 +1,33 @@
+require 'spec_helper'
+
+describe 'Middleware test' do
+  let(:request) { {'REQUEST_METHOD' => 'GET'} }
+  let(:response) { File.open(response_fixture) }
+  let(:app) { Proc.new { |*args| [200, {}, response] } }
+  let(:middleware) { HTMLProofer::Middleware.new(app) }
+  subject { middleware.call(request) }
+
+  context 'with invalid HTML' do
+    let(:response_fixture) { File.join(FIXTURES_DIR, 'html', 'missing_closing_quotes.html') }
+    it 'raises an error' do
+      expect {
+        subject
+      }.to raise_error(HTMLProofer::Middleware::InvalidHtmlError)
+    end
+  end
+
+  context 'with valid HTML' do
+    let(:response_fixture) { File.join(FIXTURES_DIR, 'html', 'html5_tags.html') }
+    it 'does not raise an error' do
+      subject
+    end
+  end
+
+  context 'with non-HTML content' do
+    let(:response_fixture) { File.join(FIXTURES_DIR, 'images', 'gpl.png') }
+    it 'does not raise an error' do
+      subject
+    end
+  end
+
+end