Fix http with connection error (#2770)

* fix: http resource handle connection failed (ex. port is not open)
* add test case

Signed-off-by: Wing924 <weihe924stephen@gmail.com>

lib/resources/http.rb

@@ -176,9 +176,10 @@ module Inspec::Resources
         def run_curl
           return if @ran_curl
 
-          response = inspec.command(curl_command).stdout
+          cmd_result = inspec.command(curl_command)
+          response = cmd_result.stdout
           @ran_curl = true
-          return if response.nil?
+          return if response.nil? || cmd_result.exit_status != 0
 
           # strip any carriage returns to normalize output
           response.delete!("\r")

test/unit/resources/http_test.rb

@@ -160,6 +160,30 @@ describe 'Inspec::Resources::Http' do
         _(worker.response_headers['Access-Control-Max-Age']).must_equal '86400'
       end
     end
+
+    describe 'run_curl request' do
+      it 'returns nil when nil is returned' do
+        Inspec::Resources::Cmd.any_instance
+                              .stubs(:stdout)
+                              .returns(nil)
+        _(worker.send(:run_curl)).must_be_nil
+      end
+
+      it 'returns nil when failure is returned' do
+        Inspec::Resources::Cmd.any_instance
+                              .stubs(:exit_status)
+                              .returns(1)
+        _(worker.send(:run_curl)).must_be_nil
+      end
+
+      it 'returns html when html is returned' do
+        Inspec::Resources::Cmd.any_instance
+                              .stubs(:stdout)
+                              .returns("HTTP/1.1 200 OK\nDate: Tue, 03 Oct 2017 20:30:08 GMT\nExpires: -1\nCache-Control: private")
+        assert = ["Date: Tue, 03 Oct 2017 20:30:08 GMT", "Expires: -1", "Cache-Control: private"]
+        _(worker.send(:run_curl)).must_equal assert
+      end
+    end
   end
 
   describe 'Inspec::Resource::Http::Headers' do