Change JsonSyntax hook to use hook messages

This simplifies this hook by changing it to not have to explicitly check
if there were any messages before returning pass/fail. It now simply
returns the messages and the framework will do the rest.

To support this, the MessageProcessor was updated to support hook
messages without line numbers. The theory is that messages without line
numbers should apply to the entire file.

Change-Id: I20f293cd0b741ad9879da9a738cc083ede1dc088
Reviewed-on: http://gerrit.causes.com/47212
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>

Author: sds

lib/overcommit/hook/pre_commit/json_syntax.rb

@@ -2,19 +2,18 @@ module Overcommit::Hook::PreCommit
   # Checks the syntax of any modified JSON files.
   class JsonSyntax < Base
     def run
-      output = []
+      messages = []
 
       applicable_files.each do |file|
         begin
           JSON.parse(IO.read(file))
         rescue JSON::ParserError => e
-          output << "#{e.message} parsing #{file}"
+          error = "#{e.message} parsing #{file}"
+          messages << Overcommit::Hook::Message.new(:error, file, nil, error)
         end
       end
 
-      return :pass if output.empty?
-
-      [:fail, output]
+      messages
     end
   end
 end

lib/overcommit/message_processor.rb

@@ -126,6 +126,9 @@ def remove_ignored_messages(messages)
     end
 
     def message_on_modified_line?(message)
+      # Message without line number assumed to apply to entire file
+      return true unless message.line
+
       @hook.modified_lines_in_file(message.file).include?(message.line)
     end
   end

spec/overcommit/hook/pre_commit/json_syntax_spec.rb

@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'json'
 
 describe Overcommit::Hook::PreCommit::JsonSyntax do
   let(:config)      { Overcommit::ConfigurationLoader.default_configuration }