Write JSON to file, not a Ruby Hash.

lib/theme_check/corrector.rb

@@ -34,7 +34,7 @@ def create(theme, relative_path, content)
 
     def create_default_locale_json(theme)
       theme.default_locale_json = JsonFile.new("locales/#{theme.default_locale}.default.json", theme.storage)
-      theme.default_locale_json.update_contents('{}')
+      theme.default_locale_json.update_contents({})
     end
   end
 end

lib/theme_check/json_file.rb

@@ -20,14 +20,19 @@ def parse_error
       @parser_error
     end
 
-    def update_contents(new_content = '{}')
+    def update_contents(new_content = {})
+      raise ArgumentError if new_content.is_a?(String)
       @content = new_content
     end
 
     def write
-      if source != @content
-        @storage.write(@relative_path, content)
-        @source = content
+      pretty = JSON.pretty_generate(@content)
+      if source.rstrip != pretty.rstrip
+        # Most editors add a trailing \n at the end of files. Here we
+        # try to maintain the convention.
+        eof = source.end_with?("\n") ? "\n" : ""
+        @storage.write(@relative_path, pretty + eof)
+        @source = pretty
       end
     end
 

test/json_file_test.rb

@@ -32,6 +32,15 @@ def test_parse_error_with_error
     assert_instance_of(JSON::ParserError, @json.parse_error)
   end
 
+  def test_write
+    storage = make_storage("a.json" => '{ "hello": "world" }')
+    expected = { hello: "friend" }
+    @json = ThemeCheck::JsonFile.new("a.json", storage)
+    @json.update_contents(expected)
+    @json.write
+    assert_equal(JSON.pretty_generate(expected), storage.read("a.json"))
+  end
+
   private
 
   def make_json_file(name, content)