Couple of changes

lib/adapters/json.coffee

@@ -23,6 +23,6 @@ class JSONAdapter
   # @return [String] result string
   #
   @stringify: ( data ) ->
-    JSON.stringify data
+    JSON.stringify data, null, "  "
 
 module.exports = JSONAdapter

lib/config-parser.coffee

@@ -15,6 +15,7 @@ class ConfigParser
   #
   constructor: ( @path ) ->
     @format = null
+    @parsed = {}
 
   # Pick config format.
   #
@@ -48,20 +49,32 @@ class ConfigParser
     adapter = require "./adapters/#{ format }"
 
     if @rawData is ""
-      @_parsed = {}
+      @parsed = {}
     else if adapter.detect @rawData
-      @_parsed = adapter.parse @rawData
+      @parsed = adapter.parse @rawData
     else
       throw new Error()
 
     @
 
-  # Parse config.
+  # Stringify and save config.
   #
-  # @return [String] stringified value
+  # @param [String] format config format
+  # @param [Function] callback
+  # @return [ConfigParser]
   #
-  stringify: ( format ) ->
-    require( "./adapters/#{ format ? @format }" ).stringify @_parsed
+  stringify: ( format, callback ) ->
+    if typeof format is "function"
+      callback = format
+      format = "json"
+
+    try
+      fs.writeFile @path, ( require( "./adapters/#{ format ? @format }" ).stringify @parsed ), "utf8", ( err ) ->
+        callback err
+    catch e
+      callback e
+
+    @
 
   # Supported formats.
   @formats: [ "json", "plist", "ini", "yaml" ]

lib/runtime-configuration.coffee

@@ -43,7 +43,7 @@ class RuntimeConfiguration
 
     iteration = ( item, done ) ->
       new rc.ConfigParser( item.file ).pick ->
-        done null, chain.push @_parsed
+        done null, chain.push @parsed
 
     # load configs
     async.forEach ( { file, idx } for own file, idx in @lookup() ), iteration, ( err ) =>
@@ -63,7 +63,48 @@ class RuntimeConfiguration
     #   new rc.Adapter( path ).pick()
     @
 
-  save: ->
+  # Save configuration.
+  #
+  # @param [String] format config format
+  # @param [Function] callback
+  # @return [RuntimeConfiguration] rc instance
+  #
+  save: ( format, callback = -> ) ->
+    if typeof format is "function"
+      callback = format
+      format = "json"
+
+    config = new rc.ConfigParser( path.join process.env.HOME, ".#{ @appName }rc" )
+    config.parsed = @config
+
+    config.stringify format, callback
+
+    @
+
+  # Property getter.
+  #
+  # @param [String] key property name
+  # @return [Object] value
+  #
+  get: ( key ) ->
+    if key? then @config[ key ] else extend( {}, @config )
+
+  # Property setter.
+  #
+  # @param [String|Object] key
+  # @param [Object] value
+  # @return [RuntimeConfiguration] rc instance
+  #
+  set: ( key, value ) ->
+    if ( not value? ) and typeof key is "object"
+      obj = key
+    else
+      obj = {}
+      obj[ key ] = value
+
+    extend on, @config, obj
+
+    @
 
   # Load env vars
   #

test/helpers.coffee

@@ -5,6 +5,9 @@ global.glob = require "glob"
 global.wrench = require( "wrench" )
 global.sinon = require "sinon"
 global.shld = require "should"
+global.plist = require "plist"
+global.yaml = require "yamljs"
+global.ini = require "ini"
 
 global.__testsRootDir = __dirname
 global.__tmpDir = path.join __dirname, ".tmp"

test/mocha.opts

@@ -4,7 +4,6 @@
 --compilers coffee:coffee-script
 --colors
 --reporter spec
---ignore-leaks
 --require should
 --require coffee-script
 --require test/helpers.coffee

test/specs/config-parser.coffee

@@ -5,6 +5,7 @@ describe "ConfigParser", ->
       @yaml = new rc.ConfigParser path.join __homepaths.yaml, ".apprc"
       @ini = new rc.ConfigParser path.join __homepaths.ini, ".apprc"
       @plist = new rc.ConfigParser path.join __homepaths.plist, ".apprc"
+      @writeable = new rc.ConfigParser path.join __tmpDir, ".apprc"
 
     after ->
       delete @suitable
@@ -48,11 +49,44 @@ describe "ConfigParser", ->
 
       it "should try to parse config", ->
         @json.parse( "json" )
-        @json._parsed.should.be.a "object"
+        @json.parsed.should.be.a "object"
 
       it "should raise an error when can't parse", ->
         ( => @plist.parse( "json" ) ).should.throw()
 
     describe "@stringify()", ->
-      it "should serialize object to appropriate format", ->
-        @json.stringify().should.be.a "string"
+      beforeEach ->
+        @write = sinon.spy fs, "writeFile"
+        @writeable.parsed.foo = "bar"
+
+        @stringify = ( format, done, callback ) =>
+          @writeable.stringify format, ( err ) =>
+            callback.apply @, @write.getCall( 0 ).args
+            done err
+
+
+      afterEach ->
+        @write.restore()
+
+        delete @write
+        delete @stringify
+
+      it "should write file", ( done ) ->
+        @stringify "json", done, ( file ) =>
+          file.should.equal path.join __tmpDir, ".apprc"
+
+      it "should serialize json properly", ( done ) ->
+        @stringify "json", done, ( file, serialized ) =>
+          JSON.parse( serialized ).should.have.property "foo", "bar"
+
+      it "should serialize ini properly", ( done ) ->
+        @stringify "ini", done, ( file, serialized ) =>
+          ini.parse( serialized ).should.have.property "foo", "bar"
+
+      it "should serialize yaml properly", ( done ) ->
+        @stringify "yaml", done, ( file, serialized ) =>
+          yaml.parse( serialized ).should.have.property "foo", "bar"
+
+      it "should serialize plist properly", ( done ) ->
+        @stringify "plist", done, ( file, serialized ) =>
+          plist.parseStringSync( serialized ).should.have.property "foo", "bar"

test/specs/runtime-configuration.coffee

@@ -101,6 +101,40 @@ describe "RuntimeConfiguration", ->
           .be.a( "object" )
           .and.have.property( "baz", "test2" )
 
+    describe "@set()", ->
+      beforeEach ( done ) ->
+        process.env.HOME = __tmpDir
+        @config = new rc.RuntimeConfiguration( "app" )
+        @config.load done
+
+      afterEach ->
+        delete @config
+
+      it "should set only one key", ->
+        @config.set "foo", "bar"
+        @config.config.should.have.property "foo", "bar"
+
+      it "should set many keys by object", ->
+        @config.set bar: "baz", baz: "foo"
+        @config.config.should.include bar: "baz", baz: "foo"
+
+    describe "@get()", ->
+      beforeEach ( done ) ->
+        process.env.HOME = __tmpDir
+        @config = new rc.RuntimeConfiguration( "app" )
+        @config.load ( err ) ->
+          @set "foo", "bar"
+          done err
+
+      afterEach ->
+        delete @config
+
+      it "should get value by key", ->
+        @config.get( "foo" ).should.equal "bar"
+
+      it "should return entire object if key not specified", ->
+        @config.get().should.be.a "object"
+
     describe "@save()", ->
       beforeEach ( done ) ->
         process.env.HOME = __tmpDir
@@ -109,14 +143,17 @@ describe "RuntimeConfiguration", ->
         @config = new rc.RuntimeConfiguration( "app" )
 
         @config.load ( err, config ) ->
-          @config.config.foo = "bar"
-          @config.save done
+          @config.foo = "bar"
+          @save done
 
       afterEach ->
+        @write.restore()
+
         delete @config
         delete @write
 
       it "should write ~/.apprc file", ->
-        call = @write.getCall( 0 ).args
+        args = @write.getCall( 0 ).args
 
-        call[ 0 ].should.equal path.join __tmpDir, ".apprc"
+        args[ 0 ].should.equal path.join __tmpDir, ".apprc"
+        JSON.parse( args[ 1 ] ).should.have.property "foo", "bar"