CodeFormatter is a tool that uses Roslyn to automatically rewrite the source to follow our coding styles, which are documented here.
In order to build or run this tool you will need to have Microsoft Build Tools 2015 Preview installed. This comes as a part of Visual Studio 2015 Preview or can be installed separately from here.
In order get the usage, simply invoke the tool with no arguments:
$ .\CodeFormatter.exe
CodeFormatter <project or solution> [<rule types>] [/file:<filename>] [/nocopyright] [/c:<config1,config2> [/copyright:file]
<rule types> - Rule types to use in addition to the default ones.
Use ConvertTests to convert MSTest tests to xUnit.
<filename> - Only apply changes to files with specified name.
<configs> - Additional preprocessor configurations the formatter
should run under.
<copyright> - Specifies file containing copyright header.
We follow the same contribution process that corefx is using.