My classes are formatted like this automatically in Visual Studio.
[Serializable] public class TestException : Exception { public TestException() : b
Unfortunately there is no such setting in the Visual Studio's built-in Options\Text Editor\C#\Formatting\New Lines dialog.
Options\Text Editor\C#\Formatting\New Lines
If you use ReSharper there is a Place constructor initializer on same line option under Code Editing\C#\Formatting Style\Line Breaks and Wrapping:
Place constructor initializer on same line
Code Editing\C#\Formatting Style\Line Breaks and Wrapping