rspec/rules/S131/csharp/rule.adoc

The requirement for a final `+default+` clause is defensive programming. The clause should either take appropriate action, or contain a suitable comment as to why no action is taken. Even when the `+switch+` covers all current values of an `+enum+`, a `+default+` case should still be used because there is no guarantee that the `+enum+` won't be extended.

== Noncompliant Code Example

----
int foo = 42;
switch (foo) // Noncompliant
{
  case 0:
    Console.WriteLine("foo = 0");
    break;
  case 42:
    Console.WriteLine("foo = 42");
    break;
}
----

== Compliant Solution

----
int foo = 42;
switch (foo) // Compliant
{
  case 0:
    Console.WriteLine("foo = 0");
    break;
  case 42:
    Console.WriteLine("foo = 42");
    break;
  default:
    throw new InvalidOperationException("Unexpected value foo = " + foo);
}
----

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