I have inherited a large and firaly complex state machine at work.

• It has 31 possbile states to be in.
• It has the following inputs:
  • Enum: Current State (so 0 -> 30)
  • Enum: source (currently only 2 entries)
  • Boolean: Request
  • Boolean: type
  • Enum: Status (3 states)
  • Enum: Handling (3 states)
  • Boolean: Completed

The 31 States are really needed (big business process).
Breaking into seperate state machines doesnt seem feasable - each state is distinct.

I have written tests for one set of inputs (the most common set), with one test per input (all inputs constant, except for the State input):

[Subject("Application Process States")]
public class When_state_is_meeting2Requested : AppProcessBase
{

    Establish context = () =>
    {
        //Setup....

    };

    Because of = () =>
        process.Load(jas, vac);

    It Current_node_should_be_meeting2Requested = () => process.CurrentNode.ShouldBeOfType<meetingRequestedNode>();

    It Can_move_to_clientDeclined = () => Check(process, process.clientDeclined);
    It Can_move_to_meeting1Arranged = () => Check(process, process.meeting1Arranged);
    It Can_move_to_meeting2Arranged = () => Check(process, process.meeting2Arranged);
    It Can_move_to_Reject = () => Check(process, process.Reject);

    It Cannot_move_to_any_other_state = () => AllOthersFalse(process);

}

As no one is entirely sure on what the output should be for each state and set of inputs i have been starting to write tests for it, however on calculation i will need to write 4320 ( 30*2*2*2*3*3*2 ) tests for it.

Does anyone have any suggestions on how i should go about testing this?