Java程序辅导

SED Practical Class 5 
Week 12 
 
Conformance Testing Laboratory 
                   
 
Objectives 
In this practical you will be implementing and running Chow’s conformance test. 
                     
 
Task 
 
This practical is to be undertaken by students working in pairs in Lab 2.01.  
 
1. Read the finite state machine lecture notes (see SED Readings) and particularly 
the ant maze example (10 minutes). 
2. Working with your partner develop a set of inputs P, that should lead to every 
state of the machine, and a set of inputs Z that should distinguish between every 
pair of states in the machine. (20 minutes) 
3. Use the sets P and Z to build a minimal set of test cases to cover all possible 
transfer and action errors. (10 minutes) 
4. Download the files AntGood.class, AntBroken.class and run them (Java 
AntBroken will give you instructions on how to interact with the programme). (10 
minutes) 
5. Use your minimal set of tests to analyse AntBroken, using AntGood as a correct 
oracle. (20 minutes) 
6. List the error uncovered in step 5 and classify them as action errors or transfer 
errors. (10 minutes) 
 
            
 
Further Reading 
 
Chow, Tsun. S.: Testing Software Design Modeled by Finite-State Machines IEEE Trans. 
on Software Engineering, SE-4 (3) (1978)

 
Bruegge and Dutoit, p459, State-based testing 
 
Cardell-Oliver, R: Conformance Tests for Real-Time Systems with Timed Automata 
Specifications, FACJ 12: 350-371, 2000 
 
Holzmann, G.J.: Design and Validation of Computer Protocols Prentice Hall (1991) 
 
 
 
 
An ant is trying to get out of a maze using inputs from its left and right antennae, each of which 
returns 1 if in contact with a wall and 0 otherwise. The ant is able to go forward, and turn to the 
left or the right. The ant solves the maze problem by adopting the strategy of keeping its right 
antenna to the wall. For more details and discussion see Finite State Machines Lecture Notes 
with Ant Maze example. This system can be modelled by a finite state Mealy machine as 
follows.  
 
Inputs:  00, 01, 10, 11 (representing current readings from the ant’s left and right antennae) 
  
Outputs:  FWD, TL, TLF, TRF (possible ant movements – go forward, turn left, turn left and go 
forward in the same move, turn right and go forward)  
 
States:  Lost (initial state), EorG (wall ahead), BorC (re-finding wall to the right), 
A (following the wall on the right)  
 
 
FSM Specification  
 
Source State  Input 
(from antennae)  
Output 
(ant movement)  
Destination State 
Lost  00  FWD  Lost  
Lost  01  TL  EorG  
Lost  10  TL  EorG  
Lost  11  TL  EorG  
EorG  00  TRF  BorC  
EorG  01  TL  EorG  
EorG  10  TL  EorG  
EorG  11  TL  EorG  
BorC  00  TRF  BorC  
BorC  01  TLF  A  
BorC  10  TRF  BorC  
BorC  11  TLF  A  
A  00  TRF  BorC  
A  01  TLF  A  
A  10  TL  EorG  
A  11  TL  EorG