
Test Generation from Finite-State Models
q
0
q
i
r/u
q
j
a/w
q
k
s‘/v
q
k’
q
j’
s‘/v’
a/w
Incorrect transfer
Correct transfer
Fig. 3.17 Detecting errors using tests generated by the W-method.
the remaining input s moves the IUT to its final state q
j
or q
j
. These
two phases are shown in Figure 3.17.
When the IUT is started in its initial state, say q
0
, and excited with
test t, it consumes the string r and arrives at some state q
i
as shown in
Figure 3.17. The output generated so far by the IUT is u, where u =
O(q
0
, r). Continuing further in state q
i
, the IUT consumes symbols
in string s and arrives at state q
j
.The output generated by the IUT
while moving from state q
i
to