2 Why We Need Model-Based Testing

98 Exploring and Analyzing Finite Model Programs
Messages
TitlesOnly
ByMostRecent
Table 6.2. Newsreader true FSM: state transition table
Current state Action Next state
Topics, X, X SelectMessages Messages, –, –
Messages, X, X SelectTopics Topics, –, –
Topics, WithText, X ShowTitles –, TitlesOnly, –
Topics, TitlesOnly, X ShowText –, WithText, –
Topics, TitlesOnly, ByMostRecent SortByFirst –, –, ByFirst
Topics, TitlesOnly, ByFirst SortByMostRecent –, –, ByMostRecent
X indicates “don’t care” values in the current state, where any value will do
– indicates “don’t change” values in the next state, where the value is the same as in the current state.
Values shown are for the variables in this order: page, style, sort
The initial state is Topics, WithText, ByMostRecent
SelectMessages()
Topics
TitlesOnly
ByMostRecent
SelectTopics() ShowText() ShowTitles()
Topics
WithText
ByMostRecent
SelectMessages()SelectTopics()
Messages
WithText
ByMostRecent
SortByFirst()
ShowText()
Topics
WithText
ByFirst
Messages
WithText
ByFirst
Topics
TitlesOnly
ByFirst
ShowTitles()
SelectMessages() SelectTopics()
Figure 6.2. Newsreader true FSM: state transition diagram.
SortByMostRecent()
SelectMessages() SelectTopics()
Messages
TitlesOnly
ByFirst
Compare the state transition table (Table 6.2) to the model program (Chapter 5,
Figures 5.4 and 5.5). Notice that there is a row in the table for each action in the
program, and notice how the current state and the next state entries in the table
correspond to the enabling conditions and action methods in the program, respectively.
In fact, we wrote the state transition table first, and coded the model program
from it. This is often an effective way to design and code a model program that has
a small number of states and actions.
more free ebooks download links at:
http://www.ebook-x.com