I have got following question in an ISTQB mock exam.

Given the following State Table:

S1 S2
S2 S3 S1
S3 ES S3

Question is which are invalid state transitions, but first of all I would like to know valid ones. How should this question be interpreted? I haven't found yet any detailed solution to this.


Here is a state diagram and its corresponding state table: state-diagram


It is pretty much self-explanatory now.

'E' from state 'S2' is valid
'E' from state 'S3' is invalid

Now, the problem with your question is the table format. There is no way to guess what comes under 'F'. Also, under 'A', there are too many parameters even if we move out the first column.

When i copy the table provided in this answer and remove the intermediate blank cell spaces, I get the following:

A   B   C   D   E   F
SS  S1                  
S1  S2              
S2  S3  S1  ES
S3  ES      

As you can see, it is not possible to figure out the right answer using this.

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  • Wonderful! Thanks for showing that questions can be wrong/ badly printed at times – Deepika Fernando Dec 13 '16 at 1:41

A B C D E F SS S1 [SS->S1] S1 S2 [S1->S2] S2 S3 S1 [S2->S3 and S2->S1] S3 ES S3 [S3->ES and S3->S3] ES

state transition graph

A valid for SS->S1 B valid for S1->S2 C valid for S2->S3 D valid for S3->ES E valid for S2->S1 F valid for S3->S3(loop)

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