ISTQB FOUNDATION 4.0 | Tutorial 33 | State Transition Testing | Test Case Design Techniques | CTFL

Summary

This tutorial delves into state transition testing, a blackbox technique for analyzing software requirements with control flows or state definitions. It emphasizes the use of state transition diagrams (STDs) to visualize system states and valid transitions, excluding invalid ones. The instructor illustrates how to identify valid and invalid transitions to derive comprehensive test cases, using examples like a bank card PIN entry system and the states of water. The video aims to prepare viewers for ISTQB Foundation level certification, focusing on understanding the technique rather than memorization, with sample exam questions to solidify the concepts.

Takeaways

• 📚 The tutorial is focused on ISTQB Foundation level certification, specifically chapter 4.2 on blackbox test techniques.
• 🔍 The last technique discussed in the chapter is State Transition Testing, which is used for requirements with control flow or defined states and transitions.
• 🔑 State Transition Testing is applicable for transactional or functional requirements where actions lead to the next state of an application.
• 💡 An example given is accessing an account which involves swiping a card and entering a PIN, with different outcomes based on the number of incorrect attempts.
• 📈 Straight Transition Testing is a technique used to visually represent requirements and derive the minimum number of test cases.
• 📊 State Transition Diagram (STD) is a key tool in State Transition Testing, showing all valid transitions between states without invalid transitions.
• 🚫 Invalid transitions are not displayed in the STD, but they can be identified by missing pairs of transitions between states.
• 🔑 The technique involves identifying valid and invalid transitions to ensure full test coverage, including both valid and invalid test cases.
• 📝 At the Foundation level, exam questions will provide diagrams and ask about valid and invalid test cases based on those diagrams.
• 📑 The tutorial also provides examples of exam questions to illustrate what candidates can expect and how to approach them.
• 🎓 The importance of understanding the concepts behind State Transition Testing is emphasized, as it is not just for passing the exam but also for practical application.

Q & A

What is the main focus of the tutorial in the provided script?

The tutorial focuses on the ISTQB Foundation level certification, specifically discussing state transition testing, which is a blackbox test technique used to analyze requirements with control flow or state transitions.

What is state transition testing?

State transition testing is a technique used to exhibit the various states of a scenario or system and display the possible transitions between them. It is typically represented using a state transition diagram (STD), which shows all valid transitions and helps in deriving test cases.

What is a state transition diagram (STD)?

A state transition diagram (STD) is a pictorial representation that shows the various states of a system or scenario and the valid transitions between them. It does not display invalid transitions, which are identified by missing pairs of transitions between states.

How are invalid transitions identified in state transition testing?

Invalid transitions are identified by looking for missing pairs of transitions between two states in the STD. If a transition is not represented in the diagram, it is considered invalid and is not part of the system's behavior.

What is the purpose of using straight transition testing?

Straight transition testing is used to understand and deflect the requirements into a pictorial way, which helps in deriving the minimum number of test cases that cover both valid and invalid transitions.

Can you provide an example of state transition testing from the script?

An example given in the script is an ATM machine where entering a correct PIN on the first attempt takes you to the main menu, while incorrect attempts allow for two more tries, after which the card is rejected and further access is denied.

What is the significance of valid and invalid test cases in state transition testing?

Valid test cases ensure that the system behaves as expected for all possible transitions, while invalid test cases verify that the system correctly handles transitions that should not occur, thus ensuring the system's robustness and reliability.

How does the tutorial suggest approaching exam questions related to state transition testing?

The tutorial suggests that exam questions will provide a state transition diagram, and candidates should read the diagram to identify valid and invalid transitions and answer questions based on that information.

What are some of the characteristics of state transition testing discussed in the tutorial?

Some characteristics discussed include the use of an STD to represent valid transitions, the identification of invalid transitions by missing pairs, and the application of this technique to derive comprehensive test cases.

How does the tutorial explain the process of deriving test cases from a state transition diagram?

The tutorial explains that by examining the STD and identifying all valid transitions (represented by arrows) and invalid transitions (missing pairs of arrows), one can derive a comprehensive set of test cases that cover all possible scenarios.

What is the difference between state transition testing at the Foundation level and the advanced level, as mentioned in the tutorial?

At the Foundation level, candidates are expected to interpret given diagrams and answer questions about valid and invalid transitions. At the advanced level, candidates may be asked to draw the diagrams themselves and then derive the number of test cases.

Outlines

00:00

📚 Introduction to State Transition Testing

This paragraph introduces the concept of state transition testing, a blackbox testing technique used for analyzing software requirements with control flow or state definitions. It explains that this technique is particularly useful for applications where actions can lead to different states, such as a banking application requiring a card swipe and PIN entry. The paragraph uses the example of a PIN entry system to illustrate how state transition testing works, emphasizing the importance of understanding the transitions between states and the creation of test cases based on valid and invalid transitions. The technique of straight transition testing is mentioned as a method to visualize requirements and derive the minimum number of test cases.

05:01

🔍 Characteristics and Techniques of State Transition Testing

The second paragraph delves into the characteristics of state transition testing, focusing on the use of state transition diagrams (STDs) to represent the various states of a system and the transitions between them. It clarifies that STDs only show valid transitions, excluding invalid ones, and discusses how to identify invalid transitions by looking for missing pairs in the diagram. The paragraph provides a hypothetical example with three states (S1, S2, S3) to demonstrate how to determine valid and invalid transitions, resulting in a total of six test cases, four valid and two invalid. It also touches on the expectations of the ISTQB Foundation level certification exam, which involves reading and interpreting diagrams rather than creating them.

10:03

📝 Sample Exam Questions and Understanding State Transition Testing

The final paragraph presents sample exam questions to illustrate how state transition testing concepts might be applied in a real-time scenario. It uses the analogy of a water cycle to explain the technique further and then discusses how to identify valid and invalid test cases based on a given state transition diagram. The paragraph emphasizes the importance of understanding the technique and its application in deriving test cases, rather than merely memorizing for an exam. It also mentions that while the Foundation level exam will not require drawing diagrams, the advanced level will, and encourages viewers to grasp the underlying concepts for practical application.

Keywords

💡ISTQB Foundation Level Certification

ISTQB Foundation Level Certification is an international qualification for software testers, indicating a fundamental understanding of software testing principles and practices. In the video, this certification serves as the context for discussing test analysis and design techniques, emphasizing the importance of foundational knowledge for those pursuing a career in software testing.

💡Test Analysis and Design

Test analysis and design is the process of examining the software requirements and designing test cases to ensure the software meets those requirements. The video focuses on this process, particularly on blackbox testing techniques, which are methods used to test software functionality without knowledge of its internal workings.

💡Blackbox Test Techniques

Blackbox test techniques are a set of strategies used to test software where the tester does not need to understand the internal code or structure of the application. The video script discusses one such technique, state transition testing, as part of the broader category of blackbox testing methods.

💡State Transition Testing

State transition testing is a blackbox testing technique used to verify that an application correctly transitions between different states in response to user inputs or other stimuli. The script uses the example of a bank card PIN entry system to illustrate how this technique can be applied to test the transitions between states like correct PIN entry, incorrect attempts, and card rejection.

💡Control Flow

Control flow refers to the order in which individual statements, instructions, or function calls of an algorithm are executed. In the context of state transition testing, control flow is important for defining the transitions between different states within a system, as discussed in the video.

💡State Transition Diagram (STD)

A State Transition Diagram (STD) is a graphical representation used to illustrate the various states of a system and the transitions between them. The video explains that STDs are a key tool in state transition testing, helping testers visualize and understand the valid transitions that should occur within the software being tested.

💡Valid Transitions

Valid transitions are the permissible movements from one state to another within a system, as defined by the requirements. The video script emphasizes the importance of identifying valid transitions in an STD to ensure that test cases cover all possible correct behaviors of the software.

💡Invalid Transitions

Invalid transitions are movements between states that should not occur according to the system's requirements. The video uses the concept of invalid transitions to explain how testers can identify potential edge cases and ensure that the software behaves correctly even when unexpected inputs or actions are performed.

💡Straight Transition Testing

Straight transition testing is a specific approach within state transition testing that focuses on identifying and testing the direct transitions between states. The script mentions this technique as a way to derive the minimum number of test cases needed to cover all valid and invalid transitions.

💡Test Cases

Test cases are sets of conditions or variables under which a tester evaluates a software's behavior to determine if it is correct. The video script discusses how to derive test cases from state transition diagrams, emphasizing the need to cover both valid and invalid transitions to ensure comprehensive testing.

💡Pictorial Representation

Pictorial representation in the context of the video refers to the visual depiction of concepts, such as state transition diagrams, to aid understanding and analysis. The script uses the term to describe how visual tools can help testers to better comprehend the system's behavior and design effective test cases.

Highlights

Introduction to ISTQB Foundation Level Certification tutorial focusing on Test Analysis and Design.

Exploring Blackbox Test Techniques, specifically State Transition Testing.

Understanding State Transition Testing through the context of control flow and state transitions in requirements.

The importance of pictorial representation for requirements using State Transition Diagrams (STD).

Explanation of how to identify valid and invalid transitions in a State Transition Diagram.

The significance of not displaying invalid transitions in STD for maintaining system behavior integrity.

Technique of Straight Transition Testing for deriving minimum number of test cases.

Illustration of State Transition Testing with a real-world example of a bank account access system.

Detailed walkthrough of a hypothetical State Transition Diagram with three states, S1, S2, and S3.

Identification of valid and invalid transitions in the example diagram and their implications for testing.

Explanation of how missing transitions in the diagram indicate invalid test cases.

Foundation Level examination expectations regarding reading and interpreting State Transition Diagrams.

Sample exam questions to demonstrate the application of State Transition Testing in a testing scenario.

Discussion on how to approach exam questions involving identifying valid and invalid test cases from a diagram.

Use of a water state transition example to clarify the concept of valid and invalid transitions.

The importance of understanding the technique's practical application beyond just passing the exam.

Encouragement for continuous learning and application of the State Transition Testing technique.

Transcripts

Hello friends and greetings for the day

welcome back to another tutorial on

istqb Foundation level certification we

are in chapter 4 talking about test

analysis and design and continuing ahead

with our same segment that is 4.2

blackbox test techniques and as a part

of today's tutorial we'll be talking

about the last technique under this

category that is State transition

testing

well when it comes to the state

transition testing of course this is one

of its kind again just like decision

table testing here we talk about the

requirements which has any sort of

control flow involved or have a

definition between the different states

and the transitions possible so mainly

the requirements can be defined in terms

of transactional way or functional way

where uh an action can be taken to the

next state of the application where

there are only possible ways to reach

out a point in simple words if I have to

say for example in order to access your

account you will have to swipe in your

card enter the pin but entering the pin

could be a little tricky thing right you

can enter the pin right in very first

attempt and you'll be taken to the main

menu option if in case your uh first pin

attempt is wrong the loop will continue

there and you will be allowed to do two

more attempts uh if in case wrong and

third attempt it will just reject your

card and at the same time you will not

be able to continue further so in this

case to understand and deflect this

requirement into a pictorial way and

then derive the minimum number of test

cases we make use of a technique called

as straight transition testing so I do

understand again theoretically it could

be very difficult to make out things but

of course when it comes to the reality

with some examples it would make more

sense so yes let's quickly have a look

on what state transition testing is

trying to let us know about its

characteristics and the technique and

let's see how the sample exam question

questions would look like and what we

have to answer so the very first thing

here to talk about State transition

testing is it basically exhibits the

various states of a scenario or system

and displays the possible transitions

between them now the most important

thing here to understand is that state

transition testing is done with help of

State transition diagram which is

basically a pictorial representation and

it displays the various states of the

system or a scenario and only the

possible transitions between them the

reason when we say possible transitions

only is just because the invalid

transitions should not be displayed

because if it is displayed it becomes

valid right let's have a look again so

when we talk about the state transition

diagram that's what is the exhibition of

this pictorial representation however

the technique is called as state

transition testing now an STD certainly

shows all valid transitions only so it

does not represent any invalid

transition however there is a way to

figure out what are the invalid

transitions so that you can derive full

coverage that is valid plus invalid test

cases right so how to do that so in case

when we talk about the STD it consists

of a pair of transition between two

states just like in the diagram below so

if you see this is just a hypothetical

example uh we have three different

states S1 S2 S3 now in this case S1 uh I

can go from S1 to S2 S2 to S3 and same

way I can come back from S3 to S2 and S2

to S1 so there are four transitions on

the picture right here and uh four of

them are valid the all four a b c d all

the four are valid here now in this case

we totally understand that the there are

four transitions which are actually

possible as per the given scenario you

may certainly have a question that why

I'm not going from S1 to S3 that's also

possible no that's your prediction you

have to go as for the requirement if

requirement says the user should not be

able to go from S1 to S3 directly then

that becomes invalid for you that's the

behavior right you are still in blackbox

testing techniques so in this case

that's how you identify that what are my

invalid test cases but to make it more

technical from the require technique

point of view of course the technique

says uh STD should consist of pair of

transition between any two states so S1

to S2 you can see there is a pair like a

and d so it goes S1 to S2 S2 to S1 same

way between S2 and S3 you have pair of

transitions onward and return but

between S1 and S3 the pair is missing

and that's how you identify the number

of invalid test cases so if the pair is

missing between two sites then the

missing transition or transitions is or

are called as invalid transitions so

it's not necessary that both the

transitions may be missing in all the

cases sometimes just one will be missing

one will be there so only the missing

transitions are referred to as invalid

valid so in our below example the

diagram here the S1 to S2 and S3 a b c d

are four valid and two invalid because

S1 to S3 and S3 to S1 is not picturized

here imagining or understanding us that

it is invalid so in that context we have

six test cases and U four valid two

invalid however that's not what they

will be asking you to do in the

examination at Foundation level at

Foundation level they expect you to read

the diagram and based on that pick up

the right options what they ask you

about so they can ask you questions

about the test cases they can ask you

the questions about the characteristics

what we have dis displayed here on the

screen uh and discussed about that so

let's quickly take up some sample

questions from here but before that

another quick example to talk about that

what a streight tation diagram could be

all about so talking about a quick

example here so if you see uh this is

how exactly the technique works so a

street transition diagram for a water is

being considered and again I'm not not

talking about literally something in

different conditions you may come up and

say that oh you know we can talk about

dry ice and that can go to Vapors

directly so let's keep it simple and

static because we talking about

techniques not talking about how to test

water and dry ice okay so taking that

into account if you see ice uh I can

heat it and get the water then water I

can boil it and I get it the vapor a

vapor I can condensate and get water

back and if I freeze water I get get ice

back but in this case again the four

valid transitions are only possible the

other two that is ice to vapor and Vapor

to ice in normal conditions are not at

all possible Right in that context we

don't draw that's the reason I have just

pictorially presented in a black color

bigger arrows just to say that hey these

are not actually there but just to

display in order to talk about I'm

presenting it okay so it's that these

are just two invalid uh test cases and

they generally do not get displayed I

displayed because I wanted to talk about

it okay so these two are invalid and a b

c d are the valid transition however we

draw a table like this and that's how we

get our test cases from the scenario so

let's take some exam questions to

understand what could be expected in the

real time

scenario so right here if you notice we

got uh very first question to talk about

question says based on the given State

transition diagram of a switch which of

the following test cases is in valid now

invalid is what is the ask here and the

most important thing is you have to

follow the diagram and understand that

if something is not being drawn that

means the transition is missing between

two states those are the one which are

called as invalid so let's have a look

at the quick diagram here if you see

this is a switch diagram so I have on to

off off to on then when I turned it on

it got burnt and it became faulty switch

and the loop below the fault that is an

arrow turning around to The Fault itself

is basically a loop that means the

faulty switch will remain faulty forever

and it will never come back to any other

state so that Loop basically represents

that so I have S1 S2 S3 but with

different names so the question is which

one of this is

invalid so option A says off to on of

course that is in the diagram so it is

valid that means a user can do that on

to off is possible a user can certainly

uh turn off a switch C fault to on of

course fault to on is not displayed here

here so at any point of time based on

the given information that's a invalid T

case Okay false to on is not displayed

so it is invalid there's no return path

as for the diagram and the option D says

onto fault which is obviously written

there so it's a line representing

between on and fault so it is a valid

transition so put together the right

answer here is D sorry C that is Fault

to on is not a valid test case which

means invalid let's also look at one

more example here which would give you

double confidence to be sure that what

other types of questions can be asked so

additionally one more point to add here

that the pictures will be represented

always in the examination questions and

then they will be asking you questions

so do not forget that you have you don't

have to draw the diagram okay they will

not not ask you to draw however the same

thing will be asked to you in the

advanced level in advanced level they

will ask you to draw the diagram and

then derive the number of test cases but

now they will just ask you what is valid

what is invalid at this point of time so

let's quickly look at the next one and

the next question here is talking about

similar thing but with different example

so given the following straight

transition table which of the test cases

below will cover the following series of

State transitions so series is given to

you they want you to go through S1 s0 S1

S2 s0 again so if you look at the

diagram we have s0 S1 S2 and we have

transitions named there that is a b c d

so they want to follow S1 to s0 then s 0

to S1 S1 to S2 and S2 to s0 so all you

have to do is pick up each of these

options ABC D and put it on the diagram

and see which one is actually fulfilling

that Series so if I look at the very

first option A says da a b c so okay

again S1 to s0 is D that's true s0 to S1

is a S1 to S2 is B and S2 to s0 is C

which is absolutely right but let's look

at the other options AB C D no AB is

correct s0 to S1 S1 to S2 but that's not

what they are asking for okay um C they

say d a which is also possible but

that's not what they're asking because

their Series has been clearly defined

they want S1 to s0 S1 s0 to S1 and then

S1 to S2 and after that S2 to s0 as well

so just daab alone will not do it you

need the C as well okay and same way

with the option d a b c this is also

possible as for the diagram but that's

not the ask so it's very very important

for you to understand what exactly are

they asking you and more importantly you

need to understand what is the technique

all about right what a picture basically

defines what these diagrams basically

represent and how this adds value Al

together towards preparing minimum

number of test cases please do not try

to do this mathematically try to

understand the concepts because you

don't just have to pass the exam you

have to apply and understand this

technique that why are we even using

this as a technique right so that should

make sense at the end of the day so

that's all from this particular tutorial

team should you have anything else feel

free to comment below I'm always there

to address your queries and answer them

well till then keep learning keep

exploring keep understanding the context

thanks for watching the video team and

happy

[Music]

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