Software Testing Tutorial #35 - Boundary Value Analysis in Testing

Summary

This tutorial delves into Boundary Value Analysis (BVA), a critical software testing technique that complements Equivalence Partitioning (EP). The instructor uses a relatable house-building analogy to explain BVA, emphasizing the importance of testing at boundary values where software often fails. The tutorial demonstrates how to apply both techniques together to create effective test cases for maximum component coverage, highlighting their necessity for manual testers and those aspiring to excel in software testing.

Takeaways

• 😀 Boundary Value Analysis (BVA) is a software testing technique that focuses on the boundaries of input ranges and values.
• 🔍 BVA is often used in conjunction with Equivalence Partitioning (EP) to create comprehensive test cases.
• 🏠 The script uses the analogy of building a house to explain BVA, emphasizing the importance of defining boundaries before constructing the 'house' or test cases.
• 📊 Equivalence Partitioning divides the input range into valid and invalid partitions to simplify testing by reducing the number of test cases needed.
• 📈 The tutorial provides a discount example to illustrate how to apply both EP and BVA to identify test cases with maximum coverage.
• 🛑 BVA is crucial for identifying potential failures at the boundaries of input ranges, where software components are more likely to fail due to calculation and logic errors.
• 📝 The script explains how to determine the lower and upper boundary values for each partition and the importance of testing these values.
• 📉 Invalid partitions, such as purchases below $1 or above $5001, are also considered in BVA to ensure the software handles these cases correctly.
• 🔑 The tutorial emphasizes the importance of testing both within and at the boundaries of valid partitions to achieve full test coverage.
• 📚 Understanding BVA and EP is essential for manual testers and those looking to enter the field of software testing.
• 💼 The concepts of BVA and EP are valuable for explaining test design techniques during interviews for software testing roles.

Q & A

What is Boundary Value Analysis (BVA)?

Boundary Value Analysis is a black box software testing technique that focuses on testing inputs at the boundaries of an input domain. It is often used in conjunction with Equivalence Partitioning (EP) to ensure maximum test coverage.

How does Boundary Value Analysis complement Equivalence Partitioning?

Equivalence Partitioning divides the input data into groups that are expected to behave similarly, while Boundary Value Analysis focuses on the edge values of these partitions. By combining both techniques, testers can ensure that both the normal and edge cases are thoroughly tested.

Can you provide an example of how to apply Boundary Value Analysis in a real-world scenario?

The script uses the example of building a house on a plot of land. Just as you define the boundaries of your land before construction, in BVA, you define the boundaries of input values and then test within those boundaries to ensure the software behaves as expected.

What is the significance of testing at boundary values in software testing?

Software components often fail at boundary values due to calculation and logic errors. Testing at these points helps identify potential issues that might not be caught with random testing within the range of valid inputs.

How does the script illustrate the concept of valid and invalid partitions in the context of a discount example?

The script uses a discount example where different discount rates apply based on the amount spent. Valid partitions are the ranges of spending that qualify for specific discounts, while invalid partitions are values outside these ranges, such as amounts less than $1 or more than $5001, which are not allowed to purchase.

What are the boundary values for the 5% discount partition in the given example?

For the 5% discount partition, the lower boundary value is $1.00, and the upper boundary value is $100.99, assuming the software does not round up to the next dollar.

How many boundary values are identified in the script for the discount example?

The script identifies 10 boundary values across different discount partitions, including both valid and invalid boundaries.

Why is it important to test values between the boundary values in addition to the boundaries themselves?

Testing values between boundary values ensures that the software behaves correctly within the entire range of valid inputs, not just at the edges. This helps achieve comprehensive test coverage and identify any potential issues that could arise within the input range.

What is the purpose of combining Equivalence Partitioning and Boundary Value Analysis in software testing?

Combining these two techniques helps create a structured approach to testing that covers both typical and edge case scenarios. This method reduces the chance of missing critical test cases and provides clarity in test case design.

How does understanding BVA and EP help someone get into a software testing job?

Understanding BVA and EP demonstrates knowledge of fundamental black box testing techniques, which are essential for manual testers and those looking to enter the field of software testing. Being able to explain and apply these concepts can make a candidate more attractive to potential employers.

Outlines

00:00

📘 Introduction to Boundary Value Analysis (BVA)

The script introduces the concept of Boundary Value Analysis (BVA) in software testing, following up on the previous tutorial on Equivalence Partitioning (EP). It uses the same example of a discount system to demonstrate how to apply both EP and BVA together for effective test case design. The example involves a website offering different discounts based on the amount spent, with valid partitions for discounts and invalid partitions for purchases below $1 or above $5001. The script explains the importance of understanding both valid and invalid boundaries to ensure comprehensive testing of the software component.

05:01

🏗️ Applying BVA with Equivalence Partitioning

This paragraph delves into the practical application of Boundary Value Analysis in conjunction with Equivalence Partitioning. It uses an analogy of building a house on a plot of land to explain the concept of defining boundaries and then constructing within those boundaries. The script translates this analogy to software testing, where boundaries are identified for each partition, and test cases are designed accordingly. It discusses how to determine lower and higher boundary values for different discount rates, emphasizing the importance of testing at these boundary values due to the likelihood of software failures at these points.

10:02

🔍 Importance of Boundary Value Analysis in Software Testing

The final paragraph emphasizes the significance of Boundary Value Analysis in identifying potential failures in software components, particularly at boundary values where calculations and logic are prone to errors. It outlines the process of selecting test cases that cover both boundary and in-between values within valid partitions, as well as invalid partitions, to ensure thorough testing. The script concludes by highlighting the benefits of using BVA and EP together for comprehensive test coverage and provides advice for those looking to enter the field of software testing, encouraging them to understand these techniques for better test design and job prospects.

Keywords

💡Boundary Value Analysis (BVA)

Boundary Value Analysis is a black box testing design technique used to derive test cases. It focuses on the boundaries of input values or partitions, where software is more likely to fail. In the video, BVA is explained as a method to identify edge cases and is used in conjunction with Equivalence Partitioning to ensure comprehensive test coverage. The script uses the analogy of building a house to explain how defining boundaries is crucial for constructing test cases.

💡Equivalence Partitioning (EP)

Equivalence Partitioning is another black box testing technique that divides the input data of a software system into groups of similar data from which test cases can be derived. The video emphasizes the importance of using EP to categorize the input data into valid and invalid partitions, which are then used alongside BVA to create effective test cases, as demonstrated with the discount example.

💡Test Cases

Test cases are specific scenarios or sets of conditions under which a software system is tested to determine whether it behaves as expected. The script explains how to create test cases using BVA and EP by identifying boundary values and partitioning the input space, ensuring that the test cases cover all possible scenarios, including edge cases.

💡Discount Example

The discount example in the script is a practical scenario used to illustrate the application of BVA and EP. It describes a situation where different discount percentages apply based on the amount spent, and the script shows how to partition the input values and identify boundary values to create test cases for maximum coverage.

💡Boundary Values

Boundary values are the limits of the input ranges defined during BVA. They are critical points where errors are more likely to occur. The script explains how to identify lower and upper boundary values for each partition and how these values are used to create test cases that probe the software's response at its limits.

💡Input Partitions

Input partitions are subsets of input data that are grouped based on equivalence criteria. In the context of the video, input partitions are created using EP, where the script discusses how to categorize purchase amounts into partitions that receive different discount rates, which are then used for BVA.

💡Software Testing

Software testing is the process of evaluating a software system to detect any defects or to certify that it complies with specified requirements. The video is a tutorial on software testing techniques, specifically BVA and EP, and how they are essential for a tester to ensure the quality of software.

💡Coverage

Coverage in the context of software testing refers to the extent to which the software's functionality is tested. The script emphasizes the importance of achieving maximum coverage by using BVA and EP to create test cases that explore all partitions and boundary values, thus reducing the likelihood of missing critical test scenarios.

💡Black Box Testing

Black box testing is a method of software testing that focuses on the functionality of the software without considering the internal structure or code. The video discusses BVA and EP as black box techniques, which are used to design test cases based on the software's input and output behavior, as illustrated with the discount example.

💡Invalid Partitions

Invalid partitions are groups of input data that do not meet the software's requirements and are expected to be rejected or handled in a specific way. The script uses the example of purchase amounts below one dollar and above 5001 dollars, which are defined as invalid partitions and are tested to ensure the software correctly handles these cases.

💡Test Design Techniques

Test design techniques are methods used to create test cases that effectively evaluate the software. The video presents BVA and EP as essential test design techniques that, when used together, provide a structured approach to identifying and testing all relevant scenarios, including boundary conditions.

Highlights

Introduction to Boundary Value Analysis (BVA) in software testing.

The relationship between Equivalence Partitioning (EP) and BVA.

Using the same example from the previous tutorial to explain BVA.

Explanation of valid and invalid partitions in the context of a discount example.

How to apply EP and BVA together to create effective test cases.

The concept of partitioning discounts and purchase amounts in EP.

The analogy of building a house to explain the concept of BVA.

Defining boundaries for test cases in software testing, similar to land boundaries for a house.

The process of identifying boundary values within equivalence partitions.

Importance of testing boundary values due to higher failure rates at these points.

How to derive test cases from boundary values and partitions.

The significance of not rounding values in certain software modules.

Detailed explanation of boundary values for different discount percentages.

The approach to design test cases with predefined values for maximum coverage.

Advantages of using EP and BVA over random testing for software components.

The necessity of testing both boundary and in-between values for comprehensive coverage.

Practical application of BVA and EP in manual testing and software testing interviews.

Encouragement for viewers to ask questions for further clarification.

Transcripts

hello everyone welcome again in the

software testing tutorial

we are going to understand what is

boundary value analysis

so in the last tutorial we have

understood about equivalence

partitioning or

ep in short now we will understand about

bva

or boundary value analysis equivalence

partitioning and boundary value

analysis go hand in hand so i'll

continue with the same example

that i explained in the last tutorial

and i'll show you

how you can apply equivalence

partitioning and boundary value analysis

together

to come up with the best test cases to

get the maximum coverage for the

component

that you are going to test all right so

this is the discount

example that we have took in the last

tutorial

so these you know were the four valid

partition so i'll just write valid

and here it is invalid above 5001

should be not allowed to purchase right

so these are the discount purchases

that a particular website uh is offering

and we are say for example going to test

it so in equivalence partitioning what

we have done is we have partitioned

the discounts uh

and the amount that need to be purchased

in a particular partition right so for

example up to 100

from one two hundred dollars the

discount percentage should be five

percent

hundred and one to two hundred dollars

should be ten percent right

so this is what we have done to divide

the discount percentage into equivalence

partitions

and then we had invalid partition

because anything less than point

less than one dollar should should not

be allowed to purchase

and anything above five thousand one

dollar should shouldn't be

you know allowed uh the purchase

shouldn't be allowed in that case

so now if we talk about the boundary

value analysis

i'll come up with the example of the

boundary so

very raw example say for example

you are let me remove this as of now

i'll make it again

say for example you are building a house

okay

now when you are building a house you

have a piece of land

and the piece of land will have the

length and

breadth okay so this is length and this

is breadth

right so usually you know this is say

for example your frontage and say for

example this is of 10 meters

and this is of 20 meters depth okay

now when you're building the house you

basically first thing you do

is you see the map and you

define the boundaries of your

land or the piece of land that you have

bought to build the house right

so in this case you will say okay this

is you know this is my

you know boundary on the map 0 to 10

meters

okay this is what my frontage is and

then you know again from here

0 to 20 meter this is my depth is and

you define

the boundary once you define the

boundary of your

piece of land then you start you know

you you

have the boundary build and usually you

then you know define

all the plan and you start building your

house within that boundary

so boundary value analysis is no

different from what this example is

we have the boundaries so we define the

boundaries

and then within those boundaries what we

can do

as part of you know defining the test

cases we

define those test cases so in case of

building the house we define the

boundaries and then we build the house

okay we build house we build rooms

everything within the boundary

and in terms of boundary value analysis

and software we define the boundaries

and then we come up with the test cases

within those boundaries okay

so as part of equivalence partitioning

we have already defined

you know the partitions or

plots in this case or the piece of land

that everyone is going to build

okay say for example this is the

partition

i'll explain this with the same analogy

so this is say for example my plot this

is my niche's plot

say this is somebody else's so say ram's

plot

this is shiva's plot

okay and

this is for example tony's plot

right so now i know my plots boundary so

what i know is i know that this boundary

or

this plot or this partition

is mine and this partition is valid from

0 from 1 200 right so when we talk about

e-commerce thing

we have the values that are accepted in

this particular

partition so one dollar is what i should

be starting with

and up to say for example 100 or

whatever the end boundary

is i should be testing

this partition with those boundary okay

so first thing is in boundary value

analysis to

analyze the partition that you have done

in equivalence partition and get the

boundaries

okay so in this case the lower boundary

will be 100 uh one dollar okay

so we'll be starting with the lower

boundary as we have

understood in the plot example that if

the frontage is

10 meters so i'll start from 0 to 10

meters and i'll mark that

and then i'll go depth and start with

that so in this

five percent discount thing one dollar

is the

lower boundary and then

if say for example this particular

software or this particular module

accepts up to two decimal places and

doesn't

round those values so for example it

accepts 100.99

and doesn't round 0.99 to 101

okay it doesn't do that then the highest

boundary

of the purchase should be 100.99

okay so 100.99

is what the highest purchase amount

should be in this particular partition

that should still

be applicable for five percent discount

because as soon as

this changes to 101 dollar

right as soon as this changes to 101

dollar

this becomes the boundary lower boundary

of 10 percent discount

okay so that's how you analyze each of

the equivalence partition

and get the boundary values so in this

case the lower boundary value is 101

the higher boundary value is 200.99

because we have already you know assumed

that 0.99 is not getting rounded

to one dollar okay so this should still

be applicable

for 10 discount so we are getting the

lower boundary the higher boundary

same case as we had in the plot lower

boundary higher boundary for length and

breadth so that we can define

our plot and start building the house so

we are here we are defining

the lower boundary and higher boundary

so that

we can define what our boundaries are

what

this particular partitions boundary are

so that we can pick the values and start

defining which values we are going to

use in our test cases

okay here in the 20

discount the lower boundary is 201

and the higher boundary is again 500.99

in the 25 percent it is 501

the lower boundary and the higher

boundary is

5000.99

okay and then 5001

as soon as it reaches 5001 purchase

amount it is again

invalid purchase amount and it shouldn't

be allowed

or customer shouldn't be allowed to

purchase or make the purchase of that

particular amount right so you can

consider here that these are you know

sort of plots that we have

understood in the plot analogy and then

come up with the lower and higher

boundaries

and then design your test case so let me

move this and

now here in the invalid

lower invalid boundary we have this 0.99

anyways okay so now we have got these

equivalence partition which is we have

understood in the previous tutorial so

we have partitioned these discount

based on the values that are accepted in

the partitions

and we have also got the boundary so we

have got the boundary of 0.99

then we have got the boundary lower

boundary of five percent discount which

is one dollar

then 100.99 then 101

200.99 then

201 500.99

501 and 5000.99

right and then 5001

as soon as a person wants to purchase 5

000 one dollar

amount or want to spend on that

particular website it shouldn't

allow that right so now if you see

that instead of doing the random testing

when we use equivalence partition and

boundary value analysis together

we have come up with very predefined

test cases or the data that we use that

we need to use in our test cases from

each of the partitions along with the

boundary values

right why do we need to do the boundary

value analysis and testing because

the software components most of the time

you know because of the calculation and

logic

they are they tend to fail more at the

boundary values

okay so it is very necessary that we

test the

value in between along with all the

boundary values of the valid and invalid

partitions

okay so that is why now we have the

partitions so we can easily come up with

1 2 3 4 5 6 7

8 9 10 boundary values so we'll use

these

as our test cases okay along with

some values between these

valid partitions right so for example

you pick

one or two values from one two hundred

so you can pick you know ten dollars you

can pick

seventy dollars it will still be

considered as five percent discount

you pick one or two values from each of

these partitions

even if you pick just one should still

be fine and then pick all the boundary

values

and that is what will be required

to give you a complete coverage of

this particular component right so

rather than doing

random pick and choose and you know

start doing testing from one dollar to

50 to

you know 150 and then 200 and not

knowing the partitions and boundary

it's better to design your test cases

do the equivalence partition do the

boundary value analysis

and then use these values in

your test case or design your test case

which will give you a lot better

coverage

and clarity in terms of defining the

test cases and there will be very

minimal chance of

missing any of the boundary values or

equivalence partitions okay

so that is all for this particular

tutorial

on boundary value analysis boundary

value analysis goes hand in hand with

equivalence partition

so you have to apply both together to

get the

maximum benefit and these are the two

test design black box test design

techniques that

are must for you to understand

uh in terms of you know manual tester or

person who wants to get into software

testing and even in terms of

understanding and explaining to any

software testing interviewer

okay so if you explain all these

concepts with these sort of examples

and understand these in detail you will

be definitely be able to get into

software testing job very easily

so hope this was helpful and clear if

you want

you know any more detail or you have any

queries please do comment in the comment

section below

and i'll get back to you so that's all

for this tutorial

thank you very much for watching