4a- Black box techniques

State transition testing example

1. Suppose you want to withdraw $500 from a bank ATM, you may be given cash. 2. After some time you again try to withdraw $500 but you may be refused the money (because your account balance is insufficient). 3. This refusal is because your bank account state has changed from having sufficient funds to cover withdrawal to having insufficient funds. 4. The transaction that caused your account to change its state was probably the earlier withdrawal.

Why do both EP and BVA?

1. Testing only boundaries doe snot give much confidence as we are testing just extreme values of partitions 2. It is important to test some values in between the partitions 3. Recommended that partitions should be tested separately from boundary values 4. If you want to be more thorough start with valid partition testing then invalid partitions then valid boundaries and then finally invalid boundaries

Equivalence Partitioning

1. These conditions may not always be true however testers can use better partitions and also test some more conditions within those partitions to confirm the selection of that partition is fine 2. Also known as equivalence class

Benefits of Use Case testing

1. Use case capture systems functional requirements from an end users perspective 2. Actively involve end users and stakeholders in requirement gathering process 3. Serve as the foundation for developing system test cases

Decision table testing

1. Used if different combinations of input result in different actions 2. More efficient in testing business rules 3. Provides a systematic way of stating complex business rule which makes it very helpful 4. Aids in systematic selection of effective test cases and helps in finding any ambiguities in specifications

What is use case testing

1. each use case must specify any preconditions that need to be met for the use case to work 2. Use cases must also specify post conditions that are observable results and a description of the final state of the system after the use case has been executed successfully 3. A set of use cases make up functional requirements of the system

Four basic parts of state transition model

1. the states that the software may occupy(funds/insufficient funds) 2. the transition from one state to another (all transitions are not allowed) 3. The events that cause a transition (like withdrawing money) 4. The actions that result from a transition(an error message or being given your cash)

What is a use case?

1. A description of a particular use of the system by the end user of the system 2. Are a sequence of steps that describe the interactions between the user and the software system 3. Each use case has with the software system in order to achieve a specific task

State Transition Testing

1. A state is the position or situation that a particular system is in at a given time 2. Transition describes the way in which the system moves from one state to another 3. Systems move from a state to another set based on the input applied on the system 4. Mapping these changes in states and their transitions are the basic parts of state transition testing

Equivalence Partitioning Example

1. A store in city offers different discounts depending on the purchase amount 2. If purchase is in the range of 0 dollars and 50 dollars there are no discounts 3. Purchase over $50.01 and up to $200.00 - 5% discount 4. Purchase of $200.01 and up to $500.00 - 10% discounts

What is use case testing?

1. A technique that helps us identify test cases that exercise the whole system on a transaction by transaction basis start to finish 2. Defined in terms of the end user and not the system, use case describes what the user does and what the user sees rather than what input the software system expects and what the system outputs 3. uses the business language rather than technical terms

Boundary Value Analysis

1. Any input or output value on the edge of an equivalence partition 2. Based on testing at the boundaries between partitions

Equivalence Partitioning

1. Black box test design technique 2. Can be applied at all levels of testing 2. idea behind EP is to divide or partition a group of test conditions into a set that is considered same by the software

Boundary Value Analysis

1. Black box test design technique where test case are designed by using boundary values BVA is used range checking 2. To apply BVA you need to take maximum and minimum values from valid partition together with first or last value respectively in each of the invalid partition adjacent to the valid partition

Types of black box techniques

1. Equivalence Partitioning 2. Boundary Value Analysis 3. Decision Tables 4. state transition testing 5. Use case testing

Example of using a decision table

1. Example using Loan EMI calculator to understand decision table testing 2. Loan amount or repayment term 3. empty decision table for this example will look something like this

Using decision table for test design

1. First task to design decision table is to identify the component or system which reacts according to the combination of inputs 2. Do no deal with large number of conditions al at once divide them into smaller sub sets and test one sub set at a time 3. Once the conditions for component are identified then they are put in a table listing true or false for each aspect

Equivalence Partitioning

1. Need to test just one condition from that partition as it is assumed that all the values in that partition will be treated in same way 2. If one of the value in a partition will work then we assume all the values in that partition will work 3. If one of the value in that partition fails then it is assumes that all the values in that partition will fail

Decision table testing

1. Shows different combinations of inputs with their associated outputs 2. Also known as cause and effect table 3. Made up of Conditions or inputs and Actions or Outcomes

How to create a state transition diagram

1. State 1 and state 2 boxes specify the current state of the system 2. the transition from one state to another is shown by the arrows 3. The event is the input which must be applied to achieve the required state 4. The action is the outcome of the applied input

Deriving test cases from State transition diagram

1. State table is very useful deriving test cases from state transition graph 2. State table lists all the states down one side of the table and all the events that cause transition on the top, each cell then represents state event pair

Boundary Value Analysis Example

1. Suppose you have a text field on webpage which accepts values between 1-1000 so the valid partition will be 1 - 1000 --Equivalence partitions will be like picture 2. And the boundary values will be 1, 1000 from valid partition and , 1001 from invalid partitions