Lecture 8-Input space partitioning

Question 1

What are 4 characteristics of input domain?

Answer 1

-Even for small programs, input domain is so large that might be infinite
-Input PARAMETERS define scope of input DOMAIN
-Domain for each input parameter is partitioned into regions
-At least one value is chosen from each region

Question 2

What is the input domain?

Answer 2

It consists of all possible inputs that could be take by the program.

Question 3

What is the test selection problem(ideally & in practice) ?

Answer 3

Ideally : To select a subset T of the input domain so that the execution of T will reveal ALL ERRORS.

In practice: To select a subset T within the budget so it reveals as many errors as possible.

Question 4

What is partitioning?

Answer 4

It defines a set of equivalent classes , or blocks. –> all the members in an equivalence class contribute to error detection in the same way.

Question 5

What is a partition usually based on?

Answer 5

On a certain characteristic:
-if a list of integer is sorted or not
-if a list allows duplicates or not

Question 6

What do we do in partitioning ?

Answer 6

1.Partition the input domain into a relatively small number of groups.
2.Select one representative from each group.

Question 7

What are the 2 properties of partitioning?

Answer 7

Completeness:
-The partition must cover the entire domain.
Disjointness:
-The blocks must not overlap.

*If neither , it means that the partitions have not been considered carefully enough.

Question 8

What are the 4 steps of Input Domain Modelling (IDM)?

Answer 8

1. Identify testable components (method, use case , entire system)
   2.Identify ALL parameters that affect the behaviour of a component
   3.Identify characteristics + create partitions for each of them.
   4.Select values from each partition + combine them to create tests.

Question 9

What are the 2 IDM approaches?

Answer 9

-Interface-Based IDM
-Functionality-Based IDM

Question 10

What is the main idea of Interface-based IDM?

Answer 10

To develop characteristics directly from INPUT PARAMETERS.

Question 11

What is the advantage (1) and disadvantages(2) of Interface-based IDM?

Answer 11

Advantage :
-relatively easy to identify characteristics.
Disadvantage:
-IDM may be incomplete –> additional characteristics needed
-Not all info reflected in interface –> may require parameters in combination

Question 12

What is the range of Interface-based IDM?

Answer 12

One class with values inside the range
Two with values outside of range.

Question 13

What is the string of Interface-based IDM?

Answer 13

AT LEAST :
-One with all legal strings
-One with all illegal strings.

Question 14

What is the enumeration of Interface-based IDM?

Answer 14

Each value in a separate class.

Question 15

What is the array of Interface-based IDM?

Answer 15

One class with all legal arrays
One with only empty array
One with arrays larger than expected size

Question 16

What is the main idea of Functionality-based IDM?

Answer 16

To develop characteristics from the FUNCTIONAL or BEHAVIOURAL view

Question 17

What is the advantages (2) and disadvantage(1) of Functionality-based IDM?

Answer 17

Advantages:
-Includes more semantic info
-No need to wait for interface to be designed
Disadvantage:
-Hard to identify characteristics, parameter values and tests

Question 18

What do preconditions do in Functionality-based IDM?

Answer 18

They explicitly separate NORMAL behaviour from EXCEPTIONAL behaviour.

Ex: method needs a parameter to be non-null

Question 19

What do postconditions do in Functionality-based IDM?

Answer 19

They indicate what kind of outputs may be produced.

Ex: if a method produces two types of outputs, then we want to select inputs so that both types of outputs are tested.

Question 20

What are the two relationships in Functionality-based IDM?

Answer 20

Relationship of variables with special values:
-zero, null, blank…

Relationships between diff parameters:
- if a method takes two object parameters x and y, we may want to check what happens if x and y point to the same object or to logically equal
objects

Question 21

What is Boundary Value Analysis?

Answer 21

A test selection technique that targets faults in applications at the BOUNDARIES of equivalence classes.