Test Design Technique
Test design technique
• A test design technique is used to select a good set of tests from all possible tests for a given system.
• Exhaustive Testing is not possible, so we need to use Test Design Techniques in order to reduce the size
of the input.
o Exhaustive Testing is a Test approach in which the test suite comprises all combinations of input
values and preconditions.
There are two main categories of Test Design Techniques, They are:
a. Static Techniques
b. Dynamic Technique
Static Techniques:
Testing of the software documents manually or with a set of tools but without executing the Software.
Two types of static testing techniques
- Reviews (Manual Examination)
- Static Analysis (Automated Analysis)
- Reviews
Types of Reviews
a) Informal Review
b) Walkthrough
c) Technical Review
d) Inspection - Static Analysis
Static analysis tools are typically used by developers, Compilers offer some support for Static analysis,
Reviews:
Informal Review - During informal review, the work product is given to a domain expert and the feedback/comments are
reviewed by the owner/author.
Walkthrough - performed on any kind of requirements, design, or project plan and is generally moderated by the owner of the
work product. Walkthrough can be also done for training people and establishing consensus.
Technical Review - performed on any kind of requirements, design, code, or project plan and is generally moderated by the
technical lead. Technical review is a formal type of static test and done for observing whether or not the work product meets the
technical specifications/standards.
Inspection – Inspections are a formal type of review that involves checking the documents thoroughly before a meeting and is
carried out mostly by moderators. A meeting is then held to review the code and the design. Inspection meetings can be held
both physically and virtually.
Dynamic techniques
• Dynamic test design techniques involve testing by running the system under test
• In this technique, the tester provides input data to the application and executes it. This is done to verify its
different functional and non-functional requirements.
Categories of Dynamic Test Design Techniques
- Specification-based or Black-box Techniques
I. Equivalence Partitioning (EP)
II. Boundary Value Analysis (BVA)
III. Decision Table Testing
IV. State Transition Testing
V. Use Case Testing - Structure-based or White-box Techniques
I. Statement Testing and coverage
II. Decision Testing and Coverage
III. Condition Testing, Multi Condition Testing - Experience-based Techniques
I. Error Guessing
Equivalence Class Partitioning
Equivalent Class Partitioning allows you to divide set of test condition into a partition which should be
considered the same.
Your task is to pick one condition out of each partition, which covers all possible scenarios, to execute test cases.
If a condition of a partition is valid, other conditions are valid too. Likewise, if a condition in a partition is invalid,
other conditions are also invalid. This helps reduce the number of test cases.
Example
Input conditions are valid between 1 to 10 and 20 to 30
Hence there are five equivalence classes
• Negative values to 0 (invalid)
• 1 to 10 (valid)
• 11 to 19 (invalid)
• 20 to 30 (valid)
• 31 to Other positive values (invalid)
You select values from each class, i.e., -2, 3, 15, 25, 45
Boundary Value Analysis
• The goal is to select test cases to execute boundary values. It includes maximum, minimum,
inside or outside boundaries, typical values and error values.
• If the input is within the boundary value, it is considered ‘Positive testing.’ If the input is
outside of the boundary value, it is considered ‘Negative testing.’
• The behavior of Negative testing is more likely to be incorrect than the behavior of Positive
testing; and boundaries are an area in which testing is more likely to yield defects.
• If an input condition is restricted between values x and y, then the test cases should be
designed with values x and y as well as values which are above and below x and y.
Example:
Input condition is valid between 1 to 10
Boundary values 0,1,2 and 9,10,11
Decision Table Testing
• A Decision Table is a tabular representation of conditions versus test actions. Conditions are
considered as inputs, while actions are considered as outputs.
• The first task is to identify functionalities where the output depends on a combination of inputs. If
there are large input set of combinations, then divide it into smaller subsets which are helpful for
managing a decision table.
• For every function, you need to create a table and list down all types of combinations of inputs and
its respective outputs. This helps to identify a condition that is overlooked by the tester.
State Transition
• In State Transition technique changes in input conditions change the state of the
Application Under Test (AUT). This testing technique allows the tester to test the behavior of
an AUT.
• The tester can perform this action by entering various input conditions in a sequence.
• In State transition technique, the testing team provides positive as well as negative input test
values for evaluating the system behavior.
Guideline for State Transition:
• State transition should be used when a testing team is testing the application for a limited
set of input values.
• The technique should be used when the testing team wants to test sequence of events
which happen in the application under test.
State Transition:
Experience - based technique:
Exploratory Testing:
Usually, this process is carried out by domain experts. They perform testing just by exploring the functionalities of
the application without having the knowledge of the requirements. Testers can explore and learn the system
while using these techniques. High severity bugs are found very quickly in this type of testing.
Error Guessing:
Error guessing is one of the testing techniques used to find bugs in a software application based on the tester’s
prior experience. In Error guessing, no specific rules are applied.