Test Design Techniques

Test Design Techniques Important Terms: The test development process Test case specification, test design, test execution schedule, test procedure specification, test script, traceability. Categories of test design techniques Black-box test design technique, specification-based test design technique, white-box test design technique, structure-based test design technique, experience-based test design technique. Specification-based or black box techniques Boundary value analysis, decision table testing, equivalence partitioning, state transition testing, use case testing. Structure-based or white box techniques Code coverage, decision coverage, statement coverage, structure-based testing. Experience-based techniques Exploratory testing, fault attack. Choosing test techniques No specific terms. Test Design Techniques Specification-based/Black-box techniques Structure-based/White-box techniques Experience-based techniques I) Specification-based/Black-box techniques Equivalence partitioning Boundary value analysis Decision table testing State transition testing Use case testing Equivalence partitioning Inputs to the software or system are divided in to groups that are expected to exhibit similar behavior Equivalence partitions or classes can be found for both valid data and invalid data Partitions can also be identified for outputs, internal values, time related values and for interface values. Equivalence partitioning is applicable all levels of testing Boundary value analysis Behavior at the edge of each equivalence partition is more likely to be incorrect. The maximum and minimum values of a partition are its boundary values. A boundary value for a valid partition is a valid boundary value; the boundary of an invalid partition is an invalid boundary value. Boundary value analysis can be applied at all test levels It is relatively easy to apply and its defect-finding capability is high This technique is often considered as an extension of equivalence partitioning. Decision table testing In Decision table testing test cases are designed to execute the combination of inputs Decision tables are good way to capture system requirements that contain logical conditions. The decision table contains triggering conditions, often combinations of true and false for all input conditions It maybe applied to all situations when the action of the software depends on several logical decisions State transition testing In state transition testing test cases are designed to execute valid and invalid state transitions A system may exhibit a deferent response on current conditions or previous history. In this case, that aspect of the system can be shown as a state transition diagram. State transition testing is much used in embedded software and technical automation. Use case testing In use case testing test cases are designed to execute user scenarios A use case describes interactions between actors, including users and the system Each use case has preconditions, which need to be met for a use case to work successfully. A use case usually has a mainstream scenario and some times alternative branches. Use cases, often referred to as scenarios, are very useful for designing acceptance tests with customer/user participation II) Structure-based/White-box techniques Statement testing and coverage Decision testing and coverage Other structure-based techniques condition coverage multi condition coverage Statement testing and coverage: Statement An entity in a programming language, which is typically the smallest indivisible unit of execution Statement coverage The percentage of executable statements that have been exercised by a test suite Statement testing A white box test design technique in which test cases are designed to execute statements Decision testing and coverage Decision A program point at which the control flow has two or more alternative routes A node with two or more links to separate branches Decision Coverage The percentage of decision outcomes that have been exercised by a test suite 100% decision coverage implies both 100% branches coverage and 100% statement coverage Decision testing A white box test design technique in which test cases are designed to execute decision outcomes. Other structure-based techniques Condition A logical expression that can be evaluated as true or false Condition coverage The percentage of condition outcomes that have been exercised by a test suite Condition testing A white box test design technique in which test cases are designed to execute condition outcomes Multiple condition testing A white box test design technique in which test cases are designed to execute combinations of single condition outcomes III) Experience-based techniques Error guessing Exploratory testing Error guessing Error guessing is a commonly used experience-based technique Generally testers anticipate defects based on experience, these defects list can be built based on experience, available defect data, and from common knowledge about why software fails. Exploratory testing Exploratory testing is concurrent test design, test execution, test logging and learning , based on test charter containing test objectives and carried out within time boxes It is approach that is most useful where there are few or inadequate specifications and serve time pressure. For Software Testing Information visit: www.gcreddy.net 2 For QTP Information visit: www.gcreddy.com