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• # What is Black Box Testing? | Techniques

• Black Box Testing is testing technique having no knowledge of the internal functionality/structure of the system
• It is also called Behavioural, Functional, Opaque-Box, Closed-Box etc
• focuses on testing the function of the program or application against its specifications
• Determines whether combinations of inputs and operations produce expected results

## Black box Testing Techniques

• Equivalence partitioning.
• Boundary Value Analysis
• Decision table testing
• State Transition Testing
• Error Guessing

## AdvantagesÂ of Black-Box Testing

• More effective on larger units of code than glass box testing
• Tester needs no knowledge of implementation, including specific programming languages
• Tester and programmer are independent of each other

Below is the overview of each black black box technique.

### 1) Equivalence partitioning

• It is also known as Equivalence Class PartitioningÂ (ECP)
• It is a specification-based or black-box technique
• The input data is divided into different equivalence data classes â€“ which are generally termed as â€˜Validâ€™ and â€˜Invalidâ€™.
• Test only one condition from each partition or equivalence.
• It reduces the number of test cases to a finite list of testable test cases covering maximum possibilities

### 2) Boundary Value analysis

• Boundary value analysis is a selection of test cases that takes boundary values as inputs. It is based on the assumption that errors are usually found on boundaries.
• It can be applied at all levels/phases of testing
• Boundaries are good place to look for defects
• Boundary Value Analysis is the next part of Equivalence Partitioning for designing test cases where test cases are selected at the edges of the equivalence classes.

### 3) Decision table testing

• A black-box test design technique in which test cases are designed to execute the combinations of inputs and their corresponding behaviour shown in a decision table.
• It is referred to as a â€™cause-effectâ€™ table
• Each column can then be considered as a test case of a business rule
• Decision Table Testing is good for testing business rules or combinations
• Contains conditions (Input) and actions (Outputs)

### 4) State Transition Testing

• A black box testing technique
• State-transition diagrams are very useful for describing the behaviour of a system and are part of the Software Design Document.
• Tests are designed to execute valid and invalid state transitions
• State-Transition diagrams are an excellent tool to capture certain types of system requirements and to document internal system design.
• This technique is used when features of a system are represented as states, which transform to another state.