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
Advantages 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 Partitioning (ECP)
- It is a specification-based or black-box technique
- The input data is divided into different equivalence data classes – which are generally termed as ‘Valid’ and ‘Invalid’.
- 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 ’cause-effect’ 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.