Methods of Black box Testing

Methods of Black box Testing

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.. Continuing the Beginners Guide to Software Testing series

The following basic techniques are employed during black box testing:

  • Equivalence Class
  • Boundary Value Analysis
  • Error Guessing

Equivalence Class:

  • For each piece of the specification, generate one or more equivalence Class
  • Label the classes as “Valid” or “Invalid”
  • Generate one test case for each Invalid Equivalence class
  • Generate a test case that covers as many Valid Equivalence Classes as possible

Equivalence Class

An input condition for Equivalence Class:

  • A specific numeric value
  • A range of values
  • A set of related values
  • A Boolean condition


 Equivalence classes can be defined using the following guidelines:

  • If an input condition specifies a range, one valid and two invalid equivalence class are defined.
  • If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.
  • If an input condition specifies a member of a set, one valid and one invalid equivalence classes are defined.
  • If an input condition is Boolean, one valid and one invalid classes are defined.

Boundary Value Analysis

  • Generate test cases for the boundary values.
  • Minimum Value, Minimum Value + 1, Minimum Value -1
  • Maximum Value, Maximum Value + 1, Maximum Value – 1

Error Guessing.

  • Generating test cases against to the specification.

Go back to Test Design Techniques

Black Box Testing

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.. Continuing the Beginners Guide to Software Testing series

What is Black Box Testing?

  • Test the correctness of the functionality with the help of Inputs and Outputs.
  • User doesn’t require the knowledge of software code.
  • Black box testing is also called as Functionality Testing.
  • Testers make sure that software is working as per the requirements.

It attempts to find errors in the following categories:

  • Incorrect or missing functions.
  • Interface errors.
  • Errors in data structures or external data base access.
  • Behavior or performance based errors.
  • Initialization or termination errors.

Read – Approaches used in Black Box Testing

Fault, Error and Failure

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.. Continuing the Beginners Guide to Software Testing series

Fault : It is a condition that causes the software to fail to perform its required function.
Error : Refers to difference between Actual Output and Expected output.
Failure : It is the inability of a system or component to perform required function according to its specification.
IEEE Definitions

  • Failure: External behavior is incorrect
  • Fault: Discrepancy in code that causes a failure.
  • Error: Human mistake that caused fault

Note:

  • Error is terminology of Developer.
  • Bug is terminology of Tester

What Is Software Testing?

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.. Continuing the Beginners Guide to Software Testing series

Definitions of Software Testing –

  • It is the process of Creating, Implementing and Evaluating tests.
  • Testing measures software quality
  • Testing can find faults. When they are removed, software quality is improved.
  • Testing is executing a program with an indent of finding Error/Fault and Failure.
  • IEEE Terminology : An examination of the behavior of the program by executing on sample data sets.