Boundary Value Analysis

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Boundary value analysis is a test technique to test software by testing the values at both sides of and on the boundaries of the valid input data groups (partitions). You get the data group using Equivalence Partitioning. You test how the software works with the boundary values. Boundary value analysis is based on software requirements and technical specifications.

Boundary Value Analysis Examples

• You test a field that accepts age between 21 and 80 (valid partition). You test the values: 20 (unacceptable), 21 (acceptable), 22 (acceptable), 79 (acceptable), 80 (acceptable), and 81 (unacceptable).
• You test a function that accepts an integer percentage between 0 and 100. You test the values: -1, 0, 1, 99, 100, 101, and test if each test input is accepted or rejected appropriately.
  
• You test your website that accepts a username between 10 and 15 characters long. You set up usernames with character lengths of 9 (unacceptable), 10 (acceptable), 11 (acceptable), 14 (acceptable), 15 (acceptable), and 16 (unacceptable) characters.

Tips for Boundary Value Analysis

• First, use equivalence Partitioning to identify the input data groups .
• Test both valid and invalid boundary values to test if the software handles them correctly.
• Test the relevant functionality of the software that depends on each test input.
• Use tools to automate testing tasks, such as generating test inputs, executing tests, and reporting results.

FAQ (interview questions and answers)

1. What is the purpose of boundary value analysis?
   The purpose of boundary value analysis is to find defects that occur at the edges of the input test data groups.
2. What is the advantage of boundary value analysis?
   It reduces effort by testing only the test inputs at the boundaries, instead of testing all possible values. It can find errors that are not visible in equivalence partitioning, because it tests the inputs at or near the boundaries and not just one input in the entire partition.
3. What is the disadvantage of boundary value analysis?
   Similar to equivalence partitioning, it assumes that your software treats each input within a group (partition ) identically. As a result, it can miss a defect that occurs only with specific values within a group. It can be difficult to identify the boundary values for complex software.
4. Is boundary value analysis a type of black-box testing?
   Yes, it is a technique that tests the software ignoring knowledge about its structure or code.

Remember to just comment if you have any doubts or queries.