Boundary testing is a software testing technique that focuses on testing the software’s behavior at the boundaries or limits of input values or system parameters. The goal of boundary testing is to identify any errors or unexpected behavior that may occur when the input or system parameter is at its minimum, maximum, or just beyond those boundaries.
The rationale behind boundary testing is that errors often tend to occur at the edges or boundaries of acceptable input values rather than in the middle. By testing these boundary conditions, it helps ensure the software handles them correctly and does not produce incorrect or unexpected results.
Here are a few examples to illustrate boundary testing:
- Input Value Range: If a software component accepts input within a specific range (e.g., a number between 1 and 100), boundary testing would involve testing the behavior of the software when the input is at the minimum value (1), maximum value (100), and values just below or above those boundaries (0, 101). This helps identify any issues related to range checking, overflow, or underflow.
- String Length: If the software has limitations on the length of input strings (e.g., a maximum of 50 characters), boundary testing would involve testing the behavior when the input is at the maximum length (50 characters), an empty string, and strings just below or above the length limit (49 characters, 51 characters). This helps uncover any issues related to buffer overflows, string truncation, or input validation.
- Date and Time Values: If the software deals with dates or time values, boundary testing would involve testing scenarios such as the earliest and latest valid dates, leap years, dates just before and after the month or year boundaries, and edge cases like time zone changes or daylight saving transitions.
- System Resources: In some cases, boundary testing may involve testing the behavior of the software when system resources reach their limits. For example, testing how the software handles when the memory usage is at its maximum, or when the number of concurrent connections or file handles exceeds the allowed limit.
Boundary testing helps ensure that the software can handle critical edge cases and boundary conditions without causing errors, crashes, or producing incorrect results. By testing the boundaries and just beyond them, it helps uncover potential issues and allows developers to make necessary adjustments to improve the software’s robustness and reliability.