In Boundary Value Analysis Testing Method, if we want to design a test case that computes the square root of an integer value from 1 to 4000, so what values should be included in the test case?

Question

Prepp Team · Accepted Answer

Understanding Boundary Value Analysis (BVA) in Software Testing

Boundary Value Analysis, often shortened to BVA, is a software testing technique used to find errors at the boundaries or limits of input values. It is based on the principle that errors are more likely to occur at the extreme ends of the input domain rather than in the middle.

When applying Boundary Value Analysis, testers create test cases that include values at the boundaries of the input range, as well as values just inside and, sometimes, just outside these boundaries. This helps in identifying defects related to boundary conditions, such as off-by-one errors or issues with comparison operators (>, <, >=, <=).

Designing BVA Test Cases for the Range [1, 4000]

The question asks for test case values using Boundary Value Analysis for an integer range from 1 to 4000, inclusive. This means the valid input range is \([1, 4000]\).

According to standard Boundary Value Analysis principles for a valid range \([Min, Max]\), the typical values selected for testing are:

The minimum boundary value: \(Min\)
A value just above the minimum boundary: \(Min + 1\)
The maximum boundary value: \(Max\)
A value just below the maximum boundary: \(Max - 1\)

Sometimes, values just outside the boundaries (\(Min - 1\) and \(Max + 1\)) are also included, especially if invalid inputs need to be tested, but the options provided focus on values within or adjacent to the valid range.

Applying BVA to the Range [1, 4000]

Given the valid input range is [1, 4000]:

Minimum boundary value (\(Min\)): 1
Value just above the minimum boundary (\(Min + 1\)): \(1 + 1 = 2\)
Maximum boundary value (\(Max\)): 4000
Value just below the maximum boundary (\(Max - 1\)): \(4000 - 1 = 3999\)

So, the core Boundary Value Analysis test cases for the valid range [1, 4000] would typically include the set {1, 2, 3999, 4000}.

Analyzing the Given Options

Let's look at the provided options and see which one matches the set of BVA values derived for the range [1, 4000]:

Option	Test Case Values	Analysis
1	[1, 2, 4000, 4001]	Includes 1 (Min), 2 (Min+1), 4000 (Max), but also 4001 (outside Max boundary).
2	[0, 1, 3999, 4000]	Includes 1 (Min), 3999 (Max-1), 4000 (Max), but also 0 (outside Min boundary).
3	[1, 2, 3999, 4000]	Includes 1 (Min), 2 (Min+1), 3999 (Max-1), 4000 (Max). These are standard BVA values for the valid range.
4	[0, 1, 4000, 4001]	Includes 1 (Min), 4000 (Max), but also 0 (outside Min boundary) and 4001 (outside Max boundary).

Comparing our derived set {1, 2, 3999, 4000} with the options, Option 3 contains exactly these values. These values represent the lower boundary (1), a value just inside the lower boundary (2), a value just inside the upper boundary (3999), and the upper boundary (4000). This set is a classic application of Boundary Value Analysis for a closed interval.

Revision Table: Key BVA Points for Range [Min, Max]

Concept	Description	Value for Range [1, 4000]
Minimum Boundary	The lowest valid input value.	1
Value above Minimum	The value immediately greater than the minimum within the valid range.	2
Maximum Boundary	The highest valid input value.	4000
Value below Maximum	The value immediately less than the maximum within the valid range.	3999

Additional Information on Boundary Value Analysis Testing

Boundary Value Analysis is a type of black-box testing. It works well with Equivalence Partitioning. First, testers divide the input domain into partitions (groups of values expected to behave similarly). Then, BVA is applied to the boundaries of these partitions.

For example, if the range for calculating the square root was different for different sub-ranges (e.g., 1-100, 101-1000, 1001-4000), each sub-range would be an equivalence partition, and BVA would be applied to the boundaries of each partition.

Testing boundary values is crucial because programmers often make mistakes in handling these edge cases, for instance, using < instead of <= or vice versa, leading to unexpected behavior at the boundaries.