Boundary Value Analysis is a black-box testing technique where test cases are designed to include values at the edges of input ranges.
Why?
Most defects tend to occur at the boundaries of input domains rather than in the center. BVA helps catch off-by-one errors or logic issues near limits.
Basic Principle:
If an input field accepts a value from X to Y, then test the values:
-
Just below the minimum:
X - 1
-
At the minimum:
X
-
Just above the minimum:
X + 1 -
Just below the maximum:
Y - 1 -
At the maximum:
Y -
Just above the maximum:
Y + 1
Example Scenario
Requirement:
A user must enter an age between 18 and 60 (inclusive).
Input Range: 18 – 60
| Test Case ID | Input Value | Expected Result | Reason |
|---|---|---|---|
| TC001 | 17 | Invalid | Just below min value |
| TC002 | 18 | Valid | Lower boundary value |
| TC003 | 19 | Valid | Just above lower boundary |
| TC004 | 59 | Valid | Just below upper boundary |
| TC005 | 60 | Valid | Upper boundary value |
| TC006 | 61 | Invalid | Just above max value |
Where is BVA used?
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Form validation (age, amount, date, quantity)
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Range validation
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Input fields with numeric limits
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Sliders, pagination, or scrollbars
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API validations (min/max length, numeric boundaries)
Summary:
| Feature | Value |
|---|---|
| Type | Black-box Testing Technique |
| Focus | Input boundaries |
| Goal | Catch edge case bugs |
| Test Count | Usually 6 test cases per input field |