Chapter 4 – Test Analysis and Design
Equivalence Partitioning – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A black-box test technique in which test cases are designed to exercise partitions of equivalent inputs or outputs, on the assumption that all members of a partition are processed in the same way.
In simple words
Group inputs that the system should treat identically, then pick one value from each group. That way you cover behaviour without testing every possible value.
Exam tip
Always create at least one valid and one invalid partition per input, and pair EP with Boundary Value Analysis for full coverage.
Related terms
- Boundary Value AnalysisBugs cluster at the edges of allowed ranges. So if a field accepts 1–100, you test 0, 1, 100, and 101 instead of only picking a value from the middle.
- Decision Table TestingWhen behaviour depends on combinations of conditions (like discount rules), you list every condition and expected action in a table and turn each column into a test case.
- Black-Box TestingYou design tests only from the spec or behaviour — inputs and expected outputs — without looking at the code.
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