Performance Testing - Software Testing: Testing Across the Entire Software Development Life Cycle - page 129

Chapter 9

Performance Testing

LEARNING OBJECTIVES

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to define the kind of testing that measures the speed of software
to analyze techniques that simplify the intrinsically complex performance testing of
software transaction mixes
to assess the potential business liabilities of ignoring performance testing

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9.1 INTRODUCTION

We advance from testing techniques that validate the software behavior to testing
techniques that validate the software “speed.” Speed in this context means that a
tester measures aspects of software response time while the software is laboring un-
der a controlled amount of work, called a “workload.” To make the software reveal
its true production speed, the tester must execute the performance tests in a testing
environment that approximates the intended production environment as closely as
possible. These execution testing techniques are fundamentally different in objective
and approach from functional testing where the objective is validating correct code
behavior regardless of speed.
Performance testing occurs after the functional testing is mostly completed and
the software has become quite stable (fewer and fewer changes or corrections). Func-
tional defects in the software may be revealed during performance testing, but this
is not the testing objective.
The objective of performance testing is to validate the software “speed” against
the business need for “speed” as documented in the software requirements. Software
“speed” is generally defi ned as some combination of response time and workload
during peak load times. These peak load times may occur during lunch time, at the
opening of the stock market day, or after midnight when all online customers are in
bed (overnight batch workload). Performance testing is achieved by a series of tests