Software Testing - The Differences between Load Testing and Stress Testing

Load Testing

A load test is usually conducted to understand thebehaviorof the system under a specificexpected load. This load can be theexpected concurrent number of users on the application performing a specific number of transactions within the set duration. Load test aimed to determine the performance of a test subject under a predefined test load. After a load test, unless the test subject fails during the testing procedure, the test subject can be put in to its normal use.

Stress Testing

Stress test understand the upper limits of capacity within the system. This kind of test is done to determine the system's robustness in terms ofextreme load and helps application administrators to determine if the system will perform sufficiently if the current load goeswell above the expected maximum.Stress test is carried out to determine the maximum stress levels that can be achieved by an experimental subject before it breaks. In other words, the experimental subject is subjected to exceptionally high stress levels than they are expected to carry in normal usage. After a stress test is performed the undergone experimental subject is destructed, or rendered useless. Since the test will break the test subject, it is not performed on the actual object, but the test is performed on a sample obtained or on a truth full model of the original subject.It is very important, that the samples or the models have to be representative of the actual test subject.

The Differences between Load and Stress Testing

• Load test is carried out to determine the performance of a test subject under loads that occur at the normal working condition.

• Stress test is carried out to determine the maximum stress/load carrying capacity of a test subject before it breaks.

• Load test is non destructive test.

• Stress test is a destructive test.

• Load test is performed on the actual test subject or on a part of it.

• Stress test is performed on a representative sample obtained from the test subject.

So the bottom line is: if you are testing normal, expected load (you know the system will be used by up to 100 users at a time), this isload testing. But when you want to determine how the system behaves under extreme load (DoS) and when it breaks, this isstress testing.