"Experts in Wireless"

Hierarchy of Test

Module Testing

Modular testing is intended to verify and validate the fundamental building blocks with a system. It involved checking that each feature has been implemented and is working as expected. In an electronic system a module may be a full PCB or a simple circuit function within a PCB (for example a PLL, filter or PSU).

Interface Testing

As the modules are constructed and tested they are then linked together to check that they work with each other. Two modules that have passed all their tests, when connected to each other may produce a new component full of faults. Interface Testing is not focused on what the modules are doing but on how they interact.

The "System Design" defines relationships between modules, and this involves stating:

Error Handling
Power Supply
Electrical and Control Interfaces
Timing Requirements

The tests are organised to check all the interfaces, until all the modules have been built and interfaced to each other producing the whole system.

System Testing

Once the entire system has been built it has to be tested against the "System Specification" to check if it delivers the features required. System Testing is not about checking individual parts of the design, but about checking the system as a whole. System testing can involve a number of specialist types of test to see if all the functional and non-functional requirements have been met.

Acceptance Testing

Acceptance testing checks the system against the "Requirements". It is similar to systems testing in that the whole system is checked but the important difference is the change in focus:

Systems Testing checks that the system that was specified has been delivered.
Acceptance Testing checks that the system delivers what was requested.

Acceptance testing is normally performed by a customer to verify that they have received what they asked for.

Release Testing
Even if a system meets all its requirements, it still needs to be verified that it meets the needs of its users. Release testing is widely associated with Alpha & Beta testing or field trials.

Regression Tests
Regression tests are carried out whenever a change is made (either at module or sub-system level). They are a necessity in modern and complex systems where a change can have undesired side effects in other modules or at a system level.