System integration :Testing of system as one.

System Integration Testing is a process of verifying that the system meets its requirements, and validating that the system performs in accordance with the customer or user expectations.

                 System integration testing involves the overall testing of a complete system of many subsystem components or elements. The system under test may be composed of hardware, or software, or hardware with embedded software, or hardware/software with human-in-the-loop testing. The system integration process starts with assembling the constituent parts of a system in a logical, cost-effective way with an exhaustive checking of system execution including a full -functional check out

                                       

System  integration Testing is a type of black box testing technique thus the knowledge of internal code in not required. It is a high level testing always performed after integration testing. The user can perform different type of tests under System Testing which can be broadly classified as

1. Functional Testing

2. Non Functional Testing

Following points are checked and kept under consideration while doing system integration testing

Check whether the system is made according to the customer needs as per the requirements . It’s checked whether system meets both the functional and non-functional requirements of the system

In the system integration all the components/modules of the system are combined as a whole , due to this integration many errors may arise which can differ from the expectation and may not provide the expected results .hence the testing is done to find the defects or bugs in all the interfaces as well as whole system

To check if the system behaves as per the expectations, the product is checked in the production like environment so that the product behavior could be checked in the real life environment.  

Difference between System Integration testing and Integration testing  

                                

             System  integration Testing                       Integration testing

Test cases are based on real life scenarios.	Test cases are developed to check the interaction between the modules.
Completed product is tested in order to check if it meets requirements	Modules / components are checked  to   see if they give the expected results
It is black box testing technique	It is a combination of both black box and white box testing technique
Testing is done as whole including all the external interfaces wherein any defects found is regarded as the defect in the whole system	The testing is performed on interface between individual module so any defect found is module specific
High level testing is done in this , where in testing types like sanity, usability, maintenance regression are done	Integration testing include low level testing with techniques approaches like top down , bottom up sandwich and big bang.