Basic concepts of unit testing, integration testing, and System Testing

UnitTestIs to test each program Unit implemented by source code, and check whether each program module correctly implements the specified function. Integration Testing assembles tested modules to test the structure of the software architecture related to the design. System tests include validated software in the actual operating environment and are combined with other system components for testing.
Unit Test(Unit Testing)

The unit test, also known as the module test, is a test of the correctness of the program module, the smallest unit of software design. The purpose is to discover various internal errors of each module. Unit tests need to design test cases from the internal structure of the program. Multiple modules can perform unit tests in parallel.
Integration Test (Integrated Testing)
Usually, in unit testingBasicAll modules need to be assembled into a system according to the design requirements. The following issues need to be considered:
-Whether data transmitted through the Module Interface is lost when each module is connected;
-Whether the functions of one module will adversely affect the functions of the other module;
-The combination of sub-functions can meet the expected requirements of the parent function;
-Check whether the global data structure is faulty;
-Whether the error of a single module is accumulated and amplified to an unacceptable degree.
Integration tests can be conducted at the same time as unit tests to discover and eliminate possible problems in module connections, and ultimately constitute the required software system. Subsystem integration testing, especially component testing, is used to identify the inconsistency between the integrated subsystem and the System Requirement Specification.

System Test (System Testing)

System testing is a software that will pass validation testing as an element of the entire computer-based system, combined with computer hardware, peripherals, some supporting software, data and personnel and other system elements, a series of Assembly tests and validation tests on computer systems in the actual operating environment. The purpose of a system test is to compare it with the requirement definition of the system to find out the inconsistency or conflict between the software and the definition of the system.