Complete testing in software development includes ut, IT, St, UAT

The test environment completed in software development includes ut, IT, St, and UAT.

 Ut = unit test it = System Integration Test
St = System Test UAT = User Acceptance Test (commonly known as acceptance test) 

 Ut (unit test ): 
Unit test tasks include:
1. Test the Module Interface;
2. Test the local data structure of the module;
3. Test the module boundary condition;
4. All independent path tests in the module;
5. test each error handling path of the module .;

It (integration test ): 
System integration test (also known as system integration test) or integrated testing, the integration test phase focuses on the black box method. In the early stages of bottom-up integration, white box testing accounts for a certain proportion, with the continuous development of integration testing, this proportion will become fewer and fewer during the testing process. Gradually, black box testing occupies a dominant position.

 ST (System Test ): 
From a technical point of view, system testing is the last step in the entire test phase. All development and testing work together to form a software system with certain functions.
This phase mainly tests the accuracy and integrity of the system.
Mainly:
Function validation testing, running testing, intensity testing, recovery testing, and security testing.
System Testing testers are jointly tested by test members (or quality assurance personnel) or test members with users. After the entire system is developed, it will be performed before being delivered to users. At this stage, the entire system is completely tested using the black box method.

 UAT (Acceptance Test, User Acceptance Test ): 
The acceptance test indicates to future users that the system can work as required.
After integration testing, all modules have been assembled into a complete software system according to the design, and interface errors have been basically ruled out. Then, the effectiveness of the software should be further verified, this is the task of acceptance testing, that is, the functions and performance of the software are as reasonably expected by the user.

 A project starts from the design, and a project's success starts from the test. A good test system can solve most of the critical bugs in the system before the system goes online. The perfection and maturity of the test system is also an important indicator to measure the overall level of a software enterprise. Testing is often ignored because it can be recessive and does not produce direct benefits for software development enterprises, but it is the final guarantee of software quality, and even an important factor for project success!