How to write software function testing

The functional testing of the testing object should focus on all the testing requirements that can be directly tracked to use cases or business functions and business rules. The purpose of these tests is to check whether data is correctly accepted, processed, and retrieved, and whether business rules are correctly implemented. This type of testing is based on the black box method, that is, through the graphical user interface (GUI) to interact with the application and analyze the output results to verify the application and its internal processes.

Purpose:Ensure that the test object functions properly, including navigation, data input, processing, and retrieval.
Test method:

Use valid and invalid data to execute various use cases, use case streams, or functions to verify the following:

1. Expected results are obtained when valid data is used.

2. An error message or warning message is displayed when invalid data is used.

3. All business rules have been correctly applied.

Completion criteria:

1. All planned tests have been executed.

2. All discovered defects have been solved.

Special considerations: determine or describe those that will affect the implementation and execution of functional tests (internal or external)