These are expected in the project to allow scalable and reliable development.
Business team needs to provide
User Stories
Clear and concise user stories which is along the lines of
As a persona (type of user), I wish to do this functionality, in order to obtain this result
with these kind of details
Process flow
Validation rules
Acceptance Criteria which are clear and concise. There should be enough detail to have confidence that the story has been written and understood successfully. Generally,
If this condition occurs / this action is taken, these are the expected results
Here’s a good explanation: Acceptance Criteria - What Is It? Examples and Templates Included (zepel.io)
Development team needs to provide
Test Driven Development
Test driven development
to ensure that every time changes are made the system reports any errors on tests
Good definition here: What is Test Driven Development (TDD)? | Agile Alliance
Automated Testing
Integrated regression testing to check the overall system is not affected by changes to the system
User interface testing as automated as possible in order to show resulting errors
Selenium, or something like it: