Quality is delighting customers
It varies from Application to Application .. ! If the Project schedule permits ( It further depends on the complexity of the Intended system too ) , one may write separate test cases for each and every object or a single test cases can be written covering all of the fields ..!
It further depends on Field level validation and Form level validation too... !
u hav to write for every field if FRS dicument is available
eg: in a registration form fileds like First name:
click submit buton to register
so u hav to write test case for each filed to verity the functionality of submit button
From my practice, it depends:
1) If my form use these fields separately to generate output, I will write them separately. The reason is that it is easy to understand and review.
2) If my form use these fields together to generate output, I will write them together follows pairwise technique. The reason is that it can cover issue easier.
I think also this is different according to other factors such as. the budget of the project, because writing a test case for each field will consume time which will reflect on the budget (MD). Also according to the criticality of these fields, if these fields have deep impact on the functionality of the system, so there should be special test cases to verify that these fields are working correctly. on other hand if these fields have low impact its not logic to waste time and money in writing test cases for these fields.
That's really depends on the project scope (testing time) and kind of application under test.
So if time permits we should go for each field, I mean we should write test cases for each field. Which specify the behavior of each field. I mean mandatory fields, non mandatory fields or few fields accept specific test input.
So all such things should be covered in your test cases.