Approach to write tests in laravel?

I have read the documentation of laravel it only explained the techniques. I am new in testing I am unable to understand in which case I should write the test. For Example, My form has almost 50 fields. I am checking validations in the controller. Now those validations are working on different use cases because I am also using if-else invalidation. basically, I am totally new to the testing. I am wondering what should be the proper approach for testing. There multiple conditions in the controller how should I check all those conditions.

Do I need to pass data for each if and else. these are multiple validations in controllers. Do i need to send data for all validations ? Or is there any kind of generic approach?

via Chebli Mohamed