Question: How can we write a good test case?
Answer: Essentially a test case is a document that carries a Test Case ID no, title, type of test being conducted, Input, Action or Event to be performed, expected output and whether the Test Case has achieved the desired Output(Yes \ No)
Basically Test cases are based on the Test Plan, which includes each module and what to be tested in each module. Further each action in the module is further divided into testable components from where the Test Cases are derived.
Since the test case handles a single event at a time normally, as long as it reflects its relation to the Test plan, it can be called as a good test case. It does not matter whether the event passes or fails, as long as the component to be tested is addressed and can be related to in the Test Plan, the Test Case can be called a good Test Case.