How to write a test case from use case

Use Case to Test Case Conversion:
Let us see the process for generating test cases from a fully detailed use case. The first step is to for each use case, generate a full set of high level test scenarios. For each high level scenario, identify at least one positive or negative test case and the conditions that will make it "execute". Then for each test case, identify the data values with which to test. At last document the test case as a combination of stepps and expected results including the above identified data values.

Tester should consider following concepts under preparation of test case:

• Ensure each section in use case has one or many test cases.
• Ensure integrity between modules are maintained throughout the test cases.
• Need to ensure inter dependencies external to the system are taken care in test cases.