Test case design is a critical phase in the software development lifecycle, involving the creation of detailed test cases to systematically evaluate the functionality and performance of an application. It's akin to crafting a blueprint for a building, ensuring every aspect is meticulously examined to identify and rectify potential flaws.

Key Components of a Test Case:

Test Case ID: A unique identifier for easy reference.

Test Description: A concise summary of the test's purpose.

Pre-conditions: Specific conditions that must be met before executing the test.

Test Steps: A sequence of actions to be performed.

Test Data: Input values used to test the system.

Expected Results: The anticipated outcomes of the test steps.

Actual Results: The observed results after executing the test steps.

Pass/Fail: A clear indication of whether the test was successful or not.

Post-conditions: Any actions or states to be restored after the test.