Improve test failure output for better debugging

[Lochit-Vinay]

SOLVES ISSUE #25
While going through the testing-center repository, I noticed that when a test fails, the output is a bit hard to read and doesn’t give enough context at a glance.
This change just improves the failure message so it’s easier to understand what went wrong.
Earlier, the failure output was mostly a single line showing expected and actual values together, which made it harder to quickly spot the issue.
With this change, the output is a bit more structured and includes:

• interface name
• test case name
• input used
• expected vs actual output
  No changes to the test logic itself, just improving how failures are displayed.