test: assert validateOutput verifies schema for expected media type

[mtjandra]

Addresses: #2713

Summary

Unresolved fix with test to communicate bug.

Checklist

• The basics
  • I tested these changes manually in my local or dev environment
• Tests
  • Added or updated
  • N/A
• Event Tracking
  • I added event tracking and followed the event tracking guidelines
  • N/A
• Error Reporting
  • I reported errors and followed the error reporting guidelines
  • N/A

Additional context

Please feel free to fix this bug, unsure if I will get to fixing this.