test_client: Refactor and simplify tests for a better readability
This:
- Aligns all tests to use
json
format output so the assertion check is simpler (no tampering with caplog record) - Simplify the caplog record assertion check in failure scenarios
- Drop dead code
- Rename tests with a
test_cli_
prefix so it's simpler to run them separately from the rest
Test Plan
tox
Migrated from D4214 (view on Phabricator)