`--format` argument fails to change output of command

Start at the implementation or entry point for wp plugin verify-checksums and trace how its --format option is passed to output handling. Reproduce the six commands listed, then verify that each supported format changes the output while checksum verification remains correct.

Summary

While trying to use the --format argument with the wp plugin verify-checksums commands I found the output wouldn't change. I've tried all format options listed and none of them change the format outputted.

Steps to reproduce

1. Run command ‘wp plugin verify-checksums --all’
2. Run command ‘wp plugin verify-checksums --all --format=json’
3. Run command ‘wp plugin verify-checksums --all --format=csv’
4. Run command ‘wp plugin verify-checksums --all --format=count’
5. Run command ‘wp plugin verify-checksums --all --format=yaml’
6. Run command ‘wp plugin verify-checksums --all --format=table’
7. Observe the output of all six commands is identical.

Environment

• WP-CLI 1.5.1

Results and impacts

Severity – Moderate

Expected Results: Output in the format specified in the command line argument

Actual Results: The output does not follow the format specified.

This command has been incredibly useful to me in one off scenarios, but I can't use it effectively in scripts and Unix pipes without the option of a clean output format.