This was meant as a smoke test...

A smoke test that only works on your machine :-)

What‘s a good alternative?

How about:

$ wp cli version
WP-CLI 2.8.1
$wp eval 'echo \WP_CLI\Utils\http_request( "GET", "https://api.wordpress.org/core/version-check/1.6/" )->body;' --skip-wordpress
<PHP serialized string with version numbers>

That would at the very least test whether the update worked and whether regular execution and the integration with Requests works.
Note: The above example that Daniel provided mostly just tested the SSH subsystem. The entire option retrieval logic is executed on whatever version is installed on his server.

Added in c532c80

How about:

$ wp cli version
WP-CLI 2.8.1
$wp eval 'echo \WP_CLI\Utils\http_request( "GET", "https://api.wordpress.org/core/version-check/1.6/" )->body;' --skip-wordpress
<PHP serialized string with version numbers>

That would at the very least test whether the update worked and whether regular execution and the integration with Requests works.
Note: The above example that Daniel provided mostly just tested the SSH subsystem. The entire option retrieval logic is executed on whatever version is installed on his server.