Then the Joomla version should start with "6"

Assert the Joomla version the System Information page reports. "be" compares the whole version ("6.2.0"), "start with" a part of it ("6" or "6.2").

Examples

Then the Joomla version should start with "6"
Then the Joomla version should be "6.2.0"
Then the Joomla version should start with "6.2"
And the Joomla version should not start with "3"
Then the Joomla version should not be "4.0.0"

Pattern

Then(/^the Joomla version should( not)* (be|start with) "([^"]*)?"$/, …)

Part of @webship-js/joomla-steps (github.com/webship/joomla-steps), a step pack for Webship-js 2.0.x.