Assert that the rich text field with a label contains, or does not contain, a text.
Examples
Then the rich text field "Body" should contain "The full story."
Then the rich text field "Body" should not contain "An old sentence"
Then the rich text field "Body" should contain "Launch day"
And the rich text field "Introduction" should contain "Welcome."
And the rich text field "Body" should not contain "Lorem ipsum"
Pattern
Then(/^the rich text field "([^"]*)" should( not)* contain "([^"]*)"$/, …)
Part of @webship-js/craft-cms-steps (github.com/webship/craft-cms-steps), a step pack for Webship-js 2.0.x.