{"initial":{"previous":["a","b"],"current":["b","c"]},"counterexample":{"previous":"a","current":[]},"tests":[{"name":"addition and removal","input":{"previous":["a","b"],"current":["b","c"]},"expected":{"pass":true,"summary":"Added: c. Removed: a.","checks":[{"name":"added set","pass":true},{"name":"removed set","pass":true}]}},{"name":"invalid shape","input":{"previous":"a","current":[]},"expected":{"pass":false,"summary":"Input needs previous and current arrays of strings.","checks":[{"name":"input shape","pass":false}]}},{"name":"no change boundary","input":{"previous":["a"],"current":["a"]},"expected":{"pass":true,"summary":"Added: none. Removed: none.","checks":[{"name":"added set","pass":true},{"name":"removed set","pass":true}]}}]}