{"abstract":"The operation returns a result or retained state that violates this contract: Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels.","category":"Iterator consumption","checks":4,"contract":"Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","contract_signature":"x, y=None","evaluation_group":"model-9710e09d23275a0e","failed_approach":"takewhile implements prefix retention rather than initial-run removal.","family":"xr-dropwhile-stops-testing-after-first-failure","id":"FA-4546","implementations":{"attempt":{"sha256":"627976f8ddefa2f8cf1fc4fa600734c5e00f7785747cfd7f9d89ad92d079b647","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport itertools as it\nfrom collections import deque\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return list(it.takewhile(lambda v:v!=y,iter(x)))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('later sentinel retained', solve(['s', 'a', 's', 'b'], 's'), ['a', 's', 'b'])\ncheck('all dropped', solve(['s', 's'], 's'), [])\ncheck('no initial sentinel', solve(['a', 's'], 's'), ['a', 's'])\ncheck('empty', solve([], 's'), [])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"3469cbe416e5ccb94e6e59cc93a3bbee4a522728730ff3e30a9a9b81f8de515f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport itertools as it\nfrom collections import deque\nN = 1\nobservations = []\ndef solve(x, y=None):\n    return [v for v in x if v!=y]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('later sentinel retained', solve(['s', 'a', 's', 'b'], 's'), ['a', 's', 'b'])\ncheck('all dropped', solve(['s', 's'], 's'), [])\ncheck('no initial sentinel', solve(['a', 's'], 's'), ['a', 's'])\ncheck('empty', solve([], 's'), [])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":" This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"xr-dropwhile-stops-testing-after-first-failure","generated_at":"2026-09-29T14:37:40.317540+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.","root_cause":"Global filtering removes matching values after the initial dropped run.","sha256":"52a19c410d6759e24b18d5ad11c12c9ffe3429ce883496b25d193cd149de6da1","title":"Dropwhile stops testing after first failure · case 01","variant":1,"variant_policy":"Five execution reruns of a fixed adversarial fixture suite; variant number does not alter semantic inputs.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":37.137,"exit_code":1,"observations":[{"actual":[],"check":"later sentinel retained","expected":["a","s","b"],"passed":false},{"actual":[],"check":"all dropped","expected":[],"passed":true},{"actual":["a"],"check":"no initial sentinel","expected":["a","s"],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"later sentinel retained\", \"actual\": [], \"expected\": [\"a\", \"s\", \"b\"], \"passed\": false}, {\"check\": \"all dropped\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"no initial sentinel\", \"actual\": [\"a\"], \"expected\": [\"a\", \"s\"], \"passed\": false}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.549,"exit_code":1,"observations":[{"actual":["a","b"],"check":"later sentinel retained","expected":["a","s","b"],"passed":false},{"actual":[],"check":"all dropped","expected":[],"passed":true},{"actual":["a"],"check":"no initial sentinel","expected":["a","s"],"passed":false},{"actual":[],"check":"empty","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"later sentinel retained\", \"actual\": [\"a\", \"b\"], \"expected\": [\"a\", \"s\", \"b\"], \"passed\": false}, {\"check\": \"all dropped\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"no initial sentinel\", \"actual\": [\"a\"], \"expected\": [\"a\", \"s\"], \"passed\": false}, {\"check\": \"empty\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}