{ "schemaVersion": 1, "tool": { "name": "skewcheck", "version": "0.1.0" }, "executionId": "example-C-assertion-drift", "project": "fixture/C-assertion-drift", "createdAt": "2026-10-24T18:29:57.610Z", "baselineRevision": "shop-v1", "candidateRevision": "C-assertion-drift", "database": { "serverVersion": "16.15 (Debian 16.15-1.pgdg12+2)" }, "proposedMigrations": [ "002_status_default.sql" ], "experiment": [ "control: old application (shop-v1) × baseline schema (1 migrations)", "candidate ×2: old application (shop-v1) × proposed schema (2 migrations)" ], "verdict": "ADVISORY", "blocking": false, "exitCode": 0, "summary": "Something changed for the previous application version, but the evidence is not sufficient to call it a compatibility regression.", "reasons": [ "test/orders.test.js: assertion drift" ], "recommendedAction": "Review the listed findings and decide whether the old version's changed behaviour is acceptable during rollout.", "complete": true, "findings": [ { "kind": "assertion_drift", "test": "test/orders.test.js", "facts": [ "test/orders.test.js passes on the baseline schema and fails in all candidate runs without any new database error.", "Test output (tail): error: |- | Expected values to be strictly equal: | code: 'ERR_ASSERTION' | name: 'AssertionError'" ], "interpretation": "Likely a changed value or behaviour rather than a schema incompatibility (behavioural changes in this migration: Column orders.status default 'new'::text → 'pending'::text). A human should decide whether the old application's expectation still matters while both versions run.", "changeIds": [ "column_default_changed:orders.status" ] } ], "schemaChanges": [ { "id": "column_default_changed:orders.status", "kind": "column_default_changed", "risk": "behavioral", "schema": "public", "table": "orders", "column": "status", "before": "'new'::text", "after": "'pending'::text", "exercisedBy": [ "insert" ], "note": "Inserts that omit this column will store a different value." } ], "coverage": [ { "changeId": "column_default_changed:orders.status", "target": "orders.status", "risk": "behavioral", "required": true, "exercised": true, "statementCount": 2, "tests": [ "test/orders.test.js" ], "staticReferences": [ "src/orders.js:5", "src/orders.js:12", "src/orders.js:16", "test/orders.test.js:9", "test/orders.test.js:12" ] } ], "coverageSummary": "1 of 1 risk-bearing schema change(s) were exercised by the old application's tests in the control run.", "runs": [ { "id": "ctl", "label": "control (old app × baseline schema)", "app": "baseline", "schema": "baseline", "database": "sc_ctl", "revision": "shop-v1", "completed": true, "migrations": [ { "file": "001_init.sql", "ok": true } ], "tests": [ { "test": "test/customers.test.js", "outcome": "pass", "exitCode": 0, "durationMs": 103, "outputTail": "TAP version 13\n# Subtest: signs up a customer and finds them by email\nok 1 - signs up a customer and finds them by email\n ---\n duration_ms: 10.508789\n ...\n1..1\n# tests 1\n# suites 0\n# pass 1\n# fail 0\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 73.861289\n" }, { "test": "test/orders.test.js", "outcome": "pass", "exitCode": 0, "durationMs": 102, "outputTail": "TAP version 13\n# Subtest: new orders start in status \"new\" and can be shipped\nok 1 - new orders start in status \"new\" and can be shipped\n ---\n duration_ms: 13.362002\n ...\n1..1\n# tests 1\n# suites 0\n# pass 1\n# fail 0\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 75.922529\n" } ], "errors": [], "statements": 7 }, { "id": "cand1", "label": "candidate #1 (old app × proposed schema)", "app": "baseline", "schema": "candidate", "database": "sc_cand1", "revision": "shop-v1", "completed": true, "migrations": [ { "file": "001_init.sql", "ok": true }, { "file": "002_status_default.sql", "ok": true } ], "tests": [ { "test": "test/customers.test.js", "outcome": "pass", "exitCode": 0, "durationMs": 100, "outputTail": "TAP version 13\n# Subtest: signs up a customer and finds them by email\nok 1 - signs up a customer and finds them by email\n ---\n duration_ms: 10.663535\n ...\n1..1\n# tests 1\n# suites 0\n# pass 1\n# fail 0\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 71.590066\n" }, { "test": "test/orders.test.js", "outcome": "fail", "exitCode": 1, "durationMs": 100, "outputTail": "TAP version 13\n# Subtest: new orders start in status \"new\" and can be shipped\nnot ok 1 - new orders start in status \"new\" and can be shipped\n ---\n duration_ms: 11.398998\n location: '/test/orders.test.js:9:1'\n failureType: 'testCodeFailure'\n error: |-\n Expected values to be strictly equal:\n \n 'pending' !== 'new'\n \n code: 'ERR_ASSERTION'\n name: 'AssertionError'\n expected: 'new'\n actual: 'pending'\n operator: 'strictEqual'\n stack: |-\n TestContext. (/test/orders.test.js:12:10)\n process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n async Test.run (node:internal/test_runner/test:935:9)\n async startSubtestAfterBootstrap (node:internal/test_runner/harness:296:3)\n ...\n1..1\n# tests 1\n# suites 0\n# pass 0\n# fail 1\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 72.532381\n" } ], "errors": [], "statements": 4 }, { "id": "cand2", "label": "candidate #2 (old app × proposed schema)", "app": "baseline", "schema": "candidate", "database": "sc_cand2", "revision": "shop-v1", "completed": true, "migrations": [ { "file": "001_init.sql", "ok": true }, { "file": "002_status_default.sql", "ok": true } ], "tests": [ { "test": "test/customers.test.js", "outcome": "pass", "exitCode": 0, "durationMs": 97, "outputTail": "TAP version 13\n# Subtest: signs up a customer and finds them by email\nok 1 - signs up a customer and finds them by email\n ---\n duration_ms: 10.17595\n ...\n1..1\n# tests 1\n# suites 0\n# pass 1\n# fail 0\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 70.002439\n" }, { "test": "test/orders.test.js", "outcome": "fail", "exitCode": 1, "durationMs": 99, "outputTail": "TAP version 13\n# Subtest: new orders start in status \"new\" and can be shipped\nnot ok 1 - new orders start in status \"new\" and can be shipped\n ---\n duration_ms: 11.811819\n location: '/test/orders.test.js:9:1'\n failureType: 'testCodeFailure'\n error: |-\n Expected values to be strictly equal:\n \n 'pending' !== 'new'\n \n code: 'ERR_ASSERTION'\n name: 'AssertionError'\n expected: 'new'\n actual: 'pending'\n operator: 'strictEqual'\n stack: |-\n TestContext. (/test/orders.test.js:12:10)\n process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n async Test.run (node:internal/test_runner/test:935:9)\n async startSubtestAfterBootstrap (node:internal/test_runner/harness:296:3)\n ...\n1..1\n# tests 1\n# suites 0\n# pass 0\n# fail 1\n# cancelled 0\n# skipped 0\n# todo 0\n# duration_ms 72.564437\n" } ], "errors": [], "statements": 4 } ], "skippedChecks": [ "Current application × proposed schema (no current app configured).", "Performance / lock-time analysis (out of scope)." ], "limitations": [ "Skewcheck only observes code paths that the old application's tests execute; untested paths are reported as coverage gaps, not as safe.", "Coverage is identifier-level: a statement \"touches\" a changed object when it names the table (and column, or uses *). It is not a SQL parser.", "Correlation between an error and a schema change uses a fixed set of deterministic rules (R1–R6). Anything else is reported as ADVISORY, never UNSAFE.", "Performance, locking and migration runtime on production-sized data are not evaluated.", "Test files of one run share a database and run sequentially; ordering effects are identical across runs but are not isolated.", "Data-only migration effects are detected only when a test asserts on the affected data." ], "policy": { "advisory": "warn", "noEvidence": "block", "inconclusive": "block", "candidateRepeats": 2, "testTimeoutMs": 60000, "maxBaselineFailureRatio": 0.5, "protectedPaths": [], "repairBranchPrefixes": [ "skewcheck-repair/" ] } }