--- title: No Newman PASS, No Output: How I Made My API Drift... description: API Drift Healer V1.2 adds runtime validation to its Postman collection repair workflow. Previously, the tool could detect when a Postman request used an... canonical: https://daily.dev/posts/no-newman-pass-no-output-how-i-made-my-api-drift-healer-safer-zsqs0qs5q twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: No Newman PASS, No Output: How I Made My API Drift Healer Safer | daily.dev og:description: API Drift Healer V1.2 adds runtime validation to its Postman collection repair workflow. Previously, the tool could detect when a Postman request used an... og:url: https://daily.dev/posts/no-newman-pass-no-output-how-i-made-my-api-drift-healer-safer-zsqs0qs5q og:image: https://api.daily.dev/og/posts/zsQS0qs5Q.png og:image:alt: No Newman PASS, No Output: How I Made My API Drift Healer Safer og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # No Newman PASS, No Output: How I Made My API Drift Healer Safer **[ITNEXT](https://daily.dev/sources/itnext)** · 7 min read · 0 upvotes · 0 comments ## Summary API Drift Healer V1.2 adds runtime validation to its Postman collection repair workflow. Previously, the tool could detect when a Postman request used an outdated field name compared to an OpenAPI contract and generate a corrected JSON file — but valid JSON alone doesn't prove the fix works. V1.2 integrates Newman (Postman's CLI runner) to actually execute both the original and healed collections: the original must fail, the healed version must pass, and only then is the validated output written. The update also adds cross-platform support (including Windows newman.cmd handling and UTF-8 subprocess output), Postman environment file support, configurable timeouts, and a Flask-based demo. The patch decision remains deterministic code, not LLM-driven, with Newman providing runtime proof. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How can I verify that an automatically generated Postman collection patch actually fixes a failing API test, not just produce valid JSON? Run the original collection with Newman and confirm it fails, then run the patched collection and confirm it passes; only write the final validated output when both conditions hold. This is the approach used in API Drift Healer v1.2, which also skips writing output entirely if the original collection unexpectedly already passes, unless overridden with an --allow-original-pass flag. _daily.dev surfaces practical patterns like this for teams automating API contract drift detection._ ### Why does Newman crash when reading its terminal output on Windows even though the test run itself passed? Newman prints box-drawing characters in its report, and Python's default Windows encoding fails to decode them, causing the automated test wrapper to crash after the actual Newman run succeeded. The fix is to capture the subprocess output explicitly as UTF-8 with errors="replace" when calling subprocess.run, rather than relying on the platform default encoding. _developers hardening cross-platform CLI tooling can track fixes like this via daily.dev._ ## Similar posts on daily.dev - [Auto-Healing Postman Tests from OpenAPI Drift](https://daily.dev/posts/auto-healing-postman-tests-from-openapi-drift-c0ialt53t) · ITNEXT · 0 upvotes · 0 comments - [Building a Safer API Drift Healer: Deterministic Field Matching in V0.4](https://daily.dev/posts/building-a-safer-api-drift-healer-deterministic-field-matching-in-v0-4-pik20hji6) · ITNEXT · 0 upvotes · 0 comments - [Postman Adds Open Source Documentation and SDK Products](https://daily.dev/posts/postman-adds-open-source-documentation-and-sdk-products-wwndgjmjk) · The New Stack · 0 upvotes · 0 comments --- Tags: [#python](https://daily.dev/tags/python), [#testing](https://daily.dev/tags/testing), [#openapi](https://daily.dev/tags/openapi), [#postman](https://daily.dev/tags/postman) [View this post on daily.dev](https://daily.dev/posts/no-newman-pass-no-output-how-i-made-my-api-drift-healer-safer-zsqs0qs5q) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"No Newman PASS, No Output: How I Made My API Drift Healer Safer","url":"https://daily.dev/posts/no-newman-pass-no-output-how-i-made-my-api-drift-healer-safer-zsqs0qs5q","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/no-newman-pass-no-output-how-i-made-my-api-drift-healer-safer-zsqs0qs5q"},"datePublished":"2026-07-27T20:07:31.397Z","dateModified":"2026-09-13T18:29:09.968Z","description":"API Drift Healer V1.2 adds runtime validation to its Postman collection repair workflow. 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