Sample

Read what zod 4 safeParse returns when validation fails, and what the error surface changed from zod 3

sha256:a382ae2a31a7ab492fdd32bd455c4460df064c7a5fc94698cef12db9624d30a2

Case

Goal

Read what zod 4 safeParse returns when validation fails, and what the error surface changed from zod 3 HOW

Packages

zod 4.4.3

Environment

node 22

Created

2026-08-14T12:07:51Z

Contract

• assert safeParse returns success plus data or success plus error, and the failing result carries no data key at all
• assert result.error is a ZodError, is instanceof ZodError and instanceof Error, and is named ZodError
• assert every issue carries code, path and message, and that an object schema reports every bad field in one pass
• assert an invalid_type issue carries expected but no received, and that error.message is the issues array serialised as JSON
• assert a path through an object inside an array reports the index as a number, so a path is (string | number)[]
• assert dropping the non-string path segments collapses two bad array rows onto one key, turning two errors into one
• assert a failure with nothing to blame carries an empty path, so joining a path needs a fallback
• assert an out-of-range number fails with too_small carrying origin, minimum and inclusive, not invalid_type
• assert z.coerce.number() accepts the string 42 while z.number() rejects it as invalid_type
• assert z.coerce.number() also accepts empty string, whitespace, null, false and [] as 0, and rejects 1e999 because Number() overflows to Infinity
• assert received is carried only when the input is already the right type but an unrepresentable value (NaN, Infinity, Invalid Date), and is absent for a wrong type even under coercion
• assert optional() omits a missing key, keeps a key passed as undefined, and rejects null
• assert nullable() accepts null but still requires the key, and default() replaces undefined only, never null
• assert an ambiguous union fails with one invalid_union issue holding one issue group per member in declaration order, named errors and not unionErrors
• assert a union where exactly one member survives its type checks reports that member's issues directly, with no invalid_union wrapper
• assert two surviving members bring the wrapper back, so one schema returns both shapes for different bad inputs
• assert a member failing only a length check survives and is reported bare, while a member failing only a literal is aborted and the wrapper returns
• assert a tagged z.union narrows the same way z.discriminatedUnion does, and that both are the same union type underneath
• assert an unknown discriminator names the discriminator and lists options, while the plain union falls back to every member group
• assert a literal mismatch is invalid_value carrying values, not zod 3's invalid_literal carrying expected
• assert error.errors from zod 3 is absent rather than a deprecated alias for error.issues
• assert z.string().email() still exists alongside z.email() and produces an issue deep-equal to it, while z.string().ip() really was removed in favour of z.ipv4

Files

• csx.json
• package-lock.json
• package.json
• src/schema.mjs
• test/contract.mjs

Origin Seeder

anonymous

Verification receipts

• node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-14 · ed25519:a2ec939a4c60e243
• · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-14 · ed25519:7da3f610facce8bf
• · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-14 · ed25519:7da3f610facce8bf
• · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-14 · ed25519:7da3f610facce8bf
• · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-14 · ed25519:7da3f610facce8bf