Function roundtrip

packages/effect/test/schema/toDifferJsonPatch.test.ts:19–47

* This suite intentionally avoids re-testing generic JSON Patch behavior * (pointer parsing, add/replace/remove mechanics, ordering, etc). * * It focuses on Schema.toDifferJsonPatch-specific guarantees: * - reference preservation when patch is a no-op * - reference replacement for root replace

(codec: Schema.Codec<T, E>)

 */

function roundtrip<T, E>(codec: Schema.Codec<T, E>) {
  const differ = Schema.toDifferJsonPatch(codec)
  const arbitrary = Schema.toArbitrary(codec)(FastCheck)
  const arb = arbitrary.filter((v) => {
    // avoid prototype-poisoning-ish values that aren't valid JSON-ish containers for patching
    if (
      typeof v === "object" &&
      v !== null &&
      (Object.getPrototypeOf(v) === null || Object.hasOwn(v as any, "__proto__"))
    ) {
      return false
    }
    return true
  })

  FastCheck.assert(
    FastCheck.property(arb, arb, (v1, v2) => {
      const patch = differ.diff(v1, v2)
      const patched = differ.patch(v1, patch)

      // two invalid dates are not considered equal by deepStrictEqual
      if (patched instanceof Date && v2 instanceof Date && Object.is(patched.getTime(), v2.getTime())) {
        return
      }

      deepStrictEqual(patched, v2)
    })
  )
}

describe("Schema.toDifferJsonPatch", () => {
  describe("structural guarantees", () => {