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TODO: fix error in json / schema / json #40

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Merged
lazamar merged 3 commits into from
Feb 6, 2026
Merged

TODO: fix error in json / schema / json #40

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45409e3
TODO: fix error in json / schema / json
EthanRBrown Feb 4, 2026
177906a
Use explicit __proto__ test
lazamar Feb 6, 2026
d70c1a1
Fix decoding of objects with protected keys
lazamar Feb 6, 2026
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3 changes: 2 additions & 1 deletion core/src/json/decoder.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -210,7 +210,8 @@ const objectMap = <A>(decoder: Decoder<A>): Decoder<ObjectMap<A>> =>
return failure('expected object but found ' + typeof input);
}

const result = {} as ObjectMap<A>;
// object without a prototype or built-in functions.
const result = Object.create(null) as ObjectMap<A>;
for (const field in input) {
// @ts-ignore
const decoded = decoder.run(input[field]);
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19 changes: 15 additions & 4 deletions core/tests/suites/json.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,7 @@ const tests = group('json', [
)),
test('pair', () =>
roundtrip(s.pair(s.string, s.number), ['wat', 2] as [string, number])),
test('tripple', () =>
test('triple', () =>
roundtrip(s.triple(s.string, s.number, s.boolean), ['wat', 2, false] as [
string,
number,
Expand All @@ -72,7 +72,11 @@ const tests = group('json', [
.dictionary(genString(), fc.boolean())
.map((v) => new Map(Object.entries(v)))
)),
test('json', () => roundtripTest(s.json, genJson())),
group('json', [
test('plain', () => roundtripTest(s.json, genJson())),
test('with "__proto__" key', () =>
roundtrip(s.json, [{ ['__proto__']: [] }])),
]),
group('recursive', [
test('base case', () => {
type List =
Expand Down Expand Up @@ -553,10 +557,17 @@ function genJson(lvl = 0): fc.Arbitrary<Json> {
);
}

function roundtripTest<T>(schema: Schema<T>, gen: fc.Arbitrary<T>): void {
function roundtripTest<T>(
schema: Schema<T>,
gen: fc.Arbitrary<T>,
assertOptions?: fc.Parameters<[v: T]>
): void {
fc.assert(
fc.property(gen, (v) => roundtrip(schema, v)),
{ includeErrorInReport: true }
{
includeErrorInReport: true,
...assertOptions,
}
);
}

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