Function runStreamingConsistencyGate

encoding_json_fuzz_test.go:348–396

============================================================================= Gate E: Streaming Decoder vs one-shot Unmarshal consistency ============================================================================= runStreamingConsistencyGate asserts that json.NewDecoder.Decode and json.Unmarshal a

(t *testing.T, data []byte)

// historically; this gate surfaces any divergence not explained by the
// trailing-data semantic.
func runStreamingConsistencyGate(t *testing.T, data []byte) {
	t.Helper()

	var decV interface{}
	var decErr error
	encodingJSONNoPanic(t, "Streaming/Decode", data, func() {
		dec := json.NewDecoder(bytes.NewReader(data))
		decErr = dec.Decode(&decV)
	})

	var unV interface{}
	var unErr error
	encodingJSONNoPanic(t, "Streaming/Unmarshal", data, func() {
		unErr = json.Unmarshal(data, &unV)
	})

	valid := json.Valid(data)

	if decErr == nil && unErr == nil {
		// Both succeeded: values must match.
		if !reflect.DeepEqual(decV, unV) {
			t.Errorf("Gate E: Decoder and Unmarshal both succeeded but values differ:\n"+
				"  decoder=%#v\n  unmarshal=%#v\n  data=%s",
				decV, unV, truncateForMsg(data))
		}
		return
	}
	if decErr != nil && unErr != nil {
		// Both failed: they agree. For valid JSON this is the documented
		// float64-range limitation (e.g. 1e999 overflows float64 identically
		// under both the streaming and one-shot paths); for invalid JSON it
		// is expected. Either way, Decoder and Unmarshal agree.
		return
	}
	// Exactly one succeeded while the other failed.
	if valid {
		// For VALID JSON there is no trailing-data semantic to explain the
		// divergence — this is a genuine streaming-vs-one-shot inconsistency.
		t.Errorf("Gate E: on valid JSON, Decoder and Unmarshal disagree on success "+
			"(decErr=%v, unErr=%v): data=%s",
			decErr, unErr, truncateForMsg(data))
		return
	}
	// For INVALID JSON: the only documented reason for exactly one of the two
	// to succeed is the streaming Decoder's trailing-data semantic — it reads
	// ONE top-level value and ignores the rest, while Unmarshal rejects
	// trailing bytes (so "{}{}" decodes the first "{}" but fails to unmarshal).
	// This is the KNOWN, legitimate divergence and is NOT flagged.
}

// =============================================================================
// Gate F: Compact / Indent / HTMLEscape must never panic