Function injectMismatchedCloser

json_fuzz_test.go:911–925

injectMismatchedCloser swaps a closing '}' for ']' (or vice versa). The grammar generator always pairs '{' with '}' and '[' with ']'; this operator produces the cross-type mismatch class ([{...}] → [{...]}) that stresses blockEnd's open/close pairing logic.

(r *rand.Rand, data []byte)

// operator produces the cross-type mismatch class ([{...}] → [{...]}) that
// stresses blockEnd's open/close pairing logic.
func injectMismatchedCloser(r *rand.Rand, data []byte) []byte {
	closers := findStructuralBytes(data, '}', ']')
	if len(closers) == 0 {
		return data
	}
	idx := closers[r.Intn(len(closers))]
	out := make([]byte, len(data))
	copy(out, data)
	if out[idx] == '}' {
		out[idx] = ']'
	} else {
		out[idx] = '}'
	}
	return out
}

// =============================================================================
// Adversarial key-path generator