Function pickExistingPath

reference_oracle_test.go:270–300

--------------------------------------------------------------------------- Path picker — walks a random Go value tree to produce a path that EXISTS. Returns the path components and the Go value at that path. ---------------------------------------------------------------------------

(r *mathrand.Rand, v interface{})

// ---------------------------------------------------------------------------

func pickExistingPath(r *mathrand.Rand, v interface{}) ([]string, interface{}) {
	cur := v
	var path []string
	// Bound the walk so we don't infinite-loop on cyclic data (json.Marshal
	// rejects cycles anyway, so this is defensive only).
	for i := 0; i < 16; i++ {
		switch node := cur.(type) {
		case map[string]interface{}:
			if len(node) == 0 || r.Intn(3) == 0 {
				return path, cur
			}
			keys := make([]string, 0, len(node))
			for k := range node {
				keys = append(keys, k)
			}
			k := keys[r.Intn(len(keys))]
			path = append(path, k)
			cur = node[k]
		case []interface{}:
			if len(node) == 0 || r.Intn(3) == 0 {
				return path, cur
			}
			idx := r.Intn(len(node))
			path = append(path, fmt.Sprintf("[%d]", idx))
			cur = node[idx]
		default:
			return path, cur
		}
	}
	return path, cur
}

// pickAdversarialPath produces a path that may NOT exist in v, including
// out-of-range indices and empty components — exactly the inputs that