Function TestEachKeyMultiPathInvariants

path_fuzz_test.go:786–827

TestEachKeyMultiPathInvariants closes the EachKey multi-path blind spot deterministically. EachKey's purpose is to resolve MULTIPLE key paths in one traversal; the existing fuzz harnesses test only single-path. This test verifies the multi-path callback contract: each path that matches fires the cal

(t *testing.T)

//
// Verifies: SYS-REQ-008 (EachKey multi-path traversal correctness).
func TestEachKeyMultiPathInvariants(t *testing.T) {
	data := []byte(`{"a":1,"b":2,"nested":{"x":10,"y":20},"arr":[100,200,300]}`)
	paths := [][]string{
		{"a"},
		{"b"},
		{"missing_top"},
		{"nested", "x"},
		{"nested", "missing_nested"},
		{"nested", "y"},
		{"arr", "[1]"},
	}
	matched := make(map[int]int) // idx → number of times callback fired
	callbackCount := 0
	EachKey(data, func(idx int, value []byte, vt ValueType, err error) {
		matched[idx]++
		callbackCount++
		// No-error invariant on matched paths.
		if err != nil {
			t.Errorf("EachKey callback for path %d returned error %v (data=%q)",
				idx, err, data)
		}
		if len(value) == 0 {
			t.Errorf("EachKey callback for path %d returned empty value (data=%q)",
				idx, data)
		}
	}, paths...)

	// Each matching path should fire at most once. (We can't assert "exactly
	// once" without knowing which paths matched, but we CAN assert no path
	// fires more than once — that would be a state-leakage bug.)
	for idx, count := range matched {
		if count > 1 {
			t.Errorf("EachKey path %d fired %d times (expected at most 1): data=%q paths=%v",
				idx, count, data, paths)
		}
	}
	// Sanity: at least the trivially-matching paths must have fired.
	if callbackCount == 0 {
		t.Errorf("EachKey multi-path: callback never fired despite some paths matching: data=%q paths=%v",
			data, paths)
	}
}