Key:      k,
		Operator: metav1.LabelSelectorOpExists,
	}
	s.MatchExpressions = append(s.MatchExpressions, expression)
	return s
}

// NotExist injects a matchExpression (with an operator NotExist) to the inner labelSelector.
func (s *LabelSelectorWrapper) NotExist(k string) *LabelSelectorWrapper {
	expression := metav1.LabelSelectorRequirement{
		Key:      k,
		Operator: metav1.LabelSelectorOpDoesNotExist,
	}

	// but can be a state transition event from NotExist or Undetermined
	// if the region is a synthetic region representing task inheritance
	// from the parent goroutine.
	Start *Event

	// Region end event. Normally EventRegionEnd event or nil,
	// but can be a state transition event to NotExist if the goroutine
	// terminated without explicitly ending the region.
	End *Event

		const mainLine = 21
		want := []evDesc{
			{trace.EventStateTransition, "Goroutine Running->Runnable", []frame{
				{"main.main", mainLine + 82},
			}},
			{trace.EventStateTransition, "Goroutine NotExist->Runnable", []frame{
				{"main.main", mainLine + 11},
			}},
			{trace.EventStateTransition, "Goroutine Running->Waiting", []frame{
				{"runtime.block", 0},
				{"main.main.func1", 0},
			}},

	// along with a nil error if the list of matching versions
	// is known to be empty.
	//
	// If the underlying repository does not exist,
	// Versions returns an error matching errors.Is(_, os.NotExist).
	Versions(ctx context.Context, prefix string) (*Versions, error)

	// Stat returns information about the revision rev.
	// A revision can be any identifier known to the underlying service:

func TestEvalSymlinksIsNotExist(t *testing.T) {
	testenv.MustHaveSymlink(t)

	defer chtmpdir(t)()

	_, err := filepath.EvalSymlinks("notexist")
	if !os.IsNotExist(err) {
		t.Errorf("expected the file is not found, got %v\n", err)
	}

	err = os.Symlink("notexist", "link")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove("link")

	_, err = filepath.EvalSymlinks("link")