"runtime/metrics"
	"testing"
)

func TestPanicNil(t *testing.T) {
	t.Run("default", func(t *testing.T) {
		checkPanicNil(t, new(runtime.PanicNilError))
	})
	t.Run("GODEBUG=panicnil=0", func(t *testing.T) {
		t.Setenv("GODEBUG", "panicnil=0")
		checkPanicNil(t, new(runtime.PanicNilError))
	})
	t.Run("GODEBUG=panicnil=1", func(t *testing.T) {
		t.Setenv("GODEBUG", "panicnil=1")
		checkPanicNil(t, nil)
	})
}

	calls := 0
	f := sync.OnceFunc(func() {
		calls++
		panic(nil)
	})
	testOncePanicWith(t, &calls, f, func(label string, p any) {
		switch p.(type) {
		case nil, *runtime.PanicNilError:
			return
		}
		t.Fatalf("%s: want nil panic, got %v", label, p)
	})
}

func TestOnceFuncGoexit(t *testing.T) {
	// If f calls Goexit, the results are unspecified. But check that f doesn't