fx.ValidateApp fails on a valid graph when using fx.Decorate

[vladimir-gavrilenko]

Describe the bug
Functions inside fx.Decorate are invoked with nils as required parameters when calling fx.ValidateApp.

To Reproduce
If I take a snippet from the docs, and make a unit test, fx.ValidateApp will panic.

func TestDecoratorScope(t *testing.T) {
	opts := fx.Options(
		fx.Module("mymodule",
			fx.Decorate(func(log *zap.Logger) *zap.Logger {
				return log.Named("myapp")
			}),
			fx.Invoke(func(log *zap.Logger) {
				log.Info("decorated logger")
				// Output:
				// {"level": "info","logger":"myapp","msg":"decorated logger"}
			}),
		),
		fx.Invoke(func(log *zap.Logger) {
			log.Info("plain logger")
			// Output:
			// {"level": "info","msg":"plain logger"}
		}),
		fx.Provide(zap.NewProduction),
	)

	// uncomment the line below to panic
	// assert.NoError(t, fx.ValidateApp(opts))
	app := fxtest.New(t, opts)
	app.RequireStart().RequireStop()
}

Expected behavior
If an app can run, fx.ValidateApp should not cause a panic.

Additional context
n/a

[JacobOaks]

Thanks for reporting this. I've reproduced the panic and will look into it.

[sywhang]

This issue was fixed in Dig. If you update your dependency to the latest version of Dig (v1.16.1), that should address the issue.