Add same test as stub to generator

generator/function_test.go

@@ -105,6 +105,22 @@ Number.[number]: Int = [.this]
 `)
 }
 
+func TestMethodChained (test *testing.T) {
+testString (test,
+`
+`,
+`
+Number: Int
+
+Number.[add x:Number]:Number = [+ [.this] x]
+Number.[sub x:Number]:Number = [- [.this] x]
+Number.[mul x:Number]:Number = [* [.this] x]
+Number.[div x:Number]:Number = [/ [.this] x]
+
+[main]: Number = [~Number 5].[add 8].[mul 3]
+`)
+}
+
 func TestMethodGreeter (test *testing.T) {
 testString (test,
 `%Index = type i64