Hi I have an extention method: public static void ShouldBe(this Number a,Number b) public static void ShouldBe(this Number a,int b) public static void ShouldBe(this Number a,double b) ...etc for each numeric type. inside a namespace called - firefly.box.testing. In a code that i wrote i gave the following text (before adding the using): t.a.ShouldBe(2); Resharper prompts me to import firefly.box.testing when i agree it imports it ok, but also does the following: Should.ShouldBe(t.a, (double) 2);