add of the test function for opwi instructions

src/print.rs

@@ -339,5 +339,15 @@ mod test {
         assert_eq!("sraw x28, x17, x16", print::print(sraw, 0));
     }
 
+    #[test]
+    fn test_opwi() {
+        let addwi: decode::Instruction =decode::decode(0b000000000000_10001_000_11100_0011011);
+        let sllwi: decode::Instruction = decode::decode(0b0000000_10000_10001_001_11100_0011011);
+        let srai: decode::Instruction = decode::decode(0b010000010001_10001_101_11100_0010011);
+        assert_eq!("addwi x28, x17, x0", print::print(addwi, 0));
+        assert_eq!("slli x28, x17, x16", print::print(sllwi, 0));
+        assert_eq!("srai x28, x17, 17", print::print(srai, 0));
+
+    }
 
 }