Add test for zero input in randNum

This commit introduces a new test case in random_test.go to ensure that the randNum function returns zero when given an input of zero. This helps validate the correctness of edge case handling in the random number generation logic.

random_test.go

@@ -62,3 +62,10 @@ func TestRandomNum(t *testing.T) {
 		})
 	}
 }
+
+func TestRandomNumZero(t *testing.T) {
+	rn := randNum(0)
+	if rn != 0 {
+		t.Errorf("random number generation failed: %d is not zero", rn)
+	}
+}