Activeonly (#7)

* add ActiveOnly ret test to CI

* cleanup

samples/tests/reverse/mod.rs

@@ -1,6 +1,6 @@
 samples::test! {
     square;
-    /// ANCHOR: square
+    // ANCHOR: square
     #[autodiff(d_square, Reverse, Duplicated, Active)]
     fn square(x: &f64) -> f64 {
         x * x
@@ -19,8 +19,29 @@ samples::test! {
     // ANCHOR_END: square
 }
 
+samples::test! {
+    active_only;
+    // ANCHOR:  active_only
+    #[autodiff(d_f, Reverse, Active, Active)]
+    #[autodiff(d_f2, Reverse, Active, ActiveOnly)]
+    fn f(x: f64) -> f64 {
+        f64::sin(x)
+    }
+
+    fn main() {
+        let x = 1.0;
+        let (_y, d_y) = d_f(x, 1.0);
+        let d2_y = d_f2(x, 1.0);
+        let cos_x = f64::cos(x);
+        assert!((d2_y - d_y).abs() < 1e-15);
+        assert!((cos_x - d_y).abs() < 1e-15);
+    }
+    // ANCHOR_END: active_only
+}
+
 samples::test! {
     self_duplicated;
+    // ANCHOR: self_duplicated
     struct Ogden {
         k: f64,
     }
@@ -39,6 +60,7 @@ samples::test! {
         let res = 2.0 * vol.k;
         assert!((out.k - res).abs() < 1e-15, "{} {}", res, out.k);
     }
+    // ANCHOR_END: self_duplicated
 }
 
 samples::test! {