Add roundtrip example test case.

src/de.rs

@@ -730,11 +730,11 @@ where
             0xf8 => Err(self.error(ErrorCode::UnassignedCode)),
             0xf9 => {
                 let value = self.parse_f16()?;
-                visitor.visit_f32(value)
+                visitor.visit_f64(value as f64)
             }
             0xfa => {
                 let value = self.parse_f32()?;
-                visitor.visit_f32(value)
+                visitor.visit_f64(value as f64)
             }
             0xfb => {
                 let value = self.parse_f64()?;

tests/roundtrip.rs

@@ -0,0 +1,31 @@
+#[macro_use]
+extern crate serde_derive;
+
+#[cfg(feature = "std")]
+mod roundtrip {
+
+    use serde_cbor;
+
+    #[derive(Serialize, Deserialize, Debug, PartialEq)]
+    struct MyStuff {
+        #[serde(flatten)]
+        data: MyStuffType,
+    }
+
+    #[derive(Serialize, Deserialize, Debug, PartialEq)]
+    enum MyStuffType {
+        Ver1 { x: f64, y: f32 },
+        Ver2,
+    }
+
+    #[test]
+    /// Test roundtrip operation on a serde data structure.
+    fn test_roundtrip() {
+        let stuff1 = MyStuff {
+            data: MyStuffType::Ver1 { x: 2.5, y: 2.5 },
+        };
+        let data_bytes = serde_cbor::to_vec(&stuff1).unwrap();
+        let stuff2 = serde_cbor::from_slice(&data_bytes).unwrap();
+        assert_eq!(stuff1, stuff2);
+    }
+}