Add test for unit_struct

tests/test_serde.rs

@@ -164,7 +164,6 @@ fn test_float32() {
     "})
     .unwrap();
     assert!(single_float.is_nan());
-
 }
 
 #[test]
@@ -273,6 +272,18 @@ fn test_unit() {
     test_serde(&thing, yaml);
 }
 
+#[test]
+fn test_unit_struct() {
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    struct Foo;
+    let thing = Foo;
+    let yaml = indoc! {"
+        ---
+        ~
+    "};
+    test_serde(&thing, yaml);
+}
+
 #[test]
 fn test_unit_variant() {
     #[derive(Serialize, Deserialize, PartialEq, Debug)]